Historically, everything from autogenous bone to xenografts, allografts, and alloplastic materials has been used and studied in dentistry when a graft or graft substitute is needed. These different materials have all been used with great success over the years, and they continue to provide clinically successful results. The alloplastic class over the years has become an exciting class since it is continually being advanced at a greater rate by new products than the allograft and xenograft classes.

Everyday, practitioners are faced with the need to graft and regenerate new bone. This can be an extraction site, an existing defect, or in combination procedures such as immediate implant placements or sinus elevations. The purpose of a graft material is to not only maintain clinical bone volume but also also to provide a framework for new bone growth as the particles are resorbed for new bone regeneration. Only in the case of an autograft will osteogenesis occur, as there are live cells capable of proliferating to create new bone. Therefore, a bone substitute is a natural or synthetic material, often containing only a mineralized bone matrix with no viable cells.¹ 

In studies, the 3 main classes of graft materials (allograft, xenograft, and alloplast) all showed the presence of newly formed bone with residual graft particles and connective tissue in greater or lesser amounts. The presence of newly formed bone in direct contact with residual particles of each bone substitute material indicated the adequate osteoconductive capacity.² 

This article will compare the makeup and advantages/disadvantages of the materials noted above and then focus on a material consisting of non-ceramic, synthetic, bioactive resorbable calcium apatite crystals known as OsteoGen (IMPLADENT LTD). These hydrophilic cluster particulates have physicochemical and crystallographic properties similar to human minerals. The low-temperature, bioactive calcium phosphate mineral also has the ability to control the migration of connective tissue.³ 

We are now going to look at and compare individual classes of graft materials to better understand the advantages of OsteoGen.

AUTOGENOUS BONE

Autografts remain the gold standard for grafting materials as they are still the only graft material that possesses the 4 fundamental biological properties required for bone regeneration, but they are not without issues.^1,4

An advantage of the use of autogenous bone graft materials is that they represent the highest degree of biological safety, and there are no histocompatibility or immunogenicity issues associated with their use.

Even with autogenous bone grafts being considered the optimal choice for augmentation, the procedure usually requires harvesting bone from a distant donor site. This resulting second site morbidity can, has, and will continue to lead to patient dissatisfaction. 

ALLOGRAFTS

Allograft materials, which are derived from cadaveric sources, have been used for decades with great success. These materials come in many forms, including mineralized and demineralized particulates and puttys. They are also available in cortical and cancellous formulations or a blend of the 2.

On their own, cancellous autografts and allografts have poor mechanical strength in addition to exhibiting inadequate healing capacity. The tissue-processing techniques, including treatment with alcohol, acetic acid, or nitric acid, reduce the materials’ osteoinductive capabilities.^1,5 These graft materials can also cause local host inflammatory responses, which can result in fibrous tissue formation rather than healthy bone. This is of concern and can produce up to 62% connective tissue, which is not conducive to good implant support after load (Figure 1).

Figure 1. Four clinical studies of allografts (mineralized or demineralized) conducted at New York University College of Dentistry and the University of Texas San Antonio from 2002 to 2012.

Cortical particles, on the other hand, do provide structural support and provide a mineral storehouse, but these take longer to resorb. This increased resorption time is a distinct advantage when trying to either rebuild height/width or maintain osseous architecture when thin cortical plates are present after an extraction. 

The downside, a common issue with all types of particulate grafts, is the possibility of migration or loss of material. Even if the particles are bound, as in bone putty by a binder, the addition of fluids, including blood, can wash these products out during clinical delivery. Finally, the literature supports the possibility of disease transmission by this class of products.⁶ 

Caution: Not all mineralized graft materials are the same.

ALLOPLASTS 

Historically, many substances have been used as components for grafting in dentistry, either by themselves or as a binder with other graft materials. This author has used many of these with varying results. Calcium phosphate is one substance that has been used as a bone cement either to deliver antibiotics locally or to bind allograft or xenograft particulates. One example of this type of product is Fusion Bone Binder (Park Compounding Pharmacy). Bi-phasic calcium phosphate products such as Augma Biomaterials’ 3D Bond (Augma Biomaterials) and Bond Apetite are products that are used alone as a graft material. Beta-tricalcium phosphate (β-TCP) products such as Cerasorb M (Curesan) is another material used alone to graft sockets or defects around implants. 

DENSE SINTERED ALLOPLASTS AND XENOGRAFTS

The Food and Drug Administration refers to dense, non-resorbing products as bone filler and augmentation materials (BFAM), and these have been used extensively for many years. To overcome potential immunogenicity and morbidity at donor sites, artificial synthetic bone substitutes and natural materials are manufactured to closely mimic the biological properties of natural bone.¹ These alloplast materials are either derived from natural substances (ie, coralline) or man-made and can be a homogenous product or a mix of materials. A variety of synthetically and organically derived dense bone formulations have been used in dentistry and medicine. In dentistry, they are used for the therapeutic repair and restoration of osseous ridge defect sites, post-tooth extraction (including periodontal reconstruction), sinus augmentation with and without implants, and post cyst removal with questionable results. Since these products have weak regenerative abilities on their own, highly sintered alloplastic and organic bone substitutes are often augmented with growth factors and membranes at an increased cost to the practitioner.

When evaluating the rates of resorption of ceramic hydroxyapatite (HA) alloplastic materials, the results are questionable. Densely sintered at high temperatures, pure ceramic HA has low microporosity and high density and is prepared in relatively large particle size with long resorption times. Essentially, these materials closely resemble ceramics. Sintered (non-resorbable) HA materials,⁷ xenografts, and allografts are often subject to fibrous tissue encapsulation rather than becoming a viable part of the host bone.⁸ 

Upon tooth extraction, the goal is complete regeneration while preventing pathology from arising that could signal the patient’s immune response against getting involved, depending upon the type of graft material used. One consequence is the involvement of macrophage cells. In extraction sites where dense products such as ceramic HA, TCP, glass, polymers, coralline, and xenografts are placed, these macrophages are recruited. This is in contrast to the normal mechanism of osteoclastic breakdown. 

These cells are signaled by an immune response to remove the graft material as foreign matter, and these 18-µm cells will continue to enter the socket area through the nutrient canals in the lamina dura (Figure 2).

Figure 2. The tooth-alveolous construct.

This immune response is inevitable in the use of these products, and the immune system’s mechanism is to eventually produce multi-nucleated giant cells to fragment (not phagocytose) these dense graft materials and transport the residual pieces to larger filters in the body (ie, lymph nodes, lungs, and the spleen), resulting in the patient’s compromised immune system.^9,10

Studies have shown that highly dense bovine xenografts have also been shown to induce the formation of giant cells relatively early in the healing process.¹¹ 

Compared with allogeneic and xenogenic bone grafts, common advantages of non-resorbable alloplastic bone substitutes are the standardized product quality and absence of infectious disease risk. The main advantages of alloplastic non-resorbing bone substitutes involve their biological stability and volume maintenance, which allow cell infiltration and remodeling.¹² Originally HA ceramic and β-TCP products comprised 80% of all alloplastic bone graft products in the market. 

Xenografts can be derived from sources including bovine and porcine origins, with bovine being the most prominent graft source in the industry. Xenografts carry with them the potential for immunologic reaction resulting in the patient mounting a host immune response against the grafting material. The long-term clinical use and safety of xenografts and their potential association with severe immune responses, as well as objections to their use for both religious and ethical reasons, are valid concerns.

Dental literature has rarely addressed the clinical risks and complications of anorganic bovine bone as a grafting material. However, the scarce literature on complications does not mean that such events are unusual. Often, the negative findings are not published or are not being submitted for publication in dentistry; ignoring the negative outcomes is worrisome as it skews the scientific literature. To the authors, a major concern was the late complications caused by product not resorbing, extending from 2 to 13 years after what was considered to be a successful treatment outcome. In the study, adverse effects presented in the case series report included sinus and maxillary bone pathoses, displacement of the graft materials, oroantral communications, implant failure, foreign body reactions, encapsulation, chronic inflammation, soft-tissue fenestrations, and associated cysts.¹³

Finally, the amount of time it takes for full “resorption” of the bovine xenograft material is a potential issue due to the fragmentation of the particulate by multi-nucleated giant cells, which is of immunologic concern. Human biopsies after sinus augmentation confirm that particles of bovine-derived bone substitutes can still be found up to 10 years postoperatively.¹⁴

RESORBABLE CALCIUM APATITE CRYSTALS AND CLUSTERS

OsteoGen has been used as a particulate graft material since 1984 and has documented clinical success for use with implants, general osseous repair,¹⁵ periodontal procedures,¹⁶ and sinus lifts.¹⁷ When first developed and brought to market, OsteoGen crystals and clusters were used either alone or mixed with other graft materials to extend the amount of graft and to enhance new bone growth. Over the years, product development to address the needs of practitioners has driven new products that contain the OsteoGen crystals mixed with highly purified Achilles tendon collagen. These products include OsteoGen Plugs, OsteoGen Strips, OsteoGen Blocks, and OsteoGen Plates (Figure 3).

Figure 3. Available OsteoGen (IMPLADENT LTD) products.

The bioactive crystal is grown utilizing a unique low-temperature production process that generates osteoconductive and resorbable low-density crystals and crystal clusters (Figure 4). It has a unique calcium-to-phosphate ratio similar to human bone that is neither a β-TCP nor a dense, non-resorbable ceramic HA. 

Figure 4. Scanning electron micrograph of the OsteoGen crystal.

Figure 5. A 3-month histology by Dr. Kyle Hale at the University of Texas Health and Science Center.

As discussed previously, a non-autogenous bone graft material should ideally be non-antigenic, bioactive to control migration of connective tissue, osteoconductive, and synthetically derived with a clinically acceptable time frame of resorption of the majority of such material (Figure 5). The material does have physicochemical and crystallographic properties relatively similar to the host bone (Figure 6) and possesses a bioactive resorptive chemical potentiality to induce favorable cellular response for new bone formation by the action of ionization into calcium and phosphate ions in a chemotactic state.³ What this means is that the breakdown of the clusters produces the optimal environment on a cellular level for bone regeneration. 

Figure 6. A fractured cross section of OsteoGen bioactive crystal with similarity to natural bone.

The clusters are a highly microporous, non-sintered, non-ceramic material composed of small and large crystals and hydrophilic clusters with a controlled, predictable rate of resorption based on the patient’s age and metabolism. 

As opposed to particulate grafting materials on the market today, the plugs and strips prevent the migration of the OsteoGen crystals from the recipient’s surgical site by binding the crystals with collagen. With an approximate ratio of 60/40 mineral to collagen, it is similar to the makeup of native bone, and the distribution of OsteoGen crystals to porous collagen matrix creates an environment conducive to angiogenesis, cell proliferation, and new bone growth. The bioactive definition relates to the nature of the graft’s ability to form new bone by controlling migration of connective tissue and releasing calcium ions to stimulate new bone formation.

One of the main advantages of OsteoGen bioactive crystals is the ability to provide Ca⁺ ions directly into the site where bone growth and maturation will occur. When the composite is fully saturated with blood, these ions are released at an optimal level to facilitate healthy bone regeneration. 

Local Ca⁺ levels in the grafted area control osteoblastic viability, proliferation, and differentiation and are concentration-dependent.

• Too high: >10mM results in apoptosis.
• Optimum: 6 to 8mM results in proliferation.
• Too low: 2 to 4mM results in proliferation and survival without differentiation.

Various clinical studies and recently published papers have confirmed OsteoGen’s bioactivity.

In a split-mouth study conducted by Yosouf et al,¹⁸ it was shown that, when compared to healing without a graft (control), ridge preservation was greatly enhanced by the use of an OsteoGen Plug. Results showed a 60% improvement when grafting with an OsteoGen Plug as 0.56 mm was lost vertically with the plug compared to 1.47 mm lost in the control. When looking at horizontal grafting, 0.9 mm was lost horizontally compared to 2.26 mm in the control. This minimal amount of bone loss is comparable to levels lost when utilizing an allograft and a membrane,¹⁹ although Yosouf et al¹⁸ achieved these results with the use of a Plug alone and no membrane. 

Jones et al²⁰ directly compared an OsteoGen Plug to a Collagen Xenograft Plug (Salvin Dental Specialties) and human bone allograft. It was found that osteoblast proliferation throughout the OsteoGen Plug was between 3 and 6 times greater compared to the xenograft plug or allograft. Additionally, live cell images showed significantly greater osteoblast activity at multiple time periods compared to the xenograft material, which could not sustain the cells. Also, this study showed significantly higher porosity levels (94.4%) for the OsteoGen Plug compared to xenograft material (75.2%) and allograft (55.8%). The study concluded that the OsteoGen Plug demonstrated significantly better biocompatibility compared to the xenograft option and the allograft option alone. 

Jafarian²¹ compared the bone quality attained when using an OsteoGen Plug without a membrane to the bone quality attained using Biohorizons’ MinerOss corticocancellous allograft particulates and a dense PTFE membrane. The author concluded that there was no significant difference in bone quality measured by histomorphometry for placing an implant at 3 to 5 months between the OsteoGen Plug without a membrane and the current gold standard of corticocancellous allograft covered with a membrane.²⁰

The following case series will reinforce the literature with regard to the uses and results of this alloplast plug.

RIDGE PRESERVATION

The most common observation of insufficient quantity of bone in dentistry is following tooth loss, where rapid resorption of alveolar bone occurs due to an absence of intraosseous stimulation that would typically occur via the periodontal ligament fibers.^1,22,23 The amount of resorption is greatly dependent upon the reason for the extraction and the length of time pathology has been present. Studies and anecdotal clinical evidence provide the rationale for grafting fresh extraction sockets. 

During the first year after tooth loss, a patient can see possibly 40% to 60% of the width and height of the alveolar ridge resorb after tooth extraction. Preserving the alveolar ridge offers patients choices in their restorative treatment plans, including endosseous implants.²⁴

All successful ridge preservations have a common starting point, and that is the atraumatic extraction.²⁵ There are a plethora of instruments available, and practitioners use just as many techniques to remove teeth. Though the specific techniques to achieve this will not be discussed in detail, the result by the use of any instrument or technique should minimize soft- and hard-tissue trauma.

SOCKET PRESERVATION CASE 

The patient presented with a non-restorable maxillary right second molar (Figure 7a). Although the patient would likely not suffer any functional deficiency when chewing, he chose to have the site grafted in order to keep the possibilities open for an implant placement at a later date. After sectioning the roots for a less traumatic extraction (Figure 7b), the individual roots were removed while being careful not to damage the buccal plate (Figure 7c).

Figure 7. Socket preservation case.

Once the roots were removed, the sockets were thoroughly debrided to not only clean out any granulation tissue but also to produce copious bleeding. This bleeding is extremely important to kick off healing through what is known as the Regional Acceleratory Phenomenon by making holes through the lamina dura into cancellous bone and recruiting osteoclast cells. The OsteoGen Plug was then cut with scissors (Figure 7d) into a 3-root-like plug and placed into the socket (Figure 7e). The blood was allowed to soak into the plug by compacting the plug very gently into the socket to allow it to conform to the site (Figure 7f). A figure 8 chromic gut suture was utilized to hold the plug in place (Figure 7g). A primary closure or use of a membrane was not necessary. The compacted plug creates a bioactive-crystal, “wall-like” membrane to control the downward migration of connective tissue. 

A radiograph taken immediately post-op showed that the plug itself was radiolucent (Figure 7h) and would become more radio-opaque as it was replaced by native bone. This unique aspect allows a practitioner to easily know when the site is ready for further treatment.

An intraoral photo of the site at one month demonstrates the complete closure of the site by secondary healing (Figure 7i). The 3.5-month radiograph is indicative of how the socket radio-opacity changes during healing by showing bony reconstruction of the socket (Figure 7j).

GRAFTING THE GAP WITH IMMEDIATE IMPLANT PLACEMENT

Much has been written regarding how to manage the “gap” that results when an implant is placed in an extraction socket. When a dental implant is placed into a fresh extraction socket, the space between the implant periphery and surrounding bone is called the “gap” or “jumping distance.” Bone filling in the gap between the implant and the peripheral bone is important for integration and long-term success. The buccal aspect of an implant is of great concern, especially in the aesthetic zone, because the buccal bony plate is usually thin, and its resorption can result in soft-tissue recession.¹⁷

The horizontal gap, if less than 2 mm, will likely fill in without any intervention by the practitioner. In fact, it has been shown that it is possible to have complete fill-in with a gap of up to 4.2 mm, but this is not predictable. Due to this unpredictability, grafting the gap is a belt-and-suspenders approach to assuring that both hard and soft tissue remain stable through the healing process and result in the optimal aesthetics when treatment is completed.²⁶ 

In 2012, Chu et al²⁷ showed that the most predictable hard- and soft-tissue changes and aesthetic results when immediately placing implants in a fresh extraction socket occurs when the gap between the implant and the alveolus is grafted. 

IMMEDIATE PLACEMENT CASE 

Presenting with a failing maxillary right central (Figure 8a), this patient opted for extraction and immediate placement of an implant. After an atraumatic extraction of the tooth (Figure 8b), the tooth was evaluated to determine the amount and position of graft material to be placed. By laying an osteotomy bur on the root, this calculation is very easy to perform (Figure 8c).

Figure 8. Immediate placement case.

The osteotomy was prepared following standard protocol to ensure proper prosthetic position, and the site was checked for any inadvertent perforation. A portion of an OsteoGen Strip was rehydrated with sterile saline in preparation for use. As opposed to the plug, which is delivered dry into an extraction socket, the OsteoGen Strip is rehydrated beforehand to enhance its moldability to fill the gap between the implant body and the alveolus (Figure 8d). 

The position of the implant preparation had been distalized to take advantage of bone contact on the distal wall of the socket and to place the long axis of the implant in the correct prosthetic position for a central incisor with a midline diastema (Figure 8e). After placement of the strip, the implant was driven into place, causing the moldable strip to fill in any gaps (Figure 8f). Placing the strip first will be easier in these kinds of cases rather than trying to place it after the implant is in place. A check film was taken to verify the position (Figure 8g) and show the area of graft placement in the remaining socket. A 3-mm-tall healing abutment was placed, and the site was sutured with PGA sutures (Figure 8h). At the time of placement, the stability was not at a level that would have allowed for direct, immediate temporization. 

After 3.5 months of healing, the healing abutment was removed (Figure 8i), a digital impression post was placed, and the site was scanned for the final restoration. A custom titanium abutment with a full zirconium restoration was chosen for the final restoration and delivered a few weeks later (Figure 8j). The soft-tissue quantity and quality was excellent, and the patient was pleased with the outcome. 

SINUS ELEVATION

Everything from autogenous bone to allografts, xenografts, and alloplasts has been successfully used as graft material in the sinus. The osteoconductive activity of various bone substitutes has been assessed according to the quality and quantity of newly formed bone in the augmented areas.^28,29

The successful use of OsteoGen crystals in sinus elevation has been well-established for more than 30 years. In 1991, Wagner³⁰ showed the efficacy of this material in a 3.5-year follow-up study, and Manso and Wassal¹⁷ expanded on this work with a 10-year longitudinal study.The introduction of OsteoGen Plugs and Strips simplifies both vertical and lateral approach subantral lifts. The issues of material migration due to settling or loss due to the presence of a perforation have been mitigated due to the collagen makeup of the products. 

The use of these products as a graft material is independent of the type of lift or technique used. Either plugs, strips, or malleable OsteoGen blocks can be used depending on the clinical situation. This author prefers to use plugs for vertical lifts and strips for lateral approach lifts. 

SUBANTRAL AND LATERAL SINUS LIFTS 

In this case, the sinus floor needed a sub-5-mm lift to accommodate the apex of the implant to be placed (Figure 9a). An osteotome was used to up-fracture the floor after creating an osteotomy approximately 1 mm short of the sinus floor. A regular-size OsteoGen Plug (Figure 9b) was cut to the appropriate dimension needed for the lift (Figure 9c) and placed into the osteotomy using an osteotome (Figure 9d). The resulting lift showed a smooth membrane without any indications of a tear (Figure 9e). With the use of these plugs, even if there was a small perforation or tear, the plug would allow for healing of the Schneiderian membrane without loss of the graft. 

The Caldwell-Luc procedure, or lateral approach lift, is used when the clinical amount of crestal bone is less than 3 to 4 mm and placement of an implant would result in very little stability or exposure into the sinus cavity. The use of OsteoGen Strips rather than plugs to graft this type of case was decided upon in order to allow better conforming to the walls of the sinus cavity. 

Figure 9. Sinus elevation cases.

In this case, the sinus had pneumatized after extraction of the maxillary right first molar (Figure 9f) and required a lift of approximately 10 mm to accommodate the length of the intended implant to be placed. 

After a window was cut in the lateral wall of the sinus with a #2 round diamond (Figure 9g), the OsteoGen Strips were soaked in sterile saline (Figures 9h and 9i) to rehydrate them and make them malleable. Strips are first placed against the medial wall, then superiorly (Figure 9j), anteriorly, and posteriorly. This ensures that there will be grafting material 360° around the implant (Figures 9k and 9l) prior to placing additional strips laterally.

The final radiograph, taken 4 months later, indicated the growth of bone around the implant and the successful lift (Figure 9m). 

CONCLUSION

Many times, it is a patient preference or refusal of a material that will guide a practitioner toward the type of grafting material he or she can use in a case. Studies have shown the highest rate of refusal was observed for allografts and xenografts. The grafts with the lowest rates of refusal were autologous grafts (3%) and dense alloplastics (2%).³¹ 

An advanced composite graft material such as OsteoGen, in all its prefabricated shapes and formulations, has the advantages of ease of use, cost-effectiveness, clinical ease of delivery, and adaptability to its intended site when compared to the other grafting particulate options on the market today. It is a viable and, in many circumstances, a better long-term option for grafting than traditionally used xenografts and allografts. 

Currently, and in the future, combining this product with growth mediators such as PRF or other substances will open new chapters of outstanding clinical results. It is very likely that, in the future, the use of allografts and xenografts will likely diminish, and alloplastic bioactive materials, which have high quality, safety, and ease of clinical delivery, will be the regenerative materials of choice.

REFERENCES

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ABOUT THE AUTHOR

Dr. Schlesinger has been placing implants for the past 28 years, and as an educator for the past 19 years, he has taught doctors worldwide about dental surgical procedures. Along with running a busy private practice in Rio Rancho, NM, he maintains a clinical advisory role with numerous dental product manufacturers. He can be reached at  cdschlesinger@gmail.com. 

Adj. Prof. Valen is the founder and CEO of Impladent. He can be reached at maurice@impladentltd.com. 

Disclosure: Dr. Schlesinger is a paid consultant for Impladent. Mr. Valen is a nonpaid consultant for Solmetex and CEO of Impladent.

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Osseointegration, as defined by Brånemark, is a direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant.¹ The process of osseointegration is very much dependent on the quantity and composition of osteoblast attachment to the implant surface. The quantity of osteogenic cells in contact with the titanium surface directly correlates to the amount of peri-implant bone and, as a result, the percentage of bone to implant contact (BIC). Extracellular proteins such as fibronectin are integral in the attraction and attachment of osteoblasts to the titanium surface.² The aging of titanium results in the deposition of hydrocarbons on the surface, hydrophobicity, and conversion of the surface charge from positive to negative.³ This diminishes the bioactivity of the titanium so that proteins have less of an affinity for the implant surface and, consequently, inferior osteoblast proliferation, migration, and attachment compared to new titanium.³ The percentage of BIC is highly dependent on the bioactivity of the implant surface and its ability to interact biologically with the host’s mediators of osteogenesis.^4,5 The osseointegration speed index (OSI), as measured by sequential implant stability quotients (ISQs), is also affected by the decreased bioactivity. This process has been researched and reported, and the ISQ is generally expected to be adequate at 3 to 6 months, depending upon the bone quality or type and characteristics of the implant surface.^6-8 Implant surfaces have been modified over the years to enhance osseointegration by various methods, including plasma spraying, acid etching, or sandblasting the surface to gain improved adhesion, migration, and differentiation of osteoblasts, which increased the OSI and BIC.^7,8 However, these modifications to the implant surface design do not prevent the accumulation of hydrocarbons on the titanium implant surface that occurs with aging.^8-10 Aged titanium surfaces show less protein absorption (fibronectin, albumin) and consequently inferior osteoblast proliferation, migration, and attachment than a newly manufactured titanium implant.¹¹ This results in a decrease in both the BIC and the biomechanical strength of the bone-titanium interface.^10,12-14 A titanium implant that has aged has a BIC of 58%, whereas a newly manufactured implant has BIC of 90%.^10,12-14

Modification of the aged implant surface is clinically desirable to increase the OSI and BIC through the reversal of titanium degradation caused by aging. A novel surface treatment termed photofunctionalization (PFZ) has been shown to accomplish this modification.^10,14-22 The process of PFZ removes hydrocarbons, restores hydrophilicity, alters physiochemical properties, and restores bioactivity.

This article will present a case of UVCL treatment of a dental implant for the enhancement of the osseointegration process, reducing the functional osseointegration time from 12 to 16 weeks to 6 weeks.

CASE REPORT

A 47-year-old female patient reported to the Midwestern University College of Dental Medicine for replacement of her missing tooth No. 19. Restorative options, including fixed, removable, and implant-borne prosthetics, were presented, and the patient chose a dental implant. Her medical history was non-contributory, with no history of diabetes, tobacco use, or any immunosuppressant or anti-resorptive therapy and no past or present history of periodontal disease. She exhibited good oral home care and was committed to professional maintenance care every 4 months. She had lost tooth No. 19 from a periapical infection due to recurrent decay under a restoration she had received years ago. Tooth No. 19 was extracted without complication, followed by ridge preservation using mineralized/demineralized cortico-cancellous bone allograft (AlloOss [ACE Surgical Supply]) 7 months prior to implant placement surgery (Figure 1). 

Figure 1. Residual ridge No. 19 seven months post extraction and ridge preservation.

Figure 2. CBCT scan showing residual ridge No. 19 seven months post extraction and ridge preservation.

Figure 3. The implant workup from the DIOnavi dental laboratory (DIO Implant).

Figure 4. Surgical guide fabricated for the case.

Figure 5. DIOnavi drilling sequence provided by the laboratory.

Figure 6. DIOnavi UVC vacuum light.

Figure 7. Implant with healing abutment immediately after placement.

Figure 8. Restored implant.

A full maxillary and mandibular CBCT scan was acquired (3D Accuitomo 170 [J Morita]) (Figure 2) as well as intraoral scans (Emerald S scanners [Planmeca]), and the case was worked up in Romexis (version 6.3) implant planning software (Planmeca) to determine implant placement viability from a restoratively driven perspective. After that initial workup proved favorable, all data were electronically uploaded to the DIOnavi (DIO Implant, Busan, South Korea) portal for implant placement design and surgical guide fabrication (Figures 3 and 4). On the day of surgery, the DIO drilling protocol was followed (Figure 5). Before placement, the implant body was treated in a novel UVC vacuum light (DIO Implant) (Figure 6). A 5.0- × 11.5-mm DIO implant fixture was placed in site No. 19 with a seating insertion torque value of 50 Ncm. For investigative purposes, a CBCT scan was again taken on the day of implant placement (Figure 7), confirming the implant to be in a favorable position for restoration. At the 6-week mark, the patient returned; the healing abutment was removed; and ISQ readings were taken from the mesial, distal, buccal, and lingual, all registering at 85 (Osstell). The healing abutment was replaced, and the patient was then scheduled to begin the restorative phase of treatment at 6 weeks post implant placement. The final restoration is seen in Figure 8. 

DISCUSSION 

Ultraviolet light (UVL) is a form of radiation found on the electromagnetic spectrum. The spectrum consists of light types based on their wavelengths. These are radio, microwave, infrared, visible, ultraviolet A, ultraviolet B, ultraviolet C, x-ray, and gamma-ray waves. These wavelengths vary across the spectrum, with radio waves having the longest and gamma rays having the shortest. UVL is shorter than visible light, so it is invisible to most vertebrates, including humans, and the wavelengths range from 200 to 400 nm within this spectrum (Figures 9 and 10). In 1997, Wang et al,²³ reported on the effects of UVL on the superhydrophilicity of TiO₂, and applications were developed in many areas of industry, including anti-fogging, stain resistance, and antibacterial treatments, because of this research.²⁴ Funato and Ogawa²⁵ were the first to publish on the clinical application of PFZ to alter the surface of a titanium implant in 2013. Their study followed 7 implants that had micro-roughened surfaces that were photofunctionalized through exposure to UVL for 15 minutes chairside. All 7 implants were loaded early, and it was found that their ISQ values increased from insertion to loading. At one year, they found that all implants were integrated and under function after early loading. Funato et al²⁶ researched the effects of PFZ through a retrospective study. They found that healing times can be shortened to 3.2 months from 6.6 months using PFZ, effectively increasing the OSI. The work of Suzuki et al²⁷ has also shown that PFZ increases the OSI. While these reports showed clinical promise in the use of PFZ, 15 minutes to modify an implant chairside is not clinically applicable. However, research has continued, and a novel UVL activator (Figure 6) is now available to photofunctionalize implants chairside, according to the manufacturer (DIO Implant). This activator utilizes a 172-nm xenon excimer-generated vacuum ultraviolet light (VUV). The implants are stored in quartz ampules following manufacturing and subsequently modified in the VUV activator in these ampules as the quartz allows for the UVC light to exert maximum effect. This activator was tested against other commercially available devices, and it was found to accomplish greater than 90% decomposition of organic materials in the form of hydrocarbons.²⁸ PFZ allows for the reversal of titanium degradation, and this restores the TiO₂ layer, which restores bioactivity. Hydrocarbons are removed, hydrophilicity is restored, and the surface charge returns to positive. This, in turn, promotes protein adsorption, which enhances osteoblast migration, proliferation, and attachment to the implant surface. This results in improved biomechanical strength of the bone implant interface through increased BIC.²⁹ By accomplishing this, the osseointegration stability curve is shifted to the left (Figures 11 and 12).

Figure 9. Partial light spectrum in nanometers.

Figure 10. Ultraviolet light spectrum information.

Figure 11. Typical stability curve associated with osseointegration.

Figure 12. Stability curve demonstrating the shift to left for UVL-treated implants.

CONCLUSION

This case demonstrates the successful implementation of a novel UVL activator in modifying a dental implant surface. In addition, this shows that it may be clinically applicable to photofunctionalize dental implants chairside and, as a result, increase the BIC and the OSI, effectively shortening treatment time and providing predictable results.

REFERENCES 

1. Park NI, Kerr M. Chapter 2: Terminology in implant dentistry. In: Resnick R, ed. Misch’s Contemporary Implant Dentistry. 4th ed. Elsevier; 2020:20–2. 

2. Hori N, Att W, Ueno T, et al. Age-dependent degradation of the protein adsorption capacity of titanium. J Dent Res. 2009;88(7):663–7. doi:10.1177/0022034509339567 

3. Sugita Y, Saruta J, Taniyama T, et al. UV-pre-treated and protein-adsorbed titanium implants exhibit enhanced osteoconductivity. Int J Mol Sci. 2020;21(12):4194. doi:10.3390/ijms21124194 

4. Lian Z, Guan H, Ivanovski S, et al. Effect of bone to implant contact percentage on bone remodelling surrounding a dental implant. Int J Oral Maxillofac Surg. 2010;39(7):690–8. doi:10.1016/j.ijom.2010.03.020 

5. Pyo SW, Park YB, Moon HS, et al. Photofunctionalization enhances bone-implant contact, dynamics of interfacial osteogenesis, marginal bone seal, and removal torque value of implants: a dog jawbone study. Implant Dent. 2013;22(6):666–75. doi:10.1097/ID.0000000000000003 

6. Colnot C, Romero DM, Huang S, et al. Molecular analysis of healing at a bone-implant interface. J Dent Res. 2007;86(9):862–7. doi:10.1177/154405910708600911 

7. Davies JE. Understanding peri-implant endosseous healing. J Dent Educ. 2003;67(8):932–49. 

8. Misch C. Dental Implant Prosthetics. 2nd ed. Mosby; 2015.

9. Albrektsson T, Zarb G, Worthington P, et al. The long-term efficacy of currently used dental implants: a review and proposed criteria of success. Int J Oral Maxillofac Implants. 1986;1(1):11-25. 

10. Att W, Ogawa T. Biological aging of implant surfaces and their restoration with ultraviolet light treatment: a novel understanding of osseointegration. Int J Oral Maxillofac Implants. 2012;27(4):753–61.

11. Att W, Hori N, Takeuchi M, et al. Time-dependent degradation of titanium osteoconductivity: an implication of biological aging of implant materials. Biomaterials. 2009;30(29):5352–63. doi:10.1016/j.biomaterials.2009.06.040 

12. Hori N, Att W, Ueno T, et al. Age-dependent degradation of the protein adsorption capacity of titanium. J Dent Res. 2009;88(7):663–7. doi:10.1177/0022034509339567 

13. Att W, Hori N, Takeuchi M, et al. Time-dependent degradation of titanium osteoconductivity: an implication of biological aging of implant materials. Biomaterials. 2009;30(29):5352–63. doi:10.1016/j.biomaterials.2009.06.040 

14. Hirota M, Ozawa T, Iwai T, et al. UV-mediated photofunctionalization of dental implant: a seven-year results of a prospective study. J Clin Med. 2020;9(9):2733. doi:10.3390/jcm9092733 

15. Takeuchi M, Anpo M. Effect of UV light irradiation of different wavelengths on the surface wettability of titanium metal for dental implants. J Mater Sci Res. 2018. doi:10.29011/ JMSR-109/100009

16. Huang Y, Zhang H, Chen Z, et al. Improvement in osseointegration of titanium dental implants after exposure to ultraviolet-C light for varied durations: an experimental study in beagle dogs. J Oral Maxillofac Surg. 2022;80(8):1389–97. doi:10.1016/j.joms.2022.04.013

17. Chang LC. Clinical applications of photofunctionalization on dental implant surfaces: a narrative review. J Clin Med. 2022;11(19):5823. doi:10.3390/jcm11195823 

18. Arroyo-Lamas N, Arteagoitia I, Ugalde U. Surface activation of titanium dental implants by using UVC-LED irradiation. Int J Mol Sci. 2021;22(5):2597. doi:10.3390/ijms22052597 

19. Tabuchi M, Hamajima K, Tanaka M, et al. UV light-generated superhydrophilicity of a titanium surface enhances the transfer, diffusion and adsorption of osteogenic factors from a collagen sponge. Int J Mol Sci. 2021;22(13):6811. doi:10.3390/ijms22136811

20. Sugita Y, Saruta J, Taniyama T, et al. UV-pre-treated and protein-adsorbed titanium implants exhibit enhanced osteoconductivity. Int J Mol Sci. 2020;21(12):4194. doi:10.3390/ijms21124194 

21. Camolesi GCV, Somoza-Martín JM, Reboiras-López MD, et al. Photobiomodulation in dental implant stability and post-surgical healing and inflammation. A randomised double-blind study. Clin Oral Implants Res. 2023;34(2):137–47. doi:10.1111/clr.14026 

22. Suzuki S, Kobayashi H, Ogawa T. Implant stability change and osseointegration speed of immediately loaded photofunctionalized implants. Implant Dent. 2013;22(5):481–90. doi:10.1097/ID.0b013e31829deb62 

23. Wang R, Hashimoto K, Fujishima A, et al. Light-induced amphiphilic surfaces. Nature. 1997;388:431–2. doi:10.1038/41233

24. Aita H, Hori N, Takeuchi M, et al. The effect of ultraviolet functionalization of titanium on integration with bone. Biomaterials. 2009;30(6):1015–25. doi:10.1016/j.biomaterials.2008.11.004 

25. Funato A, Ogawa T. Photofunctionalized dental implants: a case series in compromised bone. Int J Oral Maxillofac Implants. 2013;28(6):1589–601. doi:10.11607/jomi.3232 

26. Funato A, Yamada M, Ogawa T. Success rate, healing time, and implant stability of photofunctionalized dental implants. Int J Oral Maxillofac Implants. 2013;28(5):1261–71. doi:10.11607/jomi.3263 

27. Suzuki S, Kobayashi H, Ogawa T. Implant stability change and osseointegration speed of immediately loaded photofunctionalized implants. Implant Dent. 2013;22(5):481–90. doi:10.1097/ID.0b013e31829deb62

28. Suzumura T, Matsuura T, Komatsu K, et al. A novel high-energy vacuum ultraviolet light photofunctionalization approach for decomposing organic molecules around titanium. Int J Mol Sci. 2023;24(3):1978. doi:10.3390/ijms24031978 

29. Pyo SW, Park YB, Moon HS, et al. Photofunctionalization enhances bone-implant contact, dynamics of interfacial osteogenesis, marginal bone seal, and removal torque value of implants: a dog jawbone study. Implant Dent. 2013;22(6):666–75. doi:10.1097/ID.0000000000000003 

ABOUT THE AUTHORS

Dr. Beals earned his BS, MS, and DDS degrees at The Ohio State University. He remained at Ohio State to complete a residency in oral and maxillofacial surgery, then relocated to Phoenix, where he entered private practice. He is currently a clinical associate professor at Midwestern University Dental Institute in Glendale, Ariz. He can be reached at dbeals@midwestern.edu.

Dr. Francis is a clinical associate professor at the College of Dental Medicine, Midwestern University in Glendale. He can be reached at jfranc@midwestern.edu.

Dr. Barber is a clinical associate professor at the College of Dental Medicine, Midwestern University. He can be reached at hbarbe@midwestern.edu.

Dr. Siu is a clinical associate professor at the College of Dental Medicine, Midwestern University. He can be reached via email at tsiu@midwestern.edu.

Dr. Cianciola is a clinical assistant professor at the College of Dental Medicine, Midwestern University. He can be reached at jcianc@midwestern.edu.

Disclosure: The authors report no disclosures. 

As dental implants continue to be the treatment of choice for many dentists and patients alike, and newer implant systems continue to emerge on the market, the importance of understanding the different implant connections available is imperative for a higher standard of care. 

To better understand implant connections, first we have to visualize the timeline of dental implants to see why there is a large variety of connections. Initially, Dr. Gustav Dahl designed subperiosteal implants as a framework placed over the residual ridge with projections resembling abutments as part of the framework for the definitive prosthesis. Later, Dr. Leonard Linkow introduced blade implants that were the first intraosseous implants but similar to a subperiosteal, with the abutment and implant as a unibody. Modern day implants designed by Professor Brånemark were installed for the first patient in 1965, and that was the birth of 2-piece implants and, by extension, implant connections.¹ 

The role of implant connections is to separate the abutment from the implant, thereby allowing us to modify and tailor our treatment methodology in reflection to each clinical presentation with the highest chances of success and survivability. Two-piece implants allow us to modify the design of the prosthesis over time and execute 2-stage surgeries when primary stability is insufficient, achieve primary closure for bone augmentation, and offer an opportunity for further soft tissue manipulation at second-stage surgery. Ultimately, every feature comes with a price; by design, the connection is an interface “microgap” that can be colonized by bacteria, causing bacterial leakage (Figure 1). The interface suffers from micromovements of the abutment under loading, acting as a micro pump for the bacteria into the surrounding tissue. In response, the bone remodels to establish a zone of defense, ie, biologic width. Different interface designs can significantly influence the remodeling of the muco-alveolar complex.² In response, clinicians and manufacturers poised and developed different designs of implant connections to minimize the drawbacks from a biologic, mechanical, and aesthetic perspective. While the landscape is vast in terms of shapes and sizes, the ideologies and concepts behind the connections are very simple (Table 1).

Figure 1. Microgap at the abutment-implant interface.

The first endosseous-design implants had an external connection. That is the first classification of implant connections: external and internal connections. It is important to note that some scientific papers refer to them as external and internal hex. In this context, “hex” means connection and does not refer to a hexagonal shape (Figure 2). 

Figure 2. (a) External hex: Brånemark External hex implant (Nobel Biocare). (b) Internal hex: Bone Level Tapered Implant (Straumann).

At that time, implants were used exclusively for full-arch prostheses to restore form and function for completely edentulous patients. The implant installation was followed by a period of 6 months of undisturbed healing; a second-stage surgery for insertion of a transmucosal healing abutment; and, finally, a definitive prosthesis. External connection implants functioned properly without limitations for that purpose, but as their success rates increased, clinicians began expanding their use to off-label indications: partially edentulous and single, missing teeth. Without the rigid fixation and splinting afforded by a full-arch prosthesis, we began experiencing the deficiencies of external connections for single crowns and FPDs: screw loosening (most common), screw fractures, and micromovement at the abutment-implant interface.³ By design, external connections lacked anti-rotation features, had low torquing levels of their prosthetic screws, and a looser fit at the connection level. There are different forms of external hex connections: hexagon, octagon, and spline, and over the years, they have been machined to respond to their inherent problems by adding/increasing friction grips to the hex, deeper screw engagement, wider screw diameters, higher screw torquing levels, and the number of threads. 

To overcome the inherent deficiencies of external connections, in 1998, internal connection implants were introduced to assist clinicians in replacing single teeth without external connection implants’ mechanical complications. Internal connections, by design, offered a larger surface area of contact between the abutment and implant as the connection moved inside the implant, improving the fit and minimizing rotational misfit (Figure 3). The longer engagement also created a stiffer, unified interface to resist joint opening, thereby reducing the pumping effect of microleakage and its biological consequences. Additionally, as the connection is bound by the body of the implant, it is able to dissipate the lateral forces within the body of the implants and the investing alveolar bone rather than in the abutment screw.^4-7

Figure 3. External and internal hex.

The second classification of implant connections derives from the geometric shape of the platform. Many designs exist on the market, most commonly hexagonal, octagonal, conical, trilobe, or a combination of these.^8,9 The variety of shapes affords different advantages in terms of passivity, anti-rotation, and microgap size. For example, the mean microgap was significantly larger for flat-to-flat (hexagonal or trilobe) connection systems when compared to conical (ie, Morse taper) connections.¹⁰ In true Morse taper connections, the abutment and implant are machined with a specific taper that is press fit together. Oftentimes, the abutments are tapped in rather than held with a screw. While Morse taper fosters the smallest microgap due to the profile and structural design of these connections, the abutments often fracture at the neck of the abutment and are much more difficult to remove when compared to conventional, non-Morse taper connections due to cold welding.^11,12 In response, implant manufacturers use a combination of designs to reap the benefits and minimize the drawbacks of different designs with a combination of connection geometry and position. Implants can be categorized as bone-level and tissue-level. Tissue-level implant platforms extend beyond the crest of bone, usually 1.8 to 2.8 mm above the crest with an internal connection. Bone-level implant platforms terminate at the crest of bone and may have an internal or external connection. 

The third classification of connections is engaging and non-engaging (Figure 4). Engaging connections, as the term implies, means the abutment has an anti-rotation feature, and the timing of the abutment is important as the definitive final crown can only fit in one specific orientation. With non-engaging abutments, the connection is free to rotate without a specific timing. Engaging abutments have a longer vertical height in the connection and are most commonly used for single crowns. Non-engaging abutments have a shorter vertical height connection and, therefore, are used for multiple-unit and full-arch restorations as it’s easier to have a passive fit of the definitive prosthesis when the implants are not fully parallel.

Figure 4. (a) Engaging and (b) non-engaging abutments.

Figure 5. Multi-unit abutments.

The final classification of connections is conventional abutments and multi-unit abutments (MUAs). Conventional abutments have a single screw holding the prosthesis, whether it is screw-retained or cement-retained. MUAs have 2 screws: one screw that holds the MUA onto the implant and another occlusal screw that retains the prosthesis to the MUA (Figure 5). MUAs are used for restorations involving more than one implant and can assist the clinician in correcting for variability in implant angulation and creating a more passive definitive prosthesis. 

SUMMARY

As the implant industry continues to evolve, it is essential to recognize that the fundamental principles of implant connections remain unchanged. While this article provides an overview of implant connections, it is not an exhaustive review. Its purpose is to equip readers with a basic understanding that enables them to ask pertinent questions and conduct further research in the field.

REFERENCES

1. Abraham CM. A brief historical perspective on dental implants, their surface coatings and treatments. Open Dent J. 2014;8:50–5. doi:10.2174/1874210601408010050 

2. Herrero-Climent M, Romero Ruiz MM, Díaz-Castro CM, et al. Influence of two different machined-collar heights on crestal bone loss. Int J Oral Maxillofac Implants. 2014;29(6):1374–9. doi:10.11607/jomi.3583 

3. Meng JC, Everts JE, Qian F, et al. Influence of connection geometry on dynamic micromotion at the implant-abutment interface. Int J Prosthodont. 2007;20(6):623–5. 

4. Binon PP. Implants and components: entering the new millennium. Int J Oral Maxillofac Implants. 2000;15(1):76-94.

5. Finger IM, Castellon P, Block M, et al. The evolution of external and internal implant/abutment connections. Pract Proced Aesthet Dent. 2003;15(8):625–32; quiz 634.  

6. Sailer I, Sailer T, Stawarczyk B, et al. In vitro study of the influence of the type of connection on the fracture load of zirconia abutments with internal and external implant-abutment connections. Int J Oral Maxillofac Implants. 2009;24(5):850–8. 

7. Da Silva EF, Pellizzer EP, Quinelli Mazaro JV, et al. Influence of the connector and implant design on the implant-tooth-connected prostheses. Clin Implant Dent Relat Res. 2010;12(3):254–62. doi:10.1111/j.1708-8208.2009.00161.x 

8. Coppedê AR, Bersani E, de Mattos Mda G, et al. Fracture resistance of the implant-abutment connection in implants with internal hex and internal conical connections under oblique compressive loading: an in vitro study. Int J Prosthodont. 2009;22(3):283–6. 

9. Delgado-Ruiz R, Silvente AN, Romanos G. Deformation of the internal connection of narrow implants after insertion in dense bone: an in vitro study. Materials (Basel). 2019;12(11):1833. doi:10.3390/ma12111833 

10. Akça K, Cehreli MC, Iplikçioğlu H. Evaluation of the mechanical characteristics of the implant-abutment complex of a reduced-diameter morse-taper implant. A nonlinear finite element stress analysis. Clin Oral Implants Res. 2003;14(4):444–54. doi:10.1034/j.1600-0501.2003.00828.x 

11. Baixe S, Fauxpoint G, Arntz Y, et al. Microgap between zirconia abutments and titanium implants. Int J Oral Maxillofac Implants. 2010;25(3):455–60. 

12. Ricciardi Coppedê A, de Mattos Mda G, Rodrigues RC, et al. Effect of repeated torque/mechanical loading cycles on two different abutment types in implants with internal tapered connections: an in vitro study. Clin Oral Implants Res. 2009;20(6):624–32. doi:10.1111/j.1600-0501.2008.01690.x

ABOUT THE AUTHOR

Dr. Barsoum completed his bachelor’s of dental medicine in 2012 at Misr International University in Cairo. He then graduated magna cum laude from Boston University, where he earned his DMD degree and later completed a 3-year residency and fellowship at New York University in the Ashman Department of Periodontics and Implant Dentistry, where he is also an adjunct assistant professor. Dr. Barsoum’s practice in New York City focuses on dental implants, prosthetics, and full-mouth rehabilitation. He can be reached at adam@barsoum.com or at his practice’s website, nyc.barsoum.com.

Disclosure: Dr. Barsoum reports no disclosures.  

Implant dentistry research has demonstrated high success rates in the reconstruction of partial and fully edentulous sites.¹ The placement of implants into fresh extraction sockets, known as immediate implant placement (IIP), was first described more than 50 years ago.^2,3 Today, it is widely accepted by the clinical community because IIP shares comparable survival rates to those of implants placed in healing sockets.^4-7 The IIP approach can streamline the surgical and prosthetic stages, reducing appointments and overall treatment time.⁸ Extended treatment times may impact patient decisions toward faster treatment rather than ideal treatment.  

IIP in the posterior maxilla requires an in-depth knowledge of several surgical and prosthetic techniques. The approach includes extraction, implant placement, final impression taking, guided bone regeneration, and placement of an implant restoration. In addition, sinus augmentation and growth factors in platelet concentrates may be needed as part of the skill set of the clinician to enhance hard- and soft-tissue healing.^9-11  

After an osseointegration period, the final abutment and restoration are placed. The entire process is completed in 2 appointments, including a single surgery within a 3- to 4-month time interval. The time period prior to loading is determined by several factors, including bone quality and quantity, biomechanics, and occlusion. IIP in the posterior maxillary molar sites is more challenging than using this approach in single-rooted teeth.¹²  

This article discusses a specific approach for the management of a maxillary molar with a poor prognosis. The IIP case demonstrates the surgical and prosthetic protocol for a posterior maxillary molar tooth. Research discussing this clinical scenario is limited in the body of evidence.  

CASE REPORT 

A 58-year-old female patient was referred by an endodontist for extraction and a restorative treatment plan. A diagnosis of apical periodontitis with a vertical root fracture was made for the maxillary left first molar (tooth No. 14). The clinical and radiographic evaluation demonstrated an existing porcelain-fused-to-metal crown and previous endodontic therapy. The periapical and CBCT imaging revealed a large periapical radiolucency (Figures 1 to 3).   

Figure 1. Periapical radiograph of the maxillary left first molar (tooth No. 14).

Figure 2. CBCT image, sagittal view.

Figure 3. CBCT image, sagittal view.

The surgical phase was initiated with a 20-mL whole blood draw via the median cubital vein. Buffy coat platelet-rich plasma (BC-PRP) and platelet-rich fibrin (PRF) were produced in a single spin centrifuge, centrifuged at 3,100 rpm for 12 minutes, and processed (Figure 4). Local anesthesia (1 carpule 3% Polocaine without epinephrine [54 mg] and 1 carpule 4% Articaine with 1:100,000 epinephrine [72mg] [Benco Dental]) was administrated. An intrasulcular incision utilizing a 15c blade was made. Then Nos. 1 and 2 periotomes, and sectioning of the mesial/buccal, distal/buccal, and palatal roots with a No. 4 long shank round bur were performed. A universal forceps was used to remove 3 individual roots, followed by thorough debridement of the tooth socket with a double-ended molt curette and irrigation with 10% Povidone solution.  

Figure 4. Platelet-rich fibrin.

A 4.7- × 13-mm SBM tapered implant (Legacy1 [Implant Direct]) was placed with a straight driver. Prior to implant placement, the osteotomy and internal sinus augmentation were performed with Densah osseodensification drills (OD) (Versah [Huwais IP Holding]) (Figure 5). A 1.6-mm pilot drill rotating clockwise (forward) initiated the osteotomy, followed by 2.0-, 2.5- and 3.0-mm Densah drills rotating in a counterclockwise (reverse) movement. The final OD drill size was 4.0 mm in diameter and extended 2 mm apical to the sinus floor. A PRF bioactive plug was placed in the osteotomy, followed by a mixture of BC-PRP and mineralized irradiated bone allograph (perio [Rocky Mountain Tissue Bank]). The grafting materials utilized in the crestal (internal) sinus augmentation were introduced into the osteotomy with a 3.8-mm straight osteotome. A fixture-level impression was taken with a 4.7-mm concave transfer pin. Following the impression, the transfer pin was removed and replaced with a 4.7- × 3-mm healing collar. The gap space between the implant surface and socket wall was grafted with BC-PRP and mineralized irradiated bone allograph (Rocky Mountain Tissue Bank) of fine particle size ranging from 250 to 1,000 µm. The graft material was placed in the gingival sulcus up to the free gingival margin. A non-resorbable d-PTFE barrier (Cytoplast [Implant Direct]) was secured over the healing collar with 4.0 Vicryl sutures, and a periapical radiograph was taken (Figures 6 and 7).   

Figure 5. A 3.0-mm Densah drill (Versah).

Figure 6. A d-PTFE non-resorbable barrier.

Figure 7. Periapical radiograph of the fixture/healing collar.

After 4 months, the healing collar was removed (Figure 8). A titanium abutment was placed utilizing an orientation jig and was followed by a periapical radiograph (Figures 9 and 10). The abutment screw was torqued to 30 N/cm 2 times at 5-minute intervals (Figure 11). The definitive PFM crown was placed with a permanent cement (Zinc Phosphate [Bosworth Co]) (Figures 12 and 13).  

Figure 8. Healing collar.

Figure 9. Orientation jig.

Figure 10. Periapical radiograph, abutment.

Figure 11. Titanium abutment.

Figure 12. Final prosthesis, porcelain-fused-to-metal crown (occlusal view).

Figure 13. Final prosthesis, porcelain-fused-to-metal crown (facial view).

DISCUSSION

The IIP approach differs from the conventional implant surgical approach employed since the inception of endosseous implant therapy. However, IIP demonstrates similar success rates of greater than 98% to the staged implant approach. Recently, the IIP approach in the posterior maxilla has been more widely utilized because of innovative instrumentation, implant design, and surface characteristics.¹³ IIP procedures are more challenging in the posterior maxillary regions due to the quality and quantity of bone, as well as the presence of anatomical structures. However, the majority of IIP principles and protocols are similar with subtle differences depending on whether they are utilized in the anterior or posterior region of the mouth.  

The surgical aspect of IIP in the maxillary molar region is initiated with a flapless, atraumatic extraction of the tooth. It is accomplished by expansion of bone, sectioning, and removal of 3 individual root fragments. This extraction approach allows for the removal of the tooth while maintaining the bone volume needed for primary fixation of the implant body. Primary fixation is the primary objective of the implant surgical placement stage. The ideal position and stability of the implant can be best achieved utilizing a CBCT-generated guide or ODs or by preparing the osteotomy through the residual root.^14-16 The trajectory of the osteotomy is in an apical-palatal direction to enhance primary stability.¹⁷   

Implant surgical placement in the posterior maxillary aspect often requires simultaneous sinus augmentation. Osseodensification instrumentation facilitates the expansion of soft bone and a reduction in membrane perforations, which enhance positive outcomes.¹⁸ The osseodensification technique has demonstrated an increase in implant primary stability, bone mineral density, and the preservation of bone at the implant surface. Osseodensification preserves bone volume through compaction of cancellous bone due to the natural properties of viscoelasticity and plastic deformation.¹⁹ Primary stability and preservation of bone bulk in low-density bone and the reduction in micromotion directly impacts the healing process.^20,21  

A torque value greater than 45 N/cm is not required in the molar region, only a lack of movement or spinning of the implant fixture because a provisional crown is usually utilized in the anterior or aesthetic zone. A healing collar is placed over the fixture in the posterior non-aesthetic zone during the osseointegrative phase. 

The gap that exists between the socket wall and implant surface can be managed with various procedures and materials. Platelet concentrates and allographic bone are common components associated with a crestal (internal) sinus augmentation and gap management. A single platelet contains more than 1,000 growth factors, including platelet-derived growth factor, transferring growth factors beta 1 and 2, and endothelial vascular growth factors. Growth factors have exhibited an increase in the recruitment, differentiation, and quantity of cells associated with tissue healing. BC-PRP is mixed with allographs to serve as a carrier or with PRF as a bioactive membrane for cell development. Allographic cadaver bone is commonly utilized in IIP due to its available quantities, safety, and osseoconductive properties.^22,23 In addition, allographic bone serves as an osseinductive source via bone morphogenic protein. A particle size of 250 to 1,000 µm used in this study was obtained from a human vertebral source and gamma-irradiated at 2.5 to 3.8 mrad to kill all bacteria, viruses, and cells.^24,25 Allogenic graft is made of scaffolds from human cadavers and processed to maintain structure and extracellular protein.²⁶ It is packaged in a hydrated form to increase strength and flexibility.²⁷ Studies have demonstrated that grafting the gap increases hard tissue.²⁸ Studies demonstrate that graft materials coronal to the implant platform to the free gingival margin enhance the thickness of soft tissue. Graft materials may alter the biotype or reduce the likelihood of a connective tissue graft.²⁹  

The restorative stage is initiated at the surgical appointment with a fixture-level impression. The impression can be taken with predictable results based on primary stability, proper 3D implant placement, and graft material placement in the gap as well as coronal to the connection to the top of the healing collar. The final restoration is delivered after an osseointegration period. A standard titanium abutment is placed, and its retaining screw is torqued to the appropriate value 2 times in a 5-minute time interval to ensure an intimate fit.³⁰ The final PFM restoration is placed with a permanent cement.  

Implant occlusal principles for the final restoration should exhibit zero contact during central occlusion, excursions, or protrusion. The buccal/palatal dimension of the occlusal table is reduced to mimic the size of a premolar. Occlusal table width is directly related to the applied force to the crest of bone. Therefore, a reduction in B/P dimension minimizes the force applied to the crest of the bone.³¹

ACKNOWLEDGMENTS

The author wishes to acknowledge Tatyana Lyubezhanina, DA, and LeeAnn Klotz, DA, for their assistance in preparation of this article.  

REFERENCES

1. Albrektsson T, Brånemark PI, Hansson HA, et al. Osseointegrated titanium implants. Requirements for ensuring a long-lasting, direct bone-to-implant anchorage in man. Acta Orthop Scand. 1981;52(2):155–70. doi:10.3109/17453678108991776 

2. Schulte W, Heimke G. Das Tübinger Sofort-Implant [The Tübinger immediate implant]. Quintessenz. 1976;27(6):17-23. German. 

3. Schulte W, Kleineikenscheidt H, Lindner K, et al. Das Tübinger Sofortimplantat in der klinischen Prüfung [The Tübingen immediate implant in clinical studies]. Dtsch Zahnarztl Z. 1978;33(5):348–59. German. 

4. Quirynen M, Van Assche N, Botticelli D, et al. How does the timing of implant placement to extraction affect outcome? Int J Oral Maxillofac Implants. 2007;22 Suppl:203–23. Erratum in: Int J Oral Maxillofac Implants. 2008;23(1):56.  

5. Schropp L, Isidor F. Timing of implant placement relative to tooth extraction. J Oral Rehabil. 2008;35(Suppl 1):33-43. doi:10.1111/j.1365-2842.2007.01827.x 

6. Becker W, Goldstein M. Immediate implant placement: treatment planning and surgical steps for successful outcome. Periodontol 2000. 2008;47:79-89. doi:10.1111/j.1600-0757.2007.00242.x 

7. Chen ST, Buser D. Clinical and esthetic outcomes of implants placed in postextraction sites. Int J Oral Maxillofac Implants. 2009;24(Suppl):186-217. 

8. Lazzara RJ. Immediate implant placement into extraction sites: surgical and restorative advantages. Int J Periodontics Restorative Dent. 1989;9(5):332–43.  

9. Jackson BJ. Proposed treatment approach for type II sockets: report of two cases. J Oral Implantol. 2019;45(3):227–34. doi:10.1563/aaid-joi-D-18-00148 

10. Summers RB. The osteotome technique: Part 3—Less invasive methods of elevating the sinus floor. Compendium. 1994;15(6):698-704. 

11. Rutkowski JL, Thomas JM, Bering CL, et al. An analysis of a rapid, simple, and inexpensive technique used to obtain platelet-rich plasma for use in clinical practice. J Oral Implantol. 2008;34(1):25-33. doi:10.1563/1548-1336(2008)34[25:AAOARS]2.0.CO;2 

12. Atieh MA, Payne AG, Duncan WJ, et al. Immediate placement or immediate restoration/loading of single implants for molar tooth replacement: a systematic review and meta-analysis. Int J Oral Maxillofac Implants. 2010;25(2):401–15.  

13. Lang NP, Pun L, Lau KY, et al. A systematic review on survival and success rates of implants placed immediately into fresh extraction sockets after at least 1 year. Clin Oral Implants Res. 2012;23(Suppl 5):39-66. doi:10.1111/j.1600-0501.2011.02372.x

14. Schneider D, Marquardt P, Zwahlen M, et al. A systematic review on the accuracy and the clinical outcome of computer-guided template-based implant dentistry. Clin Oral Implants Res. 2009;20(Suppl 4):73-86. doi:10.1111/j.1600-0501.2009.01788.x 

15. Davarpanah M, Szmukler-Moncler S. Unconventional implant treatment: I. Implant placement in contact with ankylosed root fragments. A series of five case reports. Clin Oral Implants Res. 2009;20(8):851–6. doi:10.1111/j.1600-0501.2008.01653.x 

16. Rebele SF, Zuhr O, Hürzeler MB. Pre-extractive interradicular implant bed preparation: case presentations of a novel approach to immediate implant placement at multirooted molar sites. Int J Periodontics Restorative Dent. 2013;33(1):89-96. doi:10.11607/prd.1444 

17. Lang NP, Berglundh T; Working Group 4 of Seventh European Workshop on Periodontology. Periimplant diseases: where are we now? Consensus of the Seventh European Workshop on Periodontology. J Clin Periodontol. 2011;38(Suppl 11):178–81. doi:10.1111/j.1600-051X.2010.01674.x 

18. Huwais S, Meyer EG. A novel osseous densification approach in implant osteotomy preparation to increase biomechanical primary stability, bone mineral density, and bone-to-implant contact. Int J Oral Maxillofac Implants. 2017;32(1):27-36. doi:10.11607/jomi.4817 

19. Pikos MA, Miron RJ. Osseodensification: An Overview of Scientific Rationale and Biological Background. Compend Contin Educ Dent. 2019;40(4):217–22. 

20. Trisi P, Berardini M, Falco A, et al. New osseodensification implant site preparation method to increase bone density in low-density bone: in vivo evaluation in sheep. Implant Dent. 2016;25(1):24-31. doi:10.1097/ID.0000000000000358 

21. Tabassum A, Meijer GJ, Walboomers XF, et al. Evaluation of primary and secondary stability of titanium implants using different surgical techniques. Clin Oral Implants Res. 2014;25(4):487–92. doi:10.1111/clr.12180 

22. Amstutz HC, Sissons HA. The structure of the vertebral spongiosa. J Bone Joint Surg Br. 1969;51(3):540–50. 

23. Elsharkawy AT, Sharaqy M, Beheiry MG, et al. Autologous versus allogeneic bone blocks for augmentation of maxillary deficiency. Egypt Dent J. 2013;59:4117–21.

24. Tatum OH Jr, Lebowitz MS, Tatum CA, et al. Sinus augmentation. Rationale, development, long-term results. N Y State Dent J. 1993;59(5):43–8. 

25. Tatum OH Jr. Osseous grafts in intra-oral sites. J Oral Implantol. 1996;22(1):51–2. 

26. Troeltzsch M, Troeltzsch M, Kauffmann P, et al. Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review. J Craniomaxillofac Surg. 2016;44(10):1618–29. doi:10.1016/j.jcms.2016.07.028 

27. Pabst A, Ackermann M, Thiem D, et al. Influence of different rehydration protocols on biomechanical properties of allogeneic cortical bone plates: a combined in-vitro/in-vivo study. J Invest Surg. 2021;34(10):1158–64. doi:10.1080/08941939.2020.1767735. Erratum in: J Invest Surg. 2020;1-2

28. Araújo MG, Linder E, Lindhe J. Bio-Oss collagen in the buccal gap at immediate implants: a 6-month study in the dog. Clin Oral Implants Res. 2011;22(1):1-8. doi:10.1111/j.1600-0501.2010.01920.x 

29. Chu SJ, Salama MA, Salama H, et al. The dual-zone therapeutic concept of managing immediate implant placement and provisional restoration in anterior extraction sockets. Compend Contin Educ Dent. 2012;33(7):524–32, 534. 

30. Winkler S, Ring K, Ring JD, et al. Implant screw mechanics and the settling effect: overview. J Oral Implantol. 2003;29(5):242–5. doi:10.1563/1548-1336(2003)029<0242:ISMATS>2.3.CO;2 

31. Misch CE. Chapter 31: Occlusal considerations for implant-supported prosthesis. In: Misch CE, ed. Contemporary Implant Dentistry. 2nd ed. Mosby; 1993:705–33.

ABOUT THE AUTHOR

Dr. Jackson graduated from Utica University with a BS degree in biology, cum laude. He received his DDS degree at the State University of New York at Buffalo School of Dental Medicine. Dr. Jackson completed postgraduate training at St. Luke’s Memorial Hospital Center’s General Practice Residency Program. He completed his formal implant training through the New York Maxicourse in Oral Implantology at the New York University College of Dentistry. He is board-certified and a Diplomate of the American Board of Oral Implantology/Implant Dentistry and an Honored Fellow of the American Academy of Implant Dentistry (AAID). Dr. Jackson is the past president of the AAID. He is an attending staff dentist for Faxton-St. Luke’s Healthcare General Practice Residency Program. He is a member of the ADA and director of the AAID Boston Maxicourse in Oral Implantology and the East Coast Implant Institute. Dr. Jackson has published several articles in peer-reviewed journals on the topic of oral implantology and implant dentistry. He can be reached at bjjddsimplant@aol.com. 

Disclosure: Dr. Jackson reports no disclosures.  

Replacement of incisors is a huge challenge for clinicians, technicians, and even patients, and although the advancements in dental implants and techniques made outcomes more predictable, proper management of the soft tissues and patients’ acceptance of results are still not guaranteed.¹ Moreover, patients facing the loss of their teeth may experience apprehension toward losing their social image or daily function. Hence, patients often expect to have their implants restored with a fixed prosthesis similar to their natural dentition much earlier during the treatment phase.² The preparation of aesthetically appealing and anatomically correct implant-supported provisional restorations facilitates the fabrication of the final implant-supported crown. The provisional restoration molds and manipulates the soft tissue while acting as a blueprint or template for the final crown.³ The emergence profile of the provisional restoration passes through stages of different forms. The first stage is concave to give space for the gingival tissues to grow in thickness.⁴ Later, resin material is added to exert some pressure on definite positions to move the gingival tissues to the desired levels. The soft-tissue form and position are stabilized, and the final provisional emergence profile form should be properly recorded. This is transferred to the dental laboratory for duplication to the final restoration.⁵ Immediately after removal of the provisional restoration, the peri-implant soft tissues begin to remodel into a flatter gingival architecture resembling that of an edentulous site. If no attempt is made to halt the soft-tissue remodeling when the provisional restoration is removed, the resulting cast will not accurately represent the soft-tissue contours around the provisional restoration,⁵ not to mention the challenges facing the ceramist in accurately reproducing hue, chroma, value, surface characterization, translucency, opacity, surface gloss, and internal as well as external characterizations.⁶

CASE REPORT

Chief Complaint and Addressing Challenges

A 28-year-old female patient presented to the Fixed Prosthodontics Department clinic in the Faculty of Dentistry at Ain Shams University in Cairo, Egypt, with missing tooth No. 9 that, due to a traumatic accident years ago, had been restored with an acrylic removable partial denture. She requested replacing the removable prosthesis with the most conservative fixed solution.

The clinical examination, radiographs, diagnostic casts, and photographs revealed a reduction in mesiodistal width of the edentulous space compared to tooth No. 8, a high lip-line, buccal hard- and soft-tissue defects, and challenging shades and textures of neighboring teeth (Figure 1). A CBCT scan confirmed the bone deficiency findings.

Figure 1. Preoperative photos. (a) The frontal and (b) occlusal view show the decreased mesiodistal width of the edentulous space of the missing upper left central incisor and the high lip-line of the patient.

Treatment Planning

After consultation with the surgeon, 3 options for restoration were presented. A dental implant, a resin-bonded bridge, and a fixed partial denture were clearly discussed, along with the pros and cons of each. She chose the grafting and implant solution as she didn’t want to sacrifice any sound tooth structure of the adjacent teeth. A diagnostic aesthetic wax-up for tooth No. 9 was created to be used later for prosthetic implant placement and provisionalization. An autogenous bone block graft from the patient’s mandible was used to increase the buccolingual dimension of the ridge (Figure 2). After 4 months, an implant (3.8 × 12 mm) (Maestro Dental Implant [BioHorizons]) was placed, aided by a surgical guide. Guided bone regeneration was done, and platelet-rich fibrin and connective tissue graft from the palatal mucosa were also transplanted to the donor’s site to augment the deficiency in soft-tissue structures. The patient returned after 10 days for suture removal and a provisional resin-bonded, fixed denture prosthesis construction. The tissue surface of the pontic was ensured not to exert any pressure on the healing site. In the second stage of surgery, the implant was exposed, and the provisional restoration was screwed onto the implant. Occlusion was adjusted on the crown so that it only shared the centric load and was free from all contacts in eccentric occlusion. The patient was scheduled for multiple visits 2 weeks apart to monitor the gingival shaping progress. Composite resin was added wherever needed and polished, and the provisional crown was screwed and tightened. Once the gingival level was considered satisfactory for both the clinician and the patient, it was time for a final impression (Figure 3).

Figure 2. An occlusal view showing the defect in the buccolingual dimension of the edentulous space.

Figure 3. Proper soft-tissue contour shaped by the emergence profile of the provisional restoration.

Final Restoration

The provisional restoration was used to construct a custom-made impression coping following the technique from Papadopoulos et al.⁷ First, the provisional was screwed to an implant analog (Figure 4a). An impression tray was fabricated for the analog using a piece of pink wax sheet rolled as a cylinder. A hard-consistency impression material was used to record the emergence profile of the provisional crown. The crown was removed and replaced with an impression coping (Figure 4b). The space previously occupied with the emergence profile of the provisional restoration was filled with Bisacryl temporary crown material (Figure 4c). After complete setting, the custom-made impression coping was unscrewed and finished (Figure 4d). The excess temporary material was removed, and the coping was tightened to the implant inside the patient’s mouth (Figure 5). The screw channel was blocked with Teflon, and a one-step impression technique was chosen. The impression coping was tightened to the analog, positioned in the impression, and sent to the dental laboratory with the diagnostic wax-up cast and a full set of photographs. A lithium disilicate (IPS e.max [Ivoclar]) hybrid abutment with a separate crown made by pressing technology and having the same emergence profile of the provisional and impression coping was fabricated for the case (Figure 6). The separate abutment and crown choice was made because of the frequent fracture of the provisional hybrid crown, indicating its exposure to high forces due to the palatal position of the implant. A medium-opacity ingot was selected for the abutment to block the titanium-base (Ti-base) metallic color, while a low-translucency ingot was chosen for the crown. After the try-in visit, the restorations were returned to the dental laboratory for glazing and hybrid abutment cementation to the titanium base. The Ti-base was sandblasted with 100-µm alumina particles. While fitting surfaces of the hybrid abutment, the screw channels were etched with a 9% hydrofluoric acid etchant (Porcelain Etch and Silane 9% buffered HF acid [Ultradent Products]) for 20 seconds, thoroughly rinsed, and dried before being treated with silane coupling agent (Porcelain Etch and Silane). Dual-cured adhesive resin cement (Multilink Automix [Ivoclar]) was used to bond the abutment and the Ti-base. The patient proceeded with the delivery visit, reinspected the crown, and approved it for final cementation.

Figure 4. (a) A temporary crown was mounted on analog and impression material and was used for recording the emergence profile. (b and c) The temporary crown was replaced with the impression coping, and flowable composite material was used to fill the space. (d) The custom implant impression coping.

Figure 5. Custom implant impression coping.

Figure 6. Copying the emergence profile from (a) the impression coping to (b) the wax pattern to (c) the final abutment.

Need for Modification

At this stage, the clinician and the patient noticed the more incisally aligned gingival margin of the ceramic crown that was overlooked in the temporary and try-in stages (Figure 7). Additional composite resin material was added to the labial emergence profile of the provisional crown to push the gingival tissues further apically. After 4 weeks, the new gingival level was stabilized, and a new impression was taken. After pouring the stone cast, the space around the abutment showed the amount of ceramic that needed to be added to adjust the gingival line, but as the abutment was cemented with resin cement to the Ti-base, the addition was impossible. The only solution seemed to be to remake the crown and the abutment!

Figure 7. The difference in gingival levels between the restored and the natural maxillary incisor.

The patient and clinician agreed upon keeping the crown, while the addition in the emergence profile of the abutment was built separately in wax, pressed, and luted to the ceramic abutment (Figures 8 and 9). Once the fit was confirmed, the piece was extraorally etched, silanated, and cemented to the hybrid abutment (Figures 10 and 11). The delivery process was completed by etching and silanizing the hybrid abutment and the fitting surface of the crown.

Figure 8. Spruing the wax piece intended to modify the emergence profile.

Figure 9. (a) The hybrid abutment on the cast showing the deficient emergence profile. (b) Here it is shown after pressing the added piece to the existing emergence profile and before cementation.

The abutment was screwed to the implant with 30 Ncm of force with a torque wrench, the screw channel was blocked with Teflon and light-cured composite resin, and the crown was finally cemented (Figure 12). The occlusion was adjusted so that, in light contact, the crown wouldn’t share in the centric occlusal load and would share only in the heavy biting. The eccentric contacts couldn’t be totally eliminated due to the protruded lower left central incisor, but the occlusion was adjusted so that it shared in heavy contact protrusive movements only. The patient was instructed to monitor the gingival condition and was given sufficient oral hygiene measures, scheduled for recall visits, and followed up for 36 months afterward (Figure 13).

Figure 10. The hybrid abutment after modification.

Figure 11. Intraoral photographs of the new gingival level exerted by the modified hybrid abutment: the (a) frontal and (b) occlusal view.

Figure 12. Immediate postoperative image.

Figure 13. (a) Periapical radiograph and (b) intraoral retracted view after a 36-month follow-up appointment.

DISCUSSION

Because of their proximity to one another that facilitates critical evaluation, a missing single central incisor can be the most challenging case for the clinician and technician but also the most rewarding. A dental implant is considered the first line of treatment in the case of single missing teeth and has the greatest success rate. In the aesthetic zone, osseointegration and function of a single implant are no longer the only criteria for determining success in state-of-the-art of implant dentistry. There must not only be osseointegration of single implants but also harmonious soft- and hard-tissue architecture complementing natural-looking implant restorations.⁸ To achieve optimal aesthetics regarding soft tissues, several issues have been taken into consideration recently, including implant-loading protocol, provisional restorations, aesthetic and biocompatible properties of restorative materials, the proper 3D implant placement, and gingival biotype.^9-14 An implant abutment emergence profile similar to that of a natural tooth is required to support and contour the peri-implant soft tissues. The circular, small-diameter implant, when compared to the root of a natural tooth, creates a dilemma of how to construct a restoration that imitates the natural tooth form.¹⁵ As implants have cylindrical form, it is impossible for restorations emerging from them to restore and maintain gingival margins to imitate those supported by anatomically correct, natural teeth.¹⁶ Soft-tissue management with provisional restorations utilizing the selective pressure method via provisional restorations is essential. As the soft tissues tend to slump and collapse in no time after provisional removal using a technique that ensures proper subgingival contours, recording is mandatory for fabricating a final restoration that supports the gingival tissues in the right position. One of these techniques involves indirectly replicating the subgingival contours of the provisional abutment in an impression material or autopolymerizing acrylic resin.^17,18 Since the platform size of the abutment typically matches that of the implant replacing the missing root, the resulting emergence profile of the final restoration will never replicate that of the natural tooth, making customization inevitable.¹⁹ The hybrid abutment is a ceramic abutment, which is luted to a Ti-base with a crown cemented on it. The Ti-base provides space for the pressed restoration required to adjust the shape, emergence profile, and aesthetic properties of this abutment according to the clinical situation.²⁰ With the preparation margin of the crown located on the gingival level, the geometry of the hybrid abutments allows for an easy integration of the restoration and excess cementation material is, therefore, easily removed.²⁰ In this case report, a modification in the subgingival contours was required after the ceramic abutment cementation to the Ti-base. The clinician had to remake the whole restoration or depend on the reliable hydrofluoric acid and silane coupling agent surface treatment for glass ceramics. A strong and durable resin bond provides high retention, improves marginal adaptation, prevents microleakage, and increases the fracture resistance of the restored tooth and the restoration, yielding durable results when guidelines are followed.²⁰

CONCLUSION

In cases with implant placement in the aesthetic zone, osseointegration alone cannot determine the success of a dental implant restoration. The challenges faced by the clinician and technician in each step to deliver a restoration that fulfils the patient’s needs aesthetically and functionally and maintains biological tissue health are innumerable. In this case, the maxillary central incisor was restored with a lithium disilicate hybrid abutment and crown. Surgical as well as prosthetic treatments were performed to restore white and pink aesthetics.

And after a 3-year followup, it was concluded that treatment using customized implant solutions with the modified emergence profile with bonded glass ceramics was satisfactory and stable.

ACKNOWLEDGMENT

The authors would like to express appreciation to Dr. Karim Abdelmohsen, assistant professor of oral and maxillofacial implants, faculty of dentistry, Ain Shams University, for performing the surgical procedures.

REFERENCES

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2. Santosa RE. Provisional restoration options in implant dentistry. Aust Dent J. 2007;52(3):234–42. doi:10.1111/j.1834-7819.2007.tb00494.x 

3. David R. Provisional restoration for an osseointegrated single maxillary anterior implant. J Can Dent Assoc. 2008;74(7):609–12. 

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6. Raigrodski A. Managing the challenge of crowning the single central maxillary incisor. J Esthet Restor Dent. 2008;20(5):337–42. doi:10.1111/j.1708-8240.2008.00206.x 

7. Papadopoulos I, Pozidi G, Goussias H, et al. Transferring the emergence profile from the provisional to the final restoration. J Esthet Restor Dent. 2014;26(3):154–61. doi:10.1111/jerd.12068 

8. Funato A, Salama MA, Ishikawa T, et al. Timing, positioning, and sequential staging in esthetic implant therapy: a four-dimensional perspective. Int J Periodontics Restorative Dent. 2007;27(4):313–23. 

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13. Kan JY, Rungcharassaeng K, Morimoto T, et al. Facial gingival tissue stability after connective tissue graft with single immediate tooth replacement in the esthetic zone: consecutive case report. J Oral Maxillofac Surg. 2009;67(11 Suppl):40–8. doi:10.1016/j.joms.2009.07.004 

14. Kois JC, Kan JY. Predictable peri-implant gingival aesthetics: surgical and prosthodontic rationales. Pract Proced Aesthet Dent. 2001;13(9):691–8. 

15. Wu T, Liao W, Dai N, et al. Design of a custom angled abutment for dental implants using computer-aided design and nonlinear finite element analysis. J Biomech. 2010;43(10):1941–6. doi:10.1016/j.jbiomech.2010.03.017 

16. Lazzara RJ. Managing the soft tissue margin: the key to implant aesthetics. Pract Periodontics Aesthet Dent. 1993;5(5):81–8.  

17. Shor A, Schuler R, Goto Y. Indirect implant-supported fixed provisional restoration in the esthetic zone: fabrication technique and treatment workflow. J Esthet Restor Dent. 2008;20(2):82-95. doi:10.1111/j.1708-8240.2008.00156.x

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19. Shafie HR. Clinical and Laboratory Manual of Dental Implant Abutment. Wiley-Blackwell; 2014. 

20. Kansu G, Gökdeniz B. Effects of different surface-treatment methods on the bond strengths of resin cements to full-ceramic systems. J Dent Sci. 2011;6(3):134–9. doi:10.1016/j.jds.2011.05.002

ABOUT THE AUTHORS

Dr. Emam attended Ain Shams University in Cairo, Egypt, where she received a bachelor’s degree in dentistry as well as an MSc degree and a PhD in fixed prosthodontics. In 2021, she was a postdoctoral visitor researcher at the University of Bonn in Germany. Later, she received a professional diploma in hospital infection control from the Faculty of Medicine, Ain Shams University. She is currently a lecturer in the department of fixed prosthodontics, Faculty of Dentistry, Ain Shams University, and has authored several publications in the field of prosthodontics. She is also a speaker at national and international dental conferences. She can be reached via email at marwaemam@asfd.asu.edu.eg.

Marwa Emam, MSc, PhD

Dr. Eldimeery attended Ain Shams University, where he received a bachelor’s degree in dentistry as well as an MSc degree and a PhD in fixed prosthodontics. He is the owner of Perfect Dental Clinic private practice and course coordinator of the postgraduate occlusion program, Faculty of Dentistry, Misr International University, in Cairo, Egypt. He is also a speaker at national and international dental conferences. He can be reached via email at aymangalal@asfd.asu.edu.eg.

Ayman Eldimeery, MSc, PhD

Disclosure: The authors report no disclosures.

Over the past 30 years, the approach to replacing a missing tooth or a couple of missing teeth has changed dramatically. Implant dentistry has almost become the standard of care for single- or multiple-tooth replacement due to the assumption that it is a less invasive and more durable approach than a fixed prosthesis. Traditional crown-supported fixed prostheses require aggressive tooth removal because they need taper and parallelism between both abutments. For many tooth-conserving clinicians and patients, the idea of cutting adjacent teeth for a fixed bridge is unimaginable considering the collateral damage and possible side effects. Most patients deem a fixed implant to be more desirable than a removable partial denture.

After 30 years of dental implants, astute dental professionals have learned that, in many cases, dental implants are neither more minimally invasive nor problem-free. In a large study of the Swedish population, it was found that at 9 years, 45% of all patients presented with peri-implantitis, bleeding on probing/suppuration, and bone loss greater than 0.5 mm, as well as a 7.6% implant loss during the same period.^1,2 

In some cases, the patient has to undergo invasive bone augmentation graft surgeries to place a dental implant. The procedure is far from minimally invasive or problem-free, especially when considering that 11.3% of implants placed on grafted sites fail during the first 5 years of function.³ Also worthy of note is that placing dental implants in young patients may result in long-term “aesthetic failure,” meaning successful integration but unaesthetic positioning due to the development of the alveolar process. When considering the many possible complications of implant tooth replacement and the advances in adhesion and dental materials, it may be time for astute professionals to consider minimally invasive bonded bridges as a first-choice option in certain clinical circumstances. 

THE EVOLUTION OF MINIMALLY INVASIVE ANTERIOR BONDED BRIDGES

When thinking about bonded bridges, many clinicians think of the Maryland bridge,⁴ which is broadly viewed as unsuccessful. A common and very problematic complication with the metal 2-retainer design is the debonding of one retainer, often resulting in secondary caries. This complication can be caused by the lack of sufficient adhesion to the metal pad and the flexibility of thin metal abutment wings, which causes a peeling effect. Also, occlusal forces have consequences on anterior teeth, creating an uneven tooth deflection. All of the above problems combined lead to increased failure rates. Subsequently, Yamashita and Yamami⁵ introduced a new design in Japan, adding mechanical retentive features to the “adhesion bridge” and utilizing a metal adhesive. Figures 1 to 4 show a bonded bridge treated by Dr. Bertolotti, successfully using this concept on a cantilever bridge made more than 30 years ago and still in service. 

Figure 1. Preoperative view of a very young patient with a congenitally missing lateral.

Figure 2. Occlusal view of the retainer wind design, showing the channel preparation on the mesial of the canine.

Figure 3. The cast with the nickel-chromium-based alloy, Rexillium III, for rigidity and a PFM pontic.

Figure 4. The bridge was bonded with Opaque shade PANAVIA 21 (Kuraray Noritake Dental).

THE CANTILEVER BONDED ZIRCONIA BRIDGE

In 1990, all-ceramic adhesion bridges began to be used. Realizing the disadvantages of the 2-retainer design for anterior teeth, Kern⁶ introduced the single-retainer (cantilever) design using all-ceramic materials with excellent success. Alumina bridges had high adhesive success but with higher fracture rates than desirable. Kern subsequently began using zirconia to replace the alumina and established successful methods for bonding to zirconia, a non-etchable ceramic. The survival rates reported were remarkably high: 99.2% at 10 years. Fracture of the zirconia was rare, but “debonds” did occur. Generally, the debonded bridges were successfully rebonded. The rare, fractured zirconia bridges were traced to poor design in the stressed connector areas, and subsequently, minimum design requirements were established for clinical success: a minimum connector height of 3 mm and connector thicknesses of 2 mm, minimum lingual pad thicknesses of 0.7 mm, and a minimum bonding area of 30 mm² on the retainer. Figure 5 depicts an ideal preparation following the above guidelines.⁶ Using the single-retainer zirconia concept, a patient with a missing left lateral incisor received a zirconia bonded bridge with a single canine retainer (Figures 6 to 8). 

Figure 5. Kern-style lingual retained wing preparation. (Image courtesy of Dr. Mathias Kern and Quintessence Publishing.)

Figure 6. Patient with missing lateral. (Image courtesy of Dr. Charles Ruefenacht.)

Figure 7. Lingual view of a zirconia cantilever bridge. (Image courtesy of Dr. Ruefenacht.)

Figure 8. Facial view of the previous case. (Image courtesy of Dr. Ruefenacht.)

ALTERNATIVE DESIGNS FOR ANTERIOR BONDED BRIDGES

Understanding principles learned through the evolution of bonded bridges allows us to be more creative with different designs based on the variety of clinical circumstances our patients present. The 6 primary considerations for success are materials selection, sufficient dimension of connectors, sufficient stiffness on the bonded retainer pad, sufficient size of the bondable surface, proper bonding protocol, and proper management of occlusal forces. An example of a variation required by clinical circumstances would be when a patient is treatment-planned for porcelain veneers for aesthetic reasons and there is a missing tooth. An important variation on the retainer design frequently used by Dr. Ruiz is the porcelain veneer-supported bonded bridge with 2 retainer wings. When the bonded bridge is being placed where severe occlusal forces are expected, a 2-retainer option should be considered. Tagami et al⁷ showed that a 2-retainer option withstands higher debonding forces than a single retainer on posterior bonded zirconia bridges, with narrow- and wide-rest designs showing no statistical difference in retention. Other clinical circumstances possibly requiring 2 retainers could include canine and first premolar replacements, where anterior and posterior teeth are connected, especially on heavy grinders. Figures 9 to 11 depict a case using an anterior veneer to posterior onlay-proximal rest-retainer design.

Figure 9. Canine replacement using an anterior veneer to posterior proximal-facial rest-retainer design.

Figure 10. Wax design of a bonded bridge.

Figure 11. Immediately after bonded cementation.

POSTERIOR MINIMALLY INVASIVE BONDED BRIDGES

While the adhesive forces can retain properly designed cantilevered posterior bridges, Passia et al⁸ have shown short-term clinical durability with cantilever posterior bonded bridges. Long-term experience has shown that posterior teeth with cantilevers often cannot withstand occlusal forces successfully, especially in bruxers; those teeth frequently show signs of occlusal trauma and even fractures (Figures 12 and 13). A posterior 2-retainer design could be considered a safer option because the occlusal forces will be better supported, and with a preparation mostly on enamel, it can still be considered extremely minimally invasive. Design can vary dramatically depending on the condition of existing retainer teeth. One common scenario is the 2-inlay/onlay retainer design, especially when retainer teeth already have existing restorations. Figure 14 shows a molar rest-retainer extending facially for aesthetic purposes. The features in this preparation are sufficient bonding surface to exceed 30 mm² minimum, a 1-mm proximal-occlusal reduction, and needing to maintain parallelism to the second retainer tooth. This preparation is primarily on enamel and margins and always supragingival. The posterior connector size should be 3 mm in height and 4 to 5 mm in width. Figures 15 and 16 show a posterior 2-retainer bonded bridge using the above design. While the profession has limited experience with minimally invasive posterior bonded bridges, they are a very desirable option because of their minimally invasive nature. The authors’ extensive experience in adhesive dentistry gives them the confidence to know that a properly designed and bonded adhesive bridge retainer will have equal or fewer chances of coming loose than a crown-retained counterpart with traditional crown and bridge cement. Attention to lateral forces and understanding the Three Golden Rules of Occlusion⁹ will yield more manageable forces to the fixed prosthesis. 

Figure 12. Before and after photos of a posterior cantilever bridge that caused the full fracture of a retainer tooth.

Figure 13. A second case with a similar clinical circumstance as the previous one.

Figure 14. A molar rest-retainer design.

Figure 15. Zirconia restoration in the cast.

Figure 16. Clinical view immediately after cementation.

ZIRCONIA AND BONDING TO ZIRCONIA

The assumption that all zirconia restorative materials are the same will lead to frustration and failure. Attention should be placed on choosing a properly manufactured, high-strength Y3 (3 mol% yttria) zirconia, like KATANA Zirconia LT, HT, or HTML Plus (Kuraray Noritake Dental). More translucent Y4 (4 mol% yttria) or higher zirconia formulations are weaker and are more likely to lead to fractures of the connector. The elastic modulus of zirconia is superior to precious metal, thus making it a better choice for stiff-bonded retainer pads. Kern et al¹⁰ have shown that 0.7 mm is the sufficient thickness for anterior retainer pads. Posterior rest/pads should be 1 mm. Bonding to zirconia has been tested by long-term studies, allowing clinicians to understand that zirconia adhesion can be very strong and durable.¹⁰ There are multiple ways to successfully bond to zirconia. Blatz et al¹¹ have suggested the APC Concept: A stands for air abrading with aluminum oxide particles; P stands for priming with MDP-based primer (CLEARFIL CERAMIC PRIMER [Kuraray Noritake Dental]); and C stands for cement, using a self-cure or dual-cure resin cement, like Panavia V5. Alternately, Dr. Bertolotti has advocated for more than a decade for a simple and proven method to bond to zirconia: alumina sand blast and air remove the powder, (do not rinse with water, as it slightly decreases adhesion), followed immediately by the application of Panavia F 2.0 or 21 (Kuraray Noritake Dental) (both MDP-containing resin cements do not require primer) and seating on phosphoric-etched enamel.

CONCLUSION 

After almost 40 years of experience with osseointegrated implants for tooth replacement, it is evident that they are not trouble-free nor minimally invasive in many cases. After more than 30 years of trial and experience, adhesion bridges have evolved. They are highly successful treatment options for anterior teeth and, in many cases, should be considered a first-choice treatment over more invasive implant procedures. Their use for posterior missing teeth is now being established with some very promising early results. As always, the clinician is responsible for making a proper case selection, discussing the pros and cons of each procedure, and allowing the patient to make an appropriate, informed decision. Most bridges are currently being made of Y3 zirconia and minimally invasive tooth preparations in enamel.  

REFERENCES

1. Derks J, Schaller D, Håkansson J, et al. Effectiveness of implant therapy analyzed in a Swedish population: prevalence of peri-implantitis. J Dent Res. 2016;95(1):43–9. doi:10.1177/0022034515608832

2. Derks J, Håkansson J, Wennström JL, et al. Effectiveness of implant therapy analyzed in a Swedish population: early and late implant loss. J Dent Res. 2015;94(3 Suppl):44S-51S. doi:10.1177/0022034514563077

3. Eckert SE, Salinas TJ, Akça K. Chapter 6: Implant fractures: etiology, prevention, and treatment. In: Froum SJ, ed. Dental Implant Complications: Etiology, Prevention, and Treatment. 2nd ed. Wiley-Blackwell; 2015: 132–44.  

4. Thompson VP, Del Castillo E, Livaditis GJ. Resin-bonded retainers. Part I: Resin bond to electrolytically etched nonprecious alloys. J Prosthet Dent. 1983;50(6):771–9. doi:10.1016/0022-3913(83)90088-4 

5. Yamashita A, Yamami T. Design and clinical procedures of adhesion bridge (adhesion splint). J Jap Pros Soc. 1982; 26:592–8.

6. Kern M. Resin-Bonded Fixed Dental Prostheses: Minimally invasive – esthetic – reliable. 1st ed. Quintessence Publishing; 2018. 

7. Tagami A, Chaar MS, Zhang W, et al. Retention durability of one-retainer versus two-retainer posterior RBFDPs after chewing simulation. J Mech Behav Biomed Mater. 2022;133:105353. doi:10.1016/j.jmbbm.2022.105353 

8. Passia N, Chaar MS, Kern M. Clinical outcome of posterior cantilever resin-bonded fixed dental prostheses using two different luting agents. J Prosthodont Res. 2022. doi:10.2186/jpr.JPR_D_22_00033 

9. Ruiz JL. The three golden rules of occlusion. Dent Today. 2010;29(10):92–3. 

10. Kern M, Passia N, Sasse M, et al. Ten-year outcome of zirconia ceramic cantilever resin-bonded fixed dental prostheses and the influence of the reasons for missing incisors. J Dent. 2017;65:51–5. doi:10.1016/j.jdent.2017.07.003

11. Blatz MB, Alvarez M, Sawyer K, et al. How to bond zirconia: The APC concept. Compend Contin Educ Dent. 2016;37(9):611–7. 

ABOUT THE AUTHORS

Dr. Ruiz is founder of the Los Angeles Institute of Clinical Dentistry, former course director of the University of Southern California’s Esthetic Dentistry Continuum, associate instructor at Gordon J. Christensen Practical Clinical Courses in Utah, and an independent evaluator for Clinicians Report. He is the author of Supra-Gingival Minimally Invasive Dentistry with Dr. Ray Bertolotti and of many research and clinical articles. He has been named as one of Dentistry Today’s Leaders in CE since 2006. He is also in private practice in the Studio District of Los Angeles. He can be reached at drruiz@drruiz.com.

Disclosure: Dr. Ruiz reports no disclosures.

Dr. Bertolotti received his DDS degree from the University of California, San Francisco, after working as a PhD metallurgical and ceramic engineer at Sandia National Laboratories. He is perhaps best known for introducing “total etch” to North America in 1984. He also introduced Panavia in 1985, tin plating in 1989, self-etching primers in 1992, and HealOzone in 2004. He is the founder of Danville Materials (now part of Zest Dental Solutions) and was director of research at the company. The sectional Contact Matrix System, MicroPrime B, MicroEtcher sandblasting, and intraoral tin plating are also his developments. He is a well-known international lecturer, having presented at invited lectures in more than 30 countries. He can be reached via email at rbertolott@aol.com.

Disclosure: Dr. Bertolotti reports no disclosures.

Implants are already recognized as essential to enhancing a patient’s quality of life. To ensure successful integration of the oral implant in the patient’s edentulous area, implants are now being developed in all different sizes, shapes, and widths, with various grooved surfaces and designs. This facilitates prosthetic restoration and the return of function. However, to achieve successful implant integration, aesthetic enhancement must be considered as an added possibility, along with phonetic improvement, when needed.

The practitioner’s goal is for a patient to be able to enjoy improved mastication as well as to speak with confidence. The patient is not only able to avoid a denture, which would hinder speaking and masticatory functions, but after successful oral implant integration, the patient also has a more youthful appearance and the potential for a new outlook on life. 

The success of oral implants depends on the acceptance of the implant and its integration with the bone. Certain considerations of the implant surgical site must first be made. Key questions include whether the bone of the implant surgical site can be optimized to ensure predictable integration and whether there is enough bone to support an implant. Another important question is whether there is enough bone to support and ensure predictable integration. Extractions are a major concern today.

After extraction, will there be enough bone to support the endosseous implant and its prosthetic restoration? Currently, it is generally accepted and advised to extract sooner rather than later as there is more bone available to support an implant. By waiting too long to extract, you risk ending up with less than the desired amount of bone. The more bone that is available, the more the implant surface contacts bone and, with all of today’s designs, the more predictable the osseous integration and success are.

This article emphasizes the preservation of the osseous walls of the extraction site during surgical extraction. There are now new proper surgical instruments with which the practitioner can, without strain or unnecessary physiologic positions, access and luxate in mesial and distal directions and remove the roots while preserving both the buccal and lingual walls of the osseous socket. This enables the retention of the existing blood supply, which will guide and aid the osseous regeneration of the future ideal osseous implant site.

In the history of dental extractions, removing the debilitated tooth out of the oral cavity as rapidly and as painlessly as possible has always been paramount. Based on the concept that the buccal bone is usually the thinnest zone of bone that retains the tooth and that it provides the least resistance, it is common practice after anesthesia to luxate in a bucco-lingual movement. Anatomically, the buccal plate of bone is usually much thinner than the palatal or lingual osseous plates.

However, this article will show that this method will not meet with optimal success. The easier extraction toward the buccal will actually result in the loss of more buccal bone. This is because healing depends on the available blood supply, primarily from the osseous walls of the extraction site. The constant pressure from the buccal-lingual luxation leads to ischemia in the remaining thin plate of buccal bone. The ischemia leads to further resorption and, therefore, the loss of buccal bone.

Upon healing, the area will have a depression in the buccal plate and occlusal resorption.

Problems resulting from the healed buccal depression include a buccal void, leading to poor oral hygiene, food retention, and an unaesthetic appearance. Another possible problematic result is the incorrect placement of the implant. The implant needs to be placed in adequate osseous support to succeed.

Since the implant must be placed where bone is, the implant placement will be lingual to the original tooth being replaced. This may result in a situation requiring a prosthesis that is similar to a buccal cantilever—ie, a prosthesis that is overextended buccally to ensure correct occlusion—but this would put undue stress on the implant. During extraction, our goal should be to preserve as much bone as possible by averting bone loss, especially of the buccal osseous plate. 

Mesial-distal Hoexter Luxators have been developed for use during extractions for the specific purpose of preserving as much bone as possible and have been utilized for many years. The Hoexter Luxators, distributed by Hu-Friedy, (Figure 1), are designed to be used expressly in a mesial-distal motion to avoid any buccal pressure. The design of the instruments ensures that the practitioner maintains the correct angle of mesial or distal pressure on the root to be extracted with strain-free access and visibility, thus ensuring a successful and predictable result.

Figure 1. The Hoexter Luxator series of instru- ments is designed to facilitate the removal of roots by mesial-distal movement, allowing the preservation of buccal and lingual osseous walls during an extraction while also allowing the practitioner to visualize the operating area in comfort and ease. The instruments are available in incised edges of 3 or 5 mm for various sized teeth and comfortable angulations.

The Hoexter Luxator technique relies on the concept that it is easier to extract a single-root tooth than a multi-rooted one. After applying local anesthesia, the practitioner should remove the posterior tooth’s crown horizontally at its CEJ, thereby exposing the individual roots. At this time, the Hoexter Luxator should be placed in the desired location (Figure 2) and moved with slight pressure in a mesial-distal direction. The root will become quite mobile and is easily removed.

Figure 2. (a) The Hoexter Luxator in the septal area of the mandibular molar. The force is being directed toward the mesial. (b) The Hoexter Luxator placed at the distal of the mandibular molar with the force directed in a mesial direction. (c) The Hoexter Luxator placed at the mesial of the mandibular molar. The force is being directed in a distal direction. With the constant mesial-distal pressure, the root is easily made mobile and removed, thus preserving the buccal and lingual osseous walls.

There should be no pressure exerted on the buccal plate of bone during the technique. The resultant void will have its osseous walls intact. This can and will induce osseous regeneration and result in the desired healthy osseous support for the soon-to-be-inserted implant. This regenerated bone will include the buccal wall as well as the mesial, distal, and lingual and probably some interseptal bone. All the remaining osseous walls may be productive in guiding the positive regeneration of bone.

By using this technique and the Hoexter Luxator instruments, you will avoid the unhygienic buccal void; the unaesthetic, dark appearance of the buccal depression; and the resorptive depression of the buccal bone. You will also avoid the placement of an implant too lingually, which may cause future occlusal trauma. By successfully completing these steps with the Hoexter Luxator instruments, you will help to avoid bad oral hygiene and to overcome aesthetic and restorative challenges, thereby avoiding future occlusal trauma. 

CASE PRESENTATION

Figures 3 to 8 demonstrate how a practitioner can remove roots while preserving both the buccal and lingual walls of the osseous socket. 

Figure 3. Tooth No. 31 (LR second molar) with the temporary crown off, showing caries and broken tooth structure.

Figure 4. Tooth No. 30 with its temporary crown now off, exposing extensive caries, poor remaining tooth structure, and poor prognosis for both teeth Nos. 30 and 31.

Figure 5. Tooth No. 30 crown portion divided into 2 halves.

Figure 6. All 4 root sockets and even the osseous septum of tooth No. 30 were preserved by luxating mesial-distally.

Figure 7. All 4 of the roots were easily luxated out.

Figure 8. Blood clots seen in the No. 30 and 31 sockets.

After the extraction, I recommend the utilization of guided bone regeneration (GBR). After the removal of the individual roots with the mesial-distal luxation described, leaving the intact osseous walls where the removed roots were, I strongly advise you to use an osseous regenerative bone graft material (Figures 9 and 10) to fill the described void. Following the bone graft, I place a covering of an absorbable barrier. It is sutured, covering the void-filled osseous graft as a GBR technique. 

Figure 9. Osseous graft material was inserted into the sockets of both Nos. 30 and 31.

Figure 10. An absorbable membrane was placed over the grafts, such as in a GBR technique, before suturing.

After the correct time for healing (Figure 11), bone regeneration will result in a supported endosseous implant being placed in its correct position (Figures 12 and 13).

Figure 11. The lower right healed area at 3 months postoperatively.

Figure 12. Exposed regenerated bone area 3 months later. Note the full ridge of bone regenerated buccal-lingually as well as mesial-distally.

Figure 13. Implants inserted at bone level in the No. 30 and 31 positions.

The practitioner at the proper time will then be able to provide the optimal prosthetic replacement—a physiological one—in occlusal harmony: one that is physiologically shaped for the best function as well as aesthetically pleasing and easy to maintain. 

The required period of time is allowed for the bone to mature and allowing osseous integration with the implant (Figures 14 and 15).

Figure 14. Implant healing abutments in place.

Figure 15. The keratinized area of the mucogingival flap was sutured at the correct level.

Changing the temporary healing abutment to a permanent abutment is sequential. This author prefers the utilization of a custom-made abutment, followed by an aesthetically pleasing, occlusally and physiologically functioning prosthesis (Figures 16 and 17). The surrounding keratinized gingival tissue will allow the patient to maintain his or her oral hygiene with more ease, thus allowing predictability of maintaining this desired result.

Figure 16. Buccal view of the completed, restored prosthesis with healthy keratinized tissue.

Figure 17. Lingual view of the restored prosthesis with healthy keratinized tissue.

ABOUT THE AUTHOR

Dr. Hoexter received his DMD degree from Tufts University in Boston. He is director of the International Academy for Dental Facial Aesthetics and a Diplomate of Implantology in the International Congress of Oral Implantologists and the American Society of Osseointegration. He is a Diplomate of Dental Aesthetics from the American Board of Aesthetic Dentistry. He has been awarded 13 Fellowships and practiced in New York City, limited to periodontics, implantology, and cosmetic periodontal surgery.

He is also a clinical professor in the periodontal and implant department at Temple University in Philadelphia. He was previously a clinical professor in periodontics at the University of Pittsburgh. Dr. Hoexter lectures throughout the world and has been published extensively both nationally and internationally. He can be reached at drdavidlh@gmail.com.

Disclosure: Dr. Hoexter has a financial arrangement with Hu-Friedy, the manufacturer and distributor of Hoexter Luxators.

Guided surgical procedures allow the practitioner to diagnose and treatment plan dental implant positioning. Being able to visualize the final process prior to any surgical intervention is an art that is accelerated with virtual design. CBCT and software analysis provides a 3D image of the edentulous space that requires a dental implant. Digital positioning helps minimize the fear of damaging vital anatomy, such as the mandibular or mental nerves, and aids in proper angulation in the available hard tissue to maximize the emergence profile and smile design of the final prosthesis. Taking a tooth-down approach to surgical implant placement helps to idealize the final prosthetic design to a high level.

CBCT analysis and subsequent surgical guide fabrication are an outstanding means to a functional and aesthetic end. However, surgical guides are only as accurate as the fabrication process, and any discrepancy or error in fabrication could lead to malposition and possible trauma.

That being said, when the proper high-quality CBCT analysis is done and the surgical guide is both tooth- and hard-tissue-supported, the surgical placement of the implant is precise. It should provide for an outstanding long-term prognosis.

Here we demonstrate the CBCT analysis and fabrication of a tooth-borne surgical guide for the placement of a single dental implant in the edentulous mandibular left first molar to help provide a patient with increased chewing efficiency and function. This single dental implant crown will eliminate the need for the conventional removable partial denture that has been worn. The patient’s quality of life is thus improved.

Several important indications need to be considered before treatment planning any dental implant reconstruction, whether it be a single tooth; multiple teeth; support for a removable, implant-retained palateless overdenture or partial denture; or a fixed full-arch, implant-retained prosthesis.

There are several conditions that must be evaluated. First, the patient’s overall health should be considered. Any healing problems or uncontrolled medical conditions, such as uncontrolled diabetes or immunosuppressive diseases, could affect the integration of the implant.^1,2 Medication use, such as bisphosphonates, could inhibit proper healing of bone around the implant.³ Bleeding conditions may be a contraindication to surgical intervention.² The quantity and quality of available hard tissue must be considered.

There must be adequate vertical and horizontal bone to support the fixture. This means that there should be considerable width to allow at least 1 to 2 mm of facial and lingual cortical bone and enough height to provide an implant that can support an implant crown with at least a 1:1 crown/root ratio.⁴ The posterior mandible presents some unique complications to both the experienced and unexperienced practitioner. As teeth are lost, the residual ridge will physiologically shrink in 2 dimensions: apically and lingually.

Thus, the implant may not necessarily be placed where the tooth structure was originally; rather, it will be positioned more lingually.⁵ This must be examined and communicated to the patient because the final crown may feel “thicker” to the patient on the lingual aspect. It is best to discuss the final design with our patients prior to beginning the process. Our patients, however, often present with much information gathered from their internet searches on the benefits of implant dentistry.

Risks need to be explained in detail, especially in compromised circumstances. The maxillary posterior region also provides some complications as teeth are lost. Not only does the residual ridge shrink palatally and apically, but the sinus floor may collapse as the tooth root structure no longer supports it.⁶

CASE REPORT

CBCT analysis allows the practitioner to evaluate the anatomic restrictions to a high level. Virtual placement and crown fabrication was completed and discussed with the patient (coDiagnostiX [Dental Wings]). Figure 1 illustrates the amount of vertical and horizontal bone loss the patient exhibited, as well as the super-eruption of the opposing dentition. After anatomic and financial considerations were discussed, the patient elected to have a single implant crown placed to improve chewing ability and eliminate the removable appliance he or she had been wearing for years. Epithelial attachment should also be considered here, as there must be an adequate band of attached gingiva on the facial aspect of any dental implant.

As teeth are lost and bone shrinkage occurs, the mucosal tissue often migrates to the facial aspect of the edentulous ridge.^7,8 This concept will be reintroduced shortly. Figure 2 demonstrates the sagittal view of available bone in the mandibular first molar site. Minimal hard-tissue availability and the proximity to the mental foramen and mandibular nerve made this a good situation to consider a guided surgical procedure (PaX-i3D Green [Vatech America]).

The implant could be virtually positioned in the available bone, and the final implant-screw-retained crown could be visualized. The access hole for this crown would necessarily be on the lingual aspect of the occlusal surface due to the lingual positioning of the fixture itself. With the information presented via the CBCT scan and accurate study casts, 3D Diagnostix (3DDX) was able to fabricate a stable tooth and a hard-tissue-supported surgical guide to aid my surgical angulation and depth positioning of a 4.3-mm × 10-mm Hahn Tapered Implant System (Glidewell) (Figure 3). The access hole in the surgical guide allowed me to use the Hahn Tapered Implant Guides Surgical Kit protocol during placement.

There are no keys in this system, instead, there are burs that accommodate for the implant itself, soft tissue, and thickness of the guide. This particular system is simple to use and mimics the conventional Hahn surgical protocol. Many of our surgical guides were tissue-supported in the past, which resulted in potential errors in seating. Today, most guides are hard-tissue-supported, which requires a reflection of the tissue to be made so that the acrylic sits directly on the available bone structure.⁵

Figure 4 illustrates a full-thickness incision on the crestal aspect of the residual ridge in the attempt to save the available attached gingiva.

The osteotomy was made directly through the surgical guide. Each osteotomy bur has a stop on it, so keys are no longer required. This concept provides for accurate location. Once the site was prepared, the implant was ratcheted to position, again to the preset hub of the delivery insertion (Figure 5).

The 4.3-mm-diameter Hahn Tapered Implant System was torqued in the site that was virtually determined by our CBCT analysis and planning software. The Hahn Tapered Implant System has an aggressive thread design and a 1-mm machined collar. A cover screw was hand tightened into the implant, and the tissue was sutured with Vicryl PGA (Newport Biologics) (Figure 6). You can see that the incision line was lingual, but the implant was placed in the available bone.

Following 3 months of integration, the edentulous ridge was healed and ready for the next steps. The implant needed to be exposed to remove the cover screw to thread in an impression coping. Using the surgical guide, an indelible marker indicated the precise implant position.

A tissue punch (Salvin Dental Specialties) was used to remove the tissue above the implant (Figure 7). A Hahn Tapered Implant System impression post was threaded into the implant, and a radiograph was taken to ensure complete seating of the metal-to-metal components (Figure 8).

It is critical to realize that there must be keratinized tissue on the facial aspect of all our dental implants.

Failure to realize this may result in periodontal issues and potential implant failure.

This is where complications may arise. It is clear in Figure 8 that there was no band of attached gingiva on the facial aspect of the impression coping. This would become a problem if not addressed. Even though the impression was made using polyvinylsiloxane medium- and heavy-body material (Kettenbach LP), I decided to do a tissue-repositioning reflection. Again, I made my incision lingual to the crest of the ridge in the hopes of harvesting at least 2 mm of attached gingiva.

This attached epithelium would then be replaced to the facial aspect of the implant. To do this, a 5-mm-tall healing abutment was torqued to 25 Ncm (Figure 9). A periodontal repositioning technique was used. Figure 10 demonstrates the suturing technique used to reposition the attached gingiva to obtain a healthy band on the facial aspect. The reverse cutting one-half round needle engaged the mesial-facial aspect of the repositioned flap. The suture was then wrapped around the tall healing abutment, not engaging the lingual tissue whatsoever.

The needle was then reversed and engaged the distal-facial aspect. The suture wrapped around the healing abutment again, and a knot was made on the mesial. This took the band of attached gingiva that was originally on the lingual aspect of the crest and moved it to the facial aspect of the implant itself. One suture provided this. The exposed hard tissue would granulate in at a rate of 0.5 to 1 mm per day and require no special care.^9-12 There was minimal postoperative discomfort for the patient with this procedure.

In 3 weeks, the implant-retained crown was ready for seating. The tall healing abutment was removed, exposing a healthy cuff of attached gingiva (Figure 11). The final screw-retained BruxZir zirconia crown (Glidewell) was torqued to 35 Ncm using a seating jig to stabilize the crown during torqueing of the abutment screw. The access hole was covered over with a composite restoration (Figure 12). The periodontal health of the implant was maintained. The screw-retained prosthesis eliminated the need for cement to retain the crown.

The patient was provided with a tooth to help in chewing function.

The final digital radiograph illustrates a complete seating of the crown significantly away from being disturbed and vital anatomy (Figure 13). 

Differences exist between the tissue around natural teeth and dental implants. A junctional epithelium serves as the attachment of the implant to the oral mucosa. Natural teeth have a connective tissue attachment apically that is not apparent around dental implants.^13,14

The oblique and parallel fibers around dental implants are not connected, and thus there is no periodontal ligament present. Since there is no vascular attachment, bacterial invasion is possible; thus, a firm band of attached gingiva on the facial aspect of the implant is critical to a healthy periodontal state.^7,8 Without a keratinized band, there is a potential for inflammation with improper plaque control. This can affect the implant as the inflammation eventually extends apically around the implant body itself.

The literature indicates that a minimum band of at least 2.0 mm of keratinized tissue around an implant will help reduce inflammation and trauma caused by brushing.⁷ The best way to determine the availability of attached gingiva is to infiltrate the surgical site prior to surgical intervention.

The anesthetic fluid will lift the mucosal tissue, and the mucogingival line will become apparent. 

CONCLUSION

Dental implants have been proven to be an outstanding alternative to conventional removable appliances in creating function and aesthetics for our patients.^15,16 Having fixed prostheses eliminates the need to remove the appliances and improves the patient’s psychological quality of life. Taking a tooth-down approach to diagnosing and treatment planning any dental implant will help to communicate to the patient the final result and also help the dentist design an implant-retained prosthesis with an excellent long-term prognosis.

Vital anatomy needs to be clearly understood. With the advent of CBCT analysis and virtual placement of our dental implants and the evaluation of crown design using planning software, the practitioner can visualize the entire case finished before ever starting. The possibility of surgical placement can be seen preoperatively, and the dentist may determine if the case is within his or her wheelhouse or if other options should be considered. The positions of the mandibular and mental nerves, as well as the maxillary sinuses, are a concern.

Modern technology allows us to be able to view vital anatomy precisely. Although bone morphology is easily visualized, one common error made is not recognizing the lack of attached gingiva on the facial aspect of our surgical sites.

Once recognized, the problem is easily corrected with a simple periodontal technique.

References

1. Hwang D, Wang HL. Medical contraindications to implant therapy: part I: absolute contraindications. Implant Dent. 2006;15(4):353–60. doi:10.1097/01.id.0000247855.75691.03

2. Hwang D, Wang HL. Medical contraindications to implant therapy: part II: relative contraindications. Implant Dent. 2007;16(1):13-23. doi:10.1097/ID.0b013e31803276c8 

3. de-Freitas NR, Lima LB, de-Moura MB, et al. Bisphosphonate treatment and dental implants: A systematic review. Med Oral Patol Oral Cir Bucal. 2016;21(5):e644-51. doi:10.4317/medoral.20920

4. Flanagan D. Osseous remodeling around dental implants. J Oral Implantol. 2019;45(3):239–46. doi:10.1563/aaid-joi-D-18-00130

5. Mandelaris GA, Rosenfeld AL, King SD, et al. Computer-guided implant dentistry for precise implant placement: combining specialized stereolithographically generated drilling guides and surgical implant instrumentation. Int J Periodontics Restorative Dent. 2010;30(3):275–81. 

6. Kern JS, Kern T, Wolfart S, et al. A systematic review and meta-analysis of removable and fixed implant-supported prostheses in edentulous jaws: post-loading implant loss. Clin Oral Implants Res. 2016;27(2):174–95. doi:10.1111/clr.12531

7. Tetè S, Zizzari VL, Borelli B, et al. Proliferation and adhesion capability of human gingival fibroblasts onto zirconia, lithium disilicate and feldspathic veneering ceramic in vitro. Dent Mater J. 2014;33(1):7-15. doi:10.4012/dmj.2013-185 

8. Ashurko IP, Tarasenko SV, Repina SI, et al. Keratinized attached gingiva around dental implants: the role, structure, increasing techniques. IAJPS. 2018;5(10):m10887-10891. doi:10.5281/zenodo.1472779

9. Lindhe J, Berglundh T. The interface between the mucosa and the implant. Periodontol 2000. 1998;17:47-54. doi:10.1111/j.1600-0757.1998.tb00122.x 

10. Schrott AR, Jimenez M, Hwang JW, et al. Five-year evaluation of the influence of keratinized mucosa on peri-implant soft-tissue health and stability around implants supporting full-arch mandibular fixed prostheses. Clin Oral Implants Res. 2009;20(10):1170–7. doi:10.1111/j.1600-0501.2009.01795.x 

11. Berglundh T, Lindhe J, Ericsson I, et al. The soft tissue barrier at implants and teeth. Clin Oral Implants Res. 1991;2(2):81-90. doi:10.1034/j.1600-0501.1991.020206.x 

12. Adibrad M, Shahabuei M, Sahabi M. Significance of the width of keratinized mucosa on the health status of the supporting tissue around implants supporting overdentures. J Oral Implantol. 2009;35(5):232–7. doi:10.1563/AAID-JOI-D-09-00035.1

13. Warrer K, Buser D, Lang NP, et al. Plaque-induced peri-implantitis in the presence or absence of keratinized mucosa. An experimental study in monkeys. Clin Oral Implants Res. 1995;6(3):131-8. doi:10.1034/j.1600-0501.1995.060301.x

14. Kim BS, Kim YK, Yun PY, et al. Evaluation of peri-implant tissue response according to the presence of keratinized mucosa. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;107(3):e24–8. doi:10.1016/j.tripleo.2008.12.010 

15. Oh SH, Kim Y, Park JY, et al. Comparison of fixed implant-supported prostheses, removable implant-supported prostheses, and complete dentures: patient satisfaction and oral health-related quality of life. Clin Oral Implants Res. 2016;27(2):e31–7. doi:10.1111/clr.12514

16. Brennan M, Houston F, O’Sullivan M, et al. Patient satisfaction and oral health-related quality of life outcomes of implant overdentures and fixed complete dentures. Int J Oral Maxillofac Implants. 2010;25(4):791-800. 

ABOUT THE AUTHOR

Dr. Kosinski received his DDS degree from the University of Detroit Mercy School of Dentistry (Detroit Mercy Dental) and his Mastership in Biochemistry from the Wayne State University School of Medicine. He is an affiliated adjunct clinical professor at Detroit Mercy Dental; serves on the editorial review board of REALITY, the information source for aesthetic dentistry; and is the past editor of the Michigan Academy of General Dentistry Update.

He is currently the editor of the AGD journals General Dentistry and AGD Impact and is the editor of Implants Today in Dentistry Today. He is a past president of the Michigan AGD. He is a Diplomate of the American Board of Oral Implantology/Implant Dentistry, the International Congress of Oral Implantologists, and the American Society of Osseointegration. He is a Fellow of the American Academy of Implant Dentistry and received his Mastership in the AGD.

He can be reached at drkosin@aol.com or via the website smilecreator.net.  

Disclosure: Dr. Kosinski reports no disclosures.  

IMPLANT SURFACE DESIGN AND INITIAL STABILITY

Implant stability at placement allows for immediate loading when accepted insertion torque can be achieved. Implants that are pressed (vs threaded) into osteotomies are not able to achieve sufficient insertion torque to allow for immediate loading, whether the surface is coated, treated to roughen it, or has non-threaded surface features such as fins or beads. Additionally, intimate contact of the bone with the entire surface of the implant during placement, allows quicker maturation of the bone at the implant interface.

When a non-threaded implant is placed, a clot lies between the implant surface and the osteotomy on part of the implant surface closer to the implants core, which will require conversion to host bone, delaying the integration period.

Although, Quantum does offer a pressfit finned style implant, the Quantum threaded version offers advantages such as providing immediate stability to permit perfect immediate loading when an acceptable insertion torque level can be achieved. In lower density bone such as found in the maxillary sinus area, when augmentation is to be supplemented at implant placement, it aids in lateral condensation of the bone and initial stability. The potential complications caused by accidental displacement of the implant into the sinus, as can occur with a pressfit finned implant, are greatly minimized or eliminated with the threaded implant design.

The thread geometry of the Quantum implant has deep threads that are spaced to allow for greater initial stability than thread designs that are shallower and more closely spaced. Thread spacing allows for formation of true Harvesian canals between the threads, so circulatory flow in that bone provides for better stability long-term and is easier to maintain under function. Additionally, the deeper threads increase surface area at the bone-implant interface, which combined with the lower surface of the threads being flat, provide high compressive load management of the implant when loaded. (Figure 1)

Figure 1: The thread design of the Quantum threaded implants provides deep engagement of the osteotomy for good initial stability with compressive load distribution when the implant is loaded. Quantum’s osteosupportive thread can also be placed as a pressfit implant.

The implant’s design with a flat apex on all the versions improves compressive loading under function. The self-tapping design aids in placement in dense bone with osseocompression in all bone densities for improved bone quality at the bone-implant interface with better initial stability.

The surface treatment of the implant by the manufacturer has been shown to improve clot contact with the implant at placement and subsequently osteoblasts cell adhesion and the quality of the bone-implant interface. Several surface treatments are available with Quantum implants; resorbable blast media (RBM), hydroxyapatite (HA), and biological titanium interface (BioTi). BioTi is a proprietary acid etch implant surface treatment to provide ideal roughness for enhanced bone-implant interface.

This process involves two rounds of acid etching and passivation to maximize the surface for bone adhesion during integration.

3-IN-ONE ABUTMENT CONNECTION

Quantum has a unique implant platform design allowing 3 different abutment connections on the same implant, expanding prosthetic options during planning or following implant placement. This is available on their Summa, Slim, and Short-T implant lines. Their 3-in-One connection offers a choice of using a Morse taper (TaperLock), a taper abutment with threaded terminal end (TaperLock Thread), or an external hex (Hex). (Figure 2)

Figure 2: Quantum implants offer a 3-in-One abutment connection in the same implant body with a TaperLock (left), TaperLock Thread (middle) and Hex abutment connection (right) on each implant expanding prosthetic options on the same implant when placed.

The Hex connector, when utilized, causes the abutment to engage the sloped (bevel) of the coronal aspect of the implant, acting as a reverse internal hex.

The option of the three abutment connections simplifies abutment selection, so depending on available bone, implant angulation, and type of restoration (fixed, removable, hybrid) – the same implant can be restored. This enables the practitioner to modify the treatment plan during the surgery, or the restorative phase, while using the same implant.

The TaperLock connector utilizes a true Morse 1.5-degree taper connection between the abutment and implant at the platform. This allows a solid abutment head without a screw for a rigid connection, while permitting 360° positioning of an angled abutment head to best position the head for either a cemented implant crown, an overdenture, or a QFit regardless of the angulation of the implant to the desired prosthetic vertical axis.

Once the head is positioned at the correct orientation circumferentially, the head is gently tapped into the implant to frictionally engage the Morse taper connector. When this connector option is selected on the implant, the implant is placed subcrestally, so that when the abutment is inserted, the restorative margin on the abutment is positioned subgingivally.

The solid abutments are available in 0° (straight), 15°, and 25° angulations and different lengths. Abutments are preparable to further customize either the length of the restorative portion of the head, or to aid in paralleling adjacent implants that will connected in a bridge.

The frictional fit between the abutment post and implant connector ensures no microgap providing a hermetic bacterial seal at the connector.

The TaperLock Threaded connector is similar to the TaperLock with a solid abutment head but has a threaded portion at the apical end to allow the practitioner to tighten the abutment to the implant, which provides a rigid connection with extra retention. When this connector option is to be utilized like the TapeLock option, the implant is placed subcrestally. The abutment is provided either as a straight abutment or a custom TaperLock Threaded abutment. This version allows the practitioner to create a custom abutment chairside to accommodate any angulation of the implant in relation to the needed prosthetic axis required. The TaperLock Threaded custom abutment is placed into the implant and tightened prior to any customization. Once secured, the abutment is modified with a carbide bur in a highspeed handpiece, preparing it similarly as a tooth would be prepared for a crown. (Figure 3)

Figure 3: Steps to customize the TaperLock Threaded custom abutment.

The sloping shoulder combined with the diameter of the TaperLock and TaperLock Threaded post at its mergence from the implant provide true platform switching when these options are selected. This allows greater bone thickness in the distance between the crestal level and the widest diameter of the implant, as well as thicker gingival tissue. The greater the bone volume interproximally, the better it can maintain the papilla and bone at its desired level long-term.

This becomes important in narrower situations where either implants need to be placed close to each other, or the implant will be close to an adjacent natural tooth while still providing enough interproximal space for healthy bone and gingival maintenance. The post length between the top of the implant platform and the bottom of the widening of the abutment head is available in two lengths, short (0.5 mm) and long (2.0 mm) for crown and bridge applications.

This permits the implant to be placed at different depths subcrestally and have the restorative margin at the proper level.

The Bevel Hex connector has sloped shoulders below the hex functioning like an internal hex. This unique bevel allows the abutment to engage the crestal portion of the implant, taking stress off the abutment screw, thereby decreasing the potential for screw loosening and stress concentration on the abutment screw that may lead to screw fracture. When this connector option is planned, the implant can be placed subcrestally, crestally, and also can be set coronal to the crestal bone.

CLINICAL SITUATIONS

WHEN SUFFICIENT BONE IS PRESENT IN RIDGE HEIGHT AND WIDTH

Sufficient bone is found in volume with the ridge presenting with adequate height, as well as buccal-lingual width to accommodate in the majority of clinical situations where implants are planned. When that is present, the Quantum Summa and Magnum implants are ideally suited for implant placement. These implants are available in widths of 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 mm with lengths of 8, 9, 11 and 14 mm (depending on the diameter). (Figure  4)

Figure 4: The Quantum Summa implant available in 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0mm diameters and several lengths.

To expand options prosthetically and surgically, the Summa implant incorporates the 3-in-One connector at the platform, which allows modification of placement depth. Deeper placement depth may be utilized when treating the maxilla (Figure 5) or mandible (Figure 6) with the TaperLock or Taper Lock Threaded connection option.

Figure 5: A maxillary canine restored with a Quantum Summa 5 mm x 14 mm implant utilizing the TaperLock Threaded connector after 19 years of function demonstrating bone maintenance and healthy surrounding gingival tissue.

Figure 6: A Quantum Summa 5 mm x 11 mm implant subcrestally placed into site #30 with a healing abutment (left), restored utilizing the TaperLock connector after a 5-years of integration and restoration demonstrating no crestal bone loss (middle and right).

When utilizing the Hex connector option, the implant may be placed with the sloped shoulder at the crestal height or slightly below. (Figure 7)

Figure 7: A 5.0mm x 11mm Quantum Summa implant placed and restored at site 30 utilizing the Hex connector shown 5-years post-restoration with a platform switch prosthetically and maintenance of crestal bone (middle and right).

Quantum allows for good placement stability in addition to ideal immediate placement, immediate fixation, and immediate loading.

INADEQUATE HEIGHT FOR IMPLANT PLACEMENT WITHOUT ADDITIONAL SURGICAL INTERVENTION

Ridge height decreases in an apical direction overtime, following tooth loss, when nothing is present in the ridge at that position. Atrophy of the bone results due to the lack of intraosseous stimulation. In the maxillary posterior, atrophy combined with enlargement of the maxillary sinus (a natural occurrence whether teeth are present or have been lost), creates potential challenges in placing implants in this region without supplemental sinus augmentation procedures to increase bony ridge height. In the mandibular arch, this may present a clinical challenge due to the inferior alveolar nerve (IAN) and what bone height is available crestal to that anatomical structure to accommodate implant placement.

Short implants offer the advantage of allowing placement in decreased crestal height to avoid supplemental surgical procedures. The Quantum Short-T implant was designed in a 6mm height for those clinical situations. (Figure 8)

Figure 8: The Short-T implant available in a 6mm length and 4-6 mm diameters.

The implant is available in diameters from 4.0 to 6.0mm to accommodate various ridge widths present. Utilization in the posterior maxilla allows avoidance of the sinus (Figure 9) and in the posterior mandible avoids infringement on the IAN (Figure 10).

Figure 9: Placement several Short-T implants in the posterior maxilla of 5.0 mm (#13) and 6.0 mm (#14 and 15) width where limited crestal height was available allowing avoidance of sinus augmentation for implant placement.

Figure 10: Quantum Short-T implants in 6.0mm diameter placed to avoid proximity to the IAN, 10 years post treatment.

The Short-T implant is designed, same as the other Quantum implants, with three restorative platform abilities in the same implant, minimizing how many implants are needed to be stocked by the practitioner and allowing modification of surgical placement or prosthetics once the placement is initiated.

When placed so that the implant is flush with the crest, a 6mm depth of available bone is required. If greater height is available (up to 9mm), the Short-T may be placed subcrestal or if less height is present (4-6mm), it may be placed accordingly. (Figure 11)

Figure 11: Various depths the Short-T implant can be placed in bone availability of 6-11mm utilizing the different platform connector options.

The ability to vary crestal depth placement also applies to the Summa and Slim implant lines increasing placement customization at surgery.

When sinus augmentation is indicated along with simultaneous implant placement, a wider Healing Plug is required in this clinical situation to prevent accidental displacement of the implant into the sinus. Utilization of a Morse Taper type connector on the healing abutment requires the abutment to be tapped into the implant and may displace the implant in a superior direction into the sinus. Quantum offers a Healing plug for Short-T, Slim, Summa, and Magnum that utilizes a Taper thread connector with a wide flat head so that healing plug placement does not require to be tapped, thus preventing accidental sinus displacement.

In addition, the flat head allows for soft tissue coverage at surgery. (Figure 12)

Figure 12: The Sinus plug with Taper Threaded connector use allows when the implant is placed with a sinus augmentation to have stability and resist potential movement of the implant into the sinus during the healing and integration period.

NARROW ARCH WIDTH

Limited width of ridge can present in either the mesial-distal or buccal-lingual dimension, related to resorption of the ridge or limited by the space between adjacent teeth. It is not unusual to have a narrow ridge mesial-distally in the maxillary lateral incisor or mandibular incisor positions, as those natural teeth are narrow in dimension that an implant would be replacing. Availability of a two-piece implant for these clinical situations permits the option of delayed loading when insertion torque has too low a value, or another clinical decision indicates that approach, or immediate loading with abutment angle alteration that a single-piece implant in narrow diameter will not permit.

The Slim implant is, as with other Quantum implants, available with three restorative platform abilities in the same implant. This allows the practitioner to place the implant subcrestal or slightly supracrestal and have different restorative options to accommodate various clinical situations.

The implant has a 3.0mm diameter with availability in 9.0, 11.0 and 14.0mm lengths. (Figure 13)

Figure 13: Slim implant is available in a 3.0mm diameter with lengths in 9.0, 11.0 and 14.0mm.

Ideally suited for those narrow clinical situations that are frequently found in the mandibular incisal positions where mesial-distal width may create a clinical challenge. (Figure 14)

Figure 14: A mandibular central incisor requiring extraction (A), placement of a Quantum Slim 3.0 x 11mm 2mm subcrestal achieving 45Ncm of insertion torque allowing for placement of the abutment for immediate load (B), 6-months later the final crown was placed intraorally (C) and a radiograph 30-months post final restoration which confirms maintenance of the crestal bone (D).

HYBRIDS AND OVERDENTURE OPTIONS

Patients may require a hybrid or an overdenture approach for various reasons versus a fixed approach when treating the full arch. Those reasons may be easier home care when the prosthesis can be removed for cleaning by the patient, financial costs being lower for a removable approach, and the patient’s desire for improved denture retention over a fixed approach that may require more implants for a full arch.

An ideal option that can be utilized for either an overdenture or fixed detachable hybrid restoration is the Qfit abutment implant supported system providing a screwless, cementless attachment between the prosthesis and the implants.

When utilized with a fixed approach removal at hygiene, recall appointments is simplified and the patient can be trained to remove it for daily home care.

When extensive ridge resorbtion has occurred, flanges can be extended for esthetic purpose. The prosthetic design also allows elimination of all flanges and is well suited for those clinical situations where minimal ridge resorption has occurred, and maintenance of the residual ridge is desired. The Qfit abutments utilize the TaperLock connection and are available in 0°, 15°, and 25° to allow parallelism. The abutments are provided in short, regular, and long lengths to accommodate implant placement depth and tissue thickness.

The retention coping is processed into the prosthesis either chairside or at the lab and houses an O-ring available in five retention levels. (Figure 15)

Figure 15: Qfit system utilizes a conical retrievable engagement system that can be used for either a fixed or removable hybrid approach that does not require cementation.

A fixed hybrid prosthesis results that can be removed when required. (Figure 16)

Figure 16: Mandibular arch treated with Qfit abutments on 6 implants for a fixed hybrid prosthesis

Should a metal reinforcement substructure be desired the copings can be processed to it then resin or ceramic added to the metal substructure as desired.

O-ring abutments are also available. These are offered in 0°, 15°, and 25° angulations with short, regular, and long post lengths. (Figure 17)

Figure 17: The O-ring abutment is available in three different angulations (0°, 15° and 25°) to allow parallelism of the attachments in the arch.

As this overdenture abutment utilizes the TaperLock connector, it can be rotationally positioned to obtain idea parallelism, then tapped into position to engage the Morse taper connector. The 25° greater angulation than other abutments available permit greater correction of the implants in the arch.

The maxillary anterior can present challenges related to the “triangle of bone,” which results in greater angulations when placing the implant than would be present in other parts of the arch. The Res-Q overdenture abutment system provides an option for treating those clinical situations with an overdenture. (Figure 18)

Figure 18: The Res-Q abutment system with the abutment that engages the TaperLock connection (shown in blue) and the portion that sits in the overdenture (shown in yellow) with the overdenture shown engaged on the implants (right).

A low-profile tissue-level free-standing abutment is a solution for low vertical dimension clinical situations, which can compensate for up to 60° divergence between implants available in 0°, 15°, and 25° angulations. The retention post is processed into the overdenture decreasing the amount of vertical space required and its narrow dimension does not interfere with the dentures buccal flange allowing better esthetics, without the need to bulk out that area (Camel Look) of the overdenture to cover the attachments.

Insertion and removal of the overdenture is easy for the patient and a customizable level of retention is available with 5 different O-rings for a high degree of resiliency and tolerance.

WHEN WIDER MORSE TAPER CONNECTOR IS PREFERRED

Some practitioners may prefer a wider Morse taper connection and in those cases Magnum implants may be preferred.

This implant design has the Threaded fins to achieve stability at insertion and other features of the Quantum implants. It has an internal hex for engagement of the implant driver and a thread below the internal hex for the engagement of the Sinus Healing plug. (Figure 19)

Figure 19: Quantum Magnum implant has a threaded fin design with a Morse taper style connector at the platform and available in several diameters and lengths.

Magnums are available in diameters of 4.5mm, 5.0mm, and 6.0mm, and lengths of 6mm, 8mm, and 11mm.

These implants are designed to be placed subcrestally or crestally, giving the practitioner greater surgical planning based on available bone present. (Figure 20)

Figure 20: A Quantum Magnum implant placed subcrestally at the maxillary premolar shown 3 years post restoration demonstrating maintenance of bone with healthy soft tissue.

CONCLUSION

Utilization of implants to replace missing teeth, whether single units or full arch, can present challenges related to the available bone present and its density. The threaded ‘fins’ on the Quantum implants provide stability at placement that permits immediate fixation and immediate loading compared to non-threaded press-fit finned implants.

This also decreases potential for accidental sinus displacement on insertion.

The unique platform on the 3-in-One connector allows modification on surgical placement, or the prosthetic plan, which increases flexibility during implant treatment.

For further information, please visit www.quantumimplants.com.

ABOUT THE AUTHORS

Dr. Raul Mena

Dr. Raul R. Mena has a number of accomplishments to his name, including: Diplomate American Board of Oral Implantology Implant Dentistry, Medical College of Georgia, School of Dentistry, DMD, Oral, Cranio and Maxillofacial Implantology Hospital Residency, Cedars Hospital, Special Needs Dentistry Hospital Training, GRC Hospital, Bone Anchoring Hearing Aid, Cranio and Maxillofacial Implants Hospital Training, Misericordia Hospital, Chief Dental Technician, Medical College of Georgia, Crown and Bridge Rehabilitation Lab, Co-Director, Maxi-Residency Course, Pittsburgh University, School of Dental Medicine, and President, Quantum BioEngineering, LTD.

Dr. Gary Chike

Dr. Gary E Chike graduated from the Medical College of Georgia with both a Master of Science degree in Medical Illustration, as well as a Doctorate in Dental Medicine. He maintains a full-time private practice in the suburbs of Atlanta, Georgia, and holds an adjunct faculty position at the Dental College of Georgia at Augusta University. 

Dr. Donald Rothenberg

Dr. Rothenberg, a graduate of Tufts University Dental School in 1971, completed a 3 year CE implant program at Harvard School of Dental medicine in 1987. He has been practicing dentistry with a concentration in implantology in Marblehead, Massachusetts since 1971.

Dr. Gregori Kurtzman

Dr. Kurtzman is in private general dental practice in Silver Spring, Maryland, a former Assistant Clinical Professor at University of Maryland in the department of Restorative Dentistry and Endodontics and a former AAID Implant Maxi-Course assistant program director at Howard University College of Dentistry.

He has lectured internationally on the topics of Restorative dentistry, Endodontics and Implant surgery and prosthetics, removable and fixed prosthetics, Periodontics and has over 770 published articles globally, several ebooks and textbook chapters.

Dr. Kurtzman has been honored to be included in the “Top Leaders in Continuing Education” by Dentistry Today annually since 2006. 

He can be reached at dr_kurtzman@maryland-implants.com.

Whether you are currently placing implants free-handed or using a surgical guide, there is certainly a level of inaccuracy built into both of these methods. Freehand (FH) implant placement breeds inaccuracy as the surgeon creates the osteotomy using adjacent and opposing teeth as positioning guides.^1-3 A custom-fabricated surgical guide (a static navigation [SN]), although more accurate, has some degree of play built into the system. Success may be limited by CBCT discrepancies and incorrect placement or instability of the guide. There is definitely more accuracy in tooth-supported guides than in bone- or mucosal-supported ones.⁴ When mucosal-borne, there is a standard deviation (SD) for angulation of the implant of 2.71° as compared to an SD of 9.92° when freehand.³ A surgical guide requires an additional appointment and lab costs as well as intraoral access of all components at the time of surgery. Using a surgical guide, the position of the implant is not alterable during surgery unless the guide is abandoned and FH positioning is used.³ Similar studies have been completed, which also have taken into consideration the platform and apical deviation of positioning. Most notably, the platform deviation for FH placement showed 1.78 +/- 0.77 mm for implant platform and 2.27 +/- 1.02 mm for apical positioning. The DN outperforms the SN by providing approximately 0.5 mm more accuracy on average in angulation of implant placement and 0.15 mm in platform deviation and 0.23 mm in apical positioning precision.¹ Enhanced accuracy decreases the practitioner’s stress and elevates his or her practice’s impression, all while making the surgery visible. This DN system offers precision in one appointment without additional lab fees. Although the SD for DN-placed implants has been found to be similar to that of extremely accurate surgical guides,⁵ for the above-mentioned reasons, DN is more desirable. The drawbacks to the use of DN technology are few. Of course, there is a cost and a learning curve to the system. In addition, few studies discuss the surgical experience of the practitioner with implant placement in general, which should also be considered when assessing implant placement speed, accuracy, and success rates.⁶ Studies report the learning curve to be completed by the 20th surgery.¹ The following case report will discuss the ease of use, precision accuracy, stress reduction, and sophistication of the X-Guide system.

CASE REPORT 

It’s as simple as 1, 2, 3 after choosing your case for implant placement: 

1. CBCT SCAN with fiducials

2. Digital treatment planning

3. Calibration and dynamic navigation

CBCT SCAN With Fiducials 

Our patient presented after 4 months of healing following extraction and bone grafting in the lower left first molar region (Figure 1). A digital intraoral scan of the mouth was obtained (Figure 2). Whether doing same-day surgery or not, the next step includes an innovative bite to be taken using the X-Clip. This X-Clip is a resin bite block lined with a thermoplastic liner that is heated in a water bath to soften it (Figure 3). The X-Clip is then placed in the contralateral side of the implant placement, firmly covering 2 to 3 teeth for 15 seconds. Immediately remove the X-Clip from the mouth and place it in an ice bath for 20 seconds. Reinsert it in the mouth to confirm a solid fit without rock (this step is critical for accurate surgery).

Figure 1. A preoperative lateral view of a 60-year-old’s left mandible prior to implant placement.

Figure 2. An i700 (Medit) intraoral scan was taken for precision digital treatment planning.

For this reason, the X-Clip should not be placed on provisionals or loose teeth unless the primary stability of the clip is achievable. Embedded in the X-Clip are 3 stainless steel trackers, which function as fiducial markers to translate 3 virtual points on the CBCT scan (Figures 4 and 5). The X-Nav technology allows the 3 virtual trackers to merge with the same 3 live trackers to assist in facilitating the surgeon’s digital treatment plan in 3D visualization at the time of surgery. These 3 markers must be rigid and predictably reproduced for accurate results. Place the X-Clip on the patient and take a CBCT scan of the mouth. A bilateral scan is needed to capture the entire X-Clip and implant placement location.  

The X-Guide allows the surgeon to navigate with precise movements of the handpiece in all 3 planes of space for millimeter-by-millimeter accuracy. When all 3 fiducials have green indicators, the system calibration is within 200 μm.⁷ This technology can be delivered the same day, which saves time, energy, and money. This DN is used in many specialties, such as general surgery, neurosurgery, and oncology, with increased accuracy and precision. 

Digital Treatment Planning 

Using appropriate treatment planning software (DTX Studio [Nobel Biocare] was used in this case), and ideally, a restoratively driven mindset, can and should be done only from the crown down, based on prosthetic needs, but also with consideration for the opposing arch for a proper occlusal load. With the advent of angulated screw channel design, ideal implant placement, as well as ideal prosthetics, are obtainable. Intraoral scanning can also be merged at this time for more precision (Figure 6). From the digital plan, provisionalization can be treatment planned and fabricated for placement at the time of surgery, if desired (Figure 7).

Figure 6. An intraoral scan from the i700 was merged with the CT scan and DTX Studio software (Nobel Biocare) to treatment plan from the top down. Ideal tooth placement was generated first, with implant placement following later.

Figure 7. From the digital treatment plan, a model and winged provisional were printed.

Calibration and Dynamic Navigation 

Whether completing same-day surgery or not, calibration of the X-Nav instrumentation should occur prior to seating your patient. Proprietary trackers, which are similar to barcodes, attach to the surgical handpiece and the X-Clip. Calibrating the 2 allows the system to have real-time guidance in 3 dimensions. When using the handpiece, active rays are emitted from a light source and a tracking camera overhead. The drill tip is the third point tracked that is calibrated on a plate that is also barcoded (Figure 8). 

Once the patient is seated, the X-Clip with the Patient Tracker is snapped onto the teeth in the contralateral arch during implant surgery. Touching the drill tip to the Go-Plate calibrates the drill. By touching an adjacent tooth visible on the screen,  the accuracy of the system’s position is confirmed. The camera identified the patterns at all 3 coordinates: the surgical handpiece, the X-Clip arm, and the tip of the drill. The barcodes on the surgical handpiece, the X-Clip arm, and the Go-Plate must be in view of the camera for the system to “go live.” These 3 calibration tools are rechecked between each drill and implant to confirm accuracy in the system.

DN Implant Placement 

Once the above steps are complete, live navigation surgery begins.  Following the bullseye makes precision surgery simple (Figure 9). The bullseye tracks live in 3 dimensions and is visible simultaneously in all 3 dimensions on the screen. The bullseye ring changes color from blue to yellow when the desired osteotomy depth is nearly complete (Figure 10). This GPS-like guided system increases the confidence of the dentist and certainly the patient. The bullseye turns to green when within 0.5 mm of the desired length (Figure 11), then to red, indicating osteotomy depth is achieved (Figure 12). As previously mentioned, maintaining a precise perpendicular angle to the blue crosshairs on the bullseye can achieve precision within 200 μm of the treatment plan. Multiple views are displayed simultaneously for the clinician to monitor the osteotomy depth and drill angle in all planes in order to control every movement with pinpoint accuracy.⁷ Once the proper width and length of the osteotomy are obtained, the same system check steps and live navigation occurs for implant placement (Figure 13). Hand torque confirmation is the final step in implant placement, followed by provisionalization. This case was torqued to 35 Ncm (Figure 14). During the surgical procedure, the surgeon follows the screen while the assistant verifies the intraoral positioning.

This patient was desirous of immediate provisionals. A provisionalization abutment was inserted and assessed for height reduction (Figure 15). The abutment was reduced as needed and manually screwed into place (Figure 16). The provisional was tried into the mouth to ensure appropriate abutment height, and the provisional shell was relined with resin. The author fabricated the provisional with wings to double-check for complete and accurate seating of the provisional (Figure 17). The provisional and abutment were removed from the mouth once the resin reline completely set. Wings were then removed, and access was made through the occlusal from the apical base of the temporary abutment with the access drill provided. The margins were filled in with flowable resin, contoured, and polished to sculpt the tissue during the healing phase as desired (Figure 18).

The provisional was then luted to the temporary abutment, inserted into the implant, and screwed in place via hand torquing. The access was filled with Teflon and composite (Figure 19). The provisional was left out of occlusion and confirmed with articulating paper and shim stock.

The implant would then integrate and be restored in approximately 4 months with a final restoration (Figure 20).

IN SUMMARY  

Recently, advances in implant dentistry have created a greater degree of accuracy through new technology. A shift is occurring from the FH placement of implants and traditional use of surgical guides to more precision with DN implant placement. The X-Nav technology can be easily implemented with current CT scanners and can offer same-day implant placement with precision up to 200 μm. Changes to the plan can be made during the surgical procedure. Live visualization of the oral field is achieved for implant position, angle, and depth at every turn of the handpiece, which offers step-by-step control. DN is as easy as 1, 2, 3, saving the practitioner time, energy, and money while increasing precision and peace of mind in the field of dental implant placement. In the future, robots may be the ones placing the implants!⁸

References 

1. Block MS, Emery RW, Lank K, et al. Implant placement accuracy using dynamic navigation. Int J Oral Maxillofac Implants. 2017;32(1):92-99. doi:10.11607/jomi.5004 

2. Block MS, Emery RW, Cullum DR, et al. Implant placement is more accurate using dynamic navigation. J Oral Maxillofac Surg. 2017l;75(7):1377-1386. doi:10.1016/j.joms.2017.02.026

3. Block MS, Emery RW. Static or dynamic navigation for implant placement–choosing the method of guidance. J Oral Maxillofac Surg. 2016;74(2):269-77. doi:10.1016/j.joms.2015.09.022 

4. Ozan O, Turkyilmaz I, Ersoy AE, et al. Clinical accuracy of 3 different types of computed tomography-derived stereolithographic surgical guides in implant placement. J Oral Maxillofac Surg. 2009;67(2):394-401. doi:10.1016/j.joms.2008.09.033

5. Emery RW, Merritt SA, Lank K, et al. Accuracy of dynamic navigation for dental implant placement-model-based evaluation. J Oral Implantol. 2016;42(5):399-405. doi:10.1563/aaid-joi-D-16-00025 

6. Pellegrino G, Bellini P, Cavallini PF, et al. Dynamic navigation in dental implantology: the influence of surgical experience on implant placement accuracy and operating time. An in vitro study. Int J Environ Res Public Health. 2020;17(6):2153. doi:10.3390/ijerph17062153

7. Panchal N, Mahmood L, Retana A, et al. Dynamic Navigation for Dental Implant Surgery. Oral Maxillofac Surg Clin North Am. 2019;31(4):539-547. doi:10.1016/j.coms.2019.08.001

8. Cheng KJ, Kan TS, Liu YF, et al. Accuracy of dental implant surgery with robotic position feedback and registration algorithm: An in-vitro study. Comput Biol Med. 2021;129:104153. doi:10.1016/j.compbiomed.2020.104153 

ABOUT THE AUTHOR

Dr. Stonisch is a pioneer in dentistry with more than 2,000 continuing education credit hours earned and 3.5 decades of experience. Accredited by the American Academy of Cosmetic Dentistry, a distinction held by fewer than approximately 40 female dentists worldwide, Dr. Stonisch combines her experience with degrees in art and chemistry to produce smart, sophisticated smiles in her comprehensive dental practice in Grosse Pointe, Mich. She is a Diplomate in the International Congress of Oral Implantologists and a mentor at the Kois Center in Seattle. Dr. Stonisch was the 2017 recipient of the Excellence in Business Award given by her community. She was also the recipient of the 2018 Spiritus Award from her alma mater, the University of Detroit Mercy School of Dentistry. Dr. Stonisch has authored an easy-to-read, step-by-step guide to oral health and common dental dilemmas for consumers (patients) called Smile Fit, along with a companion workbook, Smile Fitness. She holds 3 patents for her SMILE-NOW peel-and-stick dental templates, which allow dentists as well as patients to quickly and easily see smile possibilities. She can be reached at thesmileartist@comcast.net. 

Disclosure: Dr. Stonisch reports no disclosures.