Over the years, we have all been witness to impressive evolutionary trends in our profession. Those of us whose careers have spanned 30 or more years have lived through the dawn, infancy, and now the heyday of implant dentistry. The major turning point that spurred the widespread success implants now enjoy was, of course, the core principle of osseointegration. To make osseointegration a reality, several early hurdles had to be overcome, such as establishing appropriate drilling parameters (temperature, load, speed, instrumentation) to produce a smooth bony implant bed while avoiding shrinkage.1,2 Preclinical studies in beagle dogs3 and miniature pigs4 provided data that formed the basis for human osseointegration clinical trials.
A Brief Historical Overview
Implant dentistry has long been the province of oral surgeons and periodontists, who still perform the majority of the surgical phase of osseointegrated implant (OI) placement. Even so, many oral surgeons, whose practices concentrate heavily on implant surgery (our office does not; OI placements make up about 35% of our practice), commonly do routine cases and reserve the more challenging ones for the academic environment or advanced specialty practices.
|Figures 1a to 1d. Typical case progression illustrates replacement of tooth No. 19, following osteotomy with Straumann drills; 2.2/2.8-mm Straumann depth gauge with distance indicator; Straumann alignment pins used (not shown). (a) A 4.2-mm Straumann depth gauge. (b and c) Blue SkyBio (BSB) One Stage wide-platform 4.8 x 10-mm implant fixture placed with BSB insertion tool and wrench. (d) A 1-mm BSB cover screw, tissue repositioned and sutured (full-thickness flap; note incision slightly to lingual to preserve attached gingiva on facial aspect). All drilling done with sterile irrigation.|
In the 1970s, when this author completed his oral surgery residency, implants were uncommon. Patients had fewer and frequently less desirable options back then: removable and fixed partial dentures, overdentures with endodontically treated teeth as abutments, or complete dentures.
Practitioners who are conservative by nature are not uncommon in any dental specialty. The implants of 4 decades ago consisted of blades and subperiosteals; while some were successful, implants as a treatment modality were not consistently predictable. Conservative practitioners of the day, preferring more traditional treatments that they already were familiar with, would discourage patients from considering implants.
|Figures 2a and 2b. Replacement of tooth No. 19 with a BSB wide-platform 4.8 x 10-mm fixture. (a) Bone shavings from flutes of drills placed around facial aspect of implant. Small piece of Foundation collagen membrane (J. Morita USA) placed over bone graft (not shown). (b) The 3-mm BSB cover screw placed, flap repositioned, and tissues closed with 4-0 chromic interrupted sutures. Note vertical anterior releasing incision to avoid exposure of the root of tooth No. 20, and further gingival recession. Oral and intravenous conscious sedation, nasal O2, electrocardiographic and pulse-oximeter monitoring used, plus local anesthesia (Septocaine [Septodont] with 1:100,000 epinephrine).|
|Figures 3a and 3b. Posterior bridge setup for teeth Nos. 3 to 5 showing Straumann 2.2/2.8-mm depth gauges seated in osteotomy sites. (a) Straumann 4.2-mm depth gauges. BSB One Stage fixtures No. 3 (4.8 x 10-mm regular platform) and No. 5 (4.1 x 12-mm regular platform) were placed (not shown). (b) Tops of 2-mm ImplantDirect (ID) healing cuffs, flared from 4.7 mm (platform) to 5.7 mm (occlusally; flares of cuffs not shown) used to preserve attached gingiva and improve implant margin exposure at impression transfer. Closure with interrupted 4-0 chromic sutures. Straumann drills were used, with sterile saline irrigation (as always).|
As early as 1990, studies making their way into respected journals were demonstrating long-term success for the osseointegration first achieved by the Brånemark systems, as described by Adell et al5 in a follow-up study of 700 edentulous patients who received OIs. This study had followed these patients for a maximum of 24 years, with overall prosthesis-stability rates of 92% and 99% (fixture survival rates of 78% and 86%) at 15 years, for maxillary and mandibular OI placements, respectively.5 Resistance slowly morphed into sparse acceptance, and in time, grew into a slowly-steepening curve of predictability and the widespread acceptance for OIs.
More recently, a concise review by Levin6 chronicles the evolution of implantology as more rapid than any other area of dentistry, and emphasizes clinicians’ reliance on the volume of research and scientific evidence to support any new procedure or technique. He summarizes that there is no shortage of science to suport the concept of osseointegration.
The Challenge of Affordability
One disturbing constant in the OI world is lack of affordability, especially in view of patients’ reliance on dental insurance coverage, which is meager at best, and still focuses on traditional treatments—often to the exclusion of OI coverage altogether, even though they have long passed the “experimental” stage.
Christensen7 recently advanced the case for making OIs more affordable, again, citing a high level of predictability and no lack of technology or research. He emphasized that expense and political “turf battles,” based upon perceptions and opinions of who should and should not be placing OIs, continue to stand between implants and patients who can benefit from them.
|Figures 4a and 4b. (a) Periapical view, root of tooth No. 20, tilted mesially at a steep angle, abscessed, and touching an existing implant (all other implants shown, including 2 adjacent implants, were placed by another clinician); patient desired immediate implant. Root was extracted, abscess excised. Narrow-platform (4.1-mm) BSB fixture placed subgingivally (not shown), remaining socket grafted with Puros (Zimmer Dental), covered with Foundation collagen membrane and 1-mm BSB cover screw (not shown). Note: regular-platform fixture would not have seated due to flare of its collar and lack of mesiodistal maneuvering space; direction of immediate implant osteotomy changed to parallel long axis of tooth No. 22 to avoid contact with molar implant. Primary closure with 4-0 interrupted chromic sutures, submerging implant, graft, and cover screw (not shown). (b) Postoperative periapical view of implant in No. 21 position. This case was successfully restored after 20 weeks. Narrow-platform fixture may allow impression transfer to seat without porcelain reduction on overcontoured adjacent molar crown.|
In this context, the simpler OI placements such as bridge setups, single-tooth replacements, and overdenture abutments are keeping oral surgeons busy. In this author’s geographic area, few general practitioners (GPs) are actually placing implants; as an oral surgery practice, our main implantology focus remains on surgical setups required by the local dentists who will restore them. Now, just as most GPs are routinely restoring OIs, the surgical world of osseointegration is beginning to encompass GPs as well. Most of the simpler cases done in our office could probably be done by a restorative dentist with appropriate training and familiarity with the variety of specific implant systems in use. Primary reasons behind this expansion of skills are the increasing levels of simplification and cross-platform compatibilities that have evolved across various OI systems and manufacturers.
Our office began placing implants in the late 1980s, and during the years we have used a broad variety of systems including: hollow basket design; Calcitec hydroxyapatite-coated smooth-sided (Calcitek Spline [Sulzer Calcitek]); Endopore (Innova); (Nobel Perfect One-Piece [Nobel Biocare]); Straumann; IMTEC mini; Sybron TL and XRT (ImplantDirect); and other ImplantDirect products.
As systems evolved, we had successes and failures with very little consistency. We first started to notice consistent predictability with the use of Straumann systems. Prior to about 2004, there were still some issues, most notably screw fractures, which seldom happen nowadays. In 2005, we increased our clinical use of BlueSkyBio (BSB) implant platforms, largely because of their cost savings, which we can pass on to our patients. Moreover, BSB implants are compatible not only with Straumann synOcta (we use the BSB Bio One Stage the most) and other systems, but with NobelReplace (BSB Bio Trilobe) and Zimmer Tapered Screw Vent (BSB Bio Internal Hex) systems as well. We also use the XRT bone level (ImplantDirect), and the Spectra System and Legacy 3 fixtures (ImplantDirect).
|Figures 5a to 5d. Tooth No. 11 is replaced using the Zimmer-compatible Legacy 3 system (ImplantDirect). (a) Full-thickness flap exposes osteotomy site. Straumann alignment pin used (not shown). (b) Straumann 2.2/2.8-mm depth gauge with distance indicator. (c) ID driver mount (which can ultimately function as an abutment) used to place 3.2 x 11.5-mm ID Legacy 3 fixture (3.0 platform on implant expands to larger platform on abutment). Hexagonal-attachment fixture placed at bone level (not shown). (d) ID cover screw placed.|
Simple instrumentation makes for simplified OI placement, and also helps keep costs down. A less expensive OI (such as BSB) has its own surgical kit, but the clinician can also use the Straumann kit. A mountless design eliminates the extra step of engaging and detaching the more commonly used driver mount. BSB’s handheld insertion tool is torqued via a thumbwheel, fits inside the implant, and can be used multiple times; this simplifies the placement in the osteotomy site and also allows reversal of the implant if necessary.
When drilling in the mandible, rotational torque tends to pull the tip of larger-diameter drills either facially or lingually depending upon bone density and pressure applied to the drill. If drilling guides are not used, the osteotomy can be deepened gradually with finger rests bracing the handpiece, using irrigation, and very light pressure.
At one time, the concept of platform switching might have suggested the use of different implant components from a number of manufacturers. Levin6 describes this concept in terms “mismatching”; that is, using abutments that are smaller than the heads of the implant fixtures on which they are placed, suggesting that such hybridization might actually offer benefits. This may redistribute occlusal forces to the implant itself, thereby relieving stress on the abutment; this observation is based on the use of solid abutments, which comprise most of our cases. Now well accepted, platform switching within a particular implant system is now commonly available. Indeed, 2 recent randomized trials by Canullo et al found greater marginal bone level preservation in applications that used platform switching,8 and also observed good soft-tissue health around platform-switched abutments.9 A recent study by Calvo-Guirado et al10 also observed good crestal bone preservation with platform-switching, reporting a 5-year OI survival rate of 97.1%. A recent review by Serrano-Sánchez et al11 found widespread agreement that platform switching is associated with crestal bone preservation.
|Figures 6a and 6b. Finished restorative case shows BSB Bio One Stage implants and BSB solid abutments in the Nos. 18, 19, and 20 positions. BSB 3-mm cover screws were placed over 6.5 x 8-mm (wide platform; molars) and 4.1 x 10-mm (regular platform; premolar) BSB implants (not shown). a) Periapical view of finished implants, abutments, and restorations. b) Aesthetics of finished restorations.|
Most manufacturers are beginning to signal compatibility with components of other manufacturers; compatibility with Straumann systems usually receives the most attention.
Overdenture Implant System Cross-Compatibility
Cross-platform compatibility among manufacturers and components of implant-based overdenture systems also helps ease patients’ cost burdens. This often provides the flexibility that can make the difference between offering a service and not offering it.
|Figures 7a to 7c. Anterior aesthetic results after replacement of tooth No. 7, using BSB Bio One Stage implant and BSB solid abutment. (a) Angulation problem (fixture and abutment tipped too far facially) corrected via laboratory fabrication of reduction coping (not shown). (b) Postoperative periapical view. (c) Finished restoration.|
The Zest Locator-type attachment (Zest Anchors) is compatible with the BSB 3.3-mm diameter implant. The Master Overdenture Restorative Kit (BSB) includes the implant, attachment, and components for impressing in one kit. Other implant sizes include the regular 4.8-mm diameter, and the narrow-platform design (4.1 mm), which is well-suited to areas without adequate mesiodistal dimension.
Documenting Implant Failures
Our practice has placed more than 642 OIs since 2005 that are functioning successfully. Although distressing, it is just as important to chronicle the failures experienced with OI placements, along with the probable causes of failure.
Between 2005 and late 2010, we experienced OI failures in 6 patients. Two failures involved immediate placement after extraction of a fractured endodontically-treated tooth. Residual infection was probably present around the root. After thorough debridement, Foundation (a collagen-based bone augmentation material [J. Morita USA]) was placed in the socket, and the retreatment OI placement was successful.
|Figures 8a to 8c. Premolar restorative case shows tooth No. 4, replaced using BSB Bio One Stage implants and BSB solid abutment.Full-thickness flap with BSB 4.1 x 10, 4.8-mm platform fixture (not shown); 3-mm BSB cover screw placed; closure with 4-0 interrupted chromic sutures (not shown). (a) BSB solid abutment placed. (b) Postoperative periapical view. (c) Finished restoration.|
Cement from the restorative phase can interfere with integration. One failure involved OIs on teeth Nos. 14 and 15; No. 14 was successful, but No. 15 was loose and surrounded by granulation tissue. Cement was discovered in its threads after removal, having likely caused an inflammatory reaction. Again in this case, after debridement, Foundation was placed; however, the patient did not want OI retreatment of the No. 15 site.
Two other cement-related failures occurred recently, probably by a similar mechanism. This highlights the need for the GP’s vigilance before and during cementation to minimize subgingival cement expression, either by occlusal venting or minimal cement application. It is this author’s opinion that subgingival cement expression may cause a granulomatous reaction at the critical early stage of integration.
|Figures 9a to 9c. An 80-year-old female patient has had teeth replaced in our office during the past 15 years using various implant systems. (a) Laboratory-customized BSB synOcta (Straumann)-compatible abutments were attached to BSB Bio One Stage 4.8-mm regular-platform fixtures to replace teeth Nos. 9 to 13. (b) Postoperative panoramic view showing implants from various manufacturers including Endopore (Innova) and Straumann (lower left posterior, upper right posterior implants are Endopore [Innova] fixtures; No. 6 is Calcitek Spline [Sulzer Calcitek] fixture). Most recently placed fixtures are BSB Bio One Stage with synOcta-compatible solid abutments shown above. (c) Finished restoration.|
Another OI was placed in an area with very little bone and never integrated. It was removed and the socket augmented with Foundation. Retreatment OI placement was successful.
In June 2011, a patient with 3 successfully restored BSB implants placed in our office several years ago had 2 more BSB implants placed in the Nos. 11 and No. 13 positions. Three months later, the No. 13 implant (not restored yet) exhibited mobility and lack of integration. The fixture was easily removed, and the socket augmented with Foundation collagen. We planned to place another implant in 12 weeks, submerge it for 6 months, and reassess. The implant at the No. 11 site remains solid. Occlusal forces from a temporary partial denture base (which rested on the No. 13 cover screw), had probably caused micromovement and the eventual failure of the implant.
Occlusal anomalies are thus a critical consideration by the GP placing or restoring OIs. Implant overload, heavy occlusal forces, and parafunctional habits have contributed to the majority of OI failures in our office. Socket grafts (with materials such as Foundation and Puros [Zimmer Dental]) and socket preservation are essential after extractions if OIs are to be done later.
The cases reported here are from our oral surgery practice, and the majority of them (642 documented fixture placements) involve BSB One Stage, which is Straumann synOcta compatible. One case demonstrates ImplantDirect’s Legacy 3 system. Figures 1a to 5d illustrate typical case progressions and uses of various BSB and other systems. Figures 6a to 9c show restored BSB cases.
How Critical Is Integration Time?
Length of integration time is frequently a function of the clinician’s comfort level, ie, a preference factor. In our office, we prefer on average about 20 weeks, but all of our immediate loads have also worked well. Immediate loading is what many clinicians are doing, and what patients want.
Some data suggest that proprietary surface treatments (like chemically modified sandblasted, acid-etched surfaces) may favor shorter integration times,12 and thus may offer a safe, biocompatible hedge. Another line of reasoning (for longer integration times) usually envisions the dreaded case in which an implant fails to integrate because of occlusal forces (such as failure described above). This necessitates further expense for both clinician and patient, and the discouraging scenario of having to start over. Most patients in our practice are willing to wait for a longer period if our comfort level suggests they do so (and it usually does).
Clinicians are beginning to see more patients in their 80s, often on fixed incomes, who began receiving implants in their 70s. Some have multiple systems in place, and all those we see are all doing well. We communicate the shared-care option (between surgeon and GP) clearly to all of our OI patients. In addition, we emphasize the importance of regular (ongoing) follow-up and maintenance of their OIs.
In summary, OIs should be a treatment option for anyone who presents for tooth replacement. In addition, it is the author’s opinion that both placing and restoring implants belong in general practice. Economic conditions are beginning to dictate that anyone graduating from dental school must be familiar with at least restoring but also placing OIs. Systems are now much more similar than they are different. Cross-compatibility among mutliple manufacturers, along with platform switching, are enabling more clinicians to bring high-quality implants to a broader segment of patients.
The author thanks Scott A. Saunders, DDS, ELS, CMPP, for providing professional medical writing/editing services in preparation of this article.
- Reingewirtz Y, Szmukler-Moncler S, Senger B. Influence of different parameters on bone heating and drilling time in implantology. Clin Oral Implants Res. 1997;8:189-197.
- Sutter F, Krekeler G, Schwammberger AE, et al. Atraumatic surgical technique and implant bed preparation. Quintessence Int. 1992;23:811-816.
- Weber HP, Buser D, Donath K, et al. Comparison of healed tissues adjacent to submerged and nonsubmerged unloaded titanium dental implants. A histometric study in beagle dogs. Clin Oral Implants Res . 1996;7:11-19.
- Buser D, Nydegger T, Oxland T, et al. Interface shear strength of titanium implants with a sandblasted and acid-etched surface: a biomechanical study in the maxilla of miniature pigs. J Biomed Mater Res. 1999;45:75-83.
- Adell R, Eriksson B, Lekholm U, et al. Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac Implants. 1990;5:347-359.
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- Christensen GJ. Implants: Expensive turf privilege or service to patients? Dental Economics. 2008;98:123-456.
- Canullo L, Fedele GR, Iannello G, et al. Platform switching and marginal bone-level alterations: the results of a randomized-controlled trial. Clin Oral Implants Res. 2010;21:115-121.
- Canullo L, Pellegrini G, Allievi C, et al. Soft tissues around long-term platform switching implant restorations: a histological human evaluation. Preliminary results. J Clin Periodontol. 2011;38:86-94.
- Calvo-Guirado JL, Gómez-Moreno G, López-Marí L, et al. Crestal bone loss evaluation in osseotite expanded platform implants: a 5-year study. Clin Oral Implants Res. 2011;22:1409-1414.
- Serrano-Sánchez P, Calvo-Guirado JL, Manzanera-Pastor E, et al. The influence of platform switching in dental implants. A literature review. Med Oral Patol Oral Cir Bucal. 2011;16:e400-e405.
- Bornstein MM, Wittneben JG, Brägger U, et al. Early loading at 21 days of nonsubmerged titanium implants with a chemically modified sandblasted and acid-etched surface: 3-year results of a prospective study in the posterior mandible. J Periodontol. 2010;81:809-818.
Disclosure: Dr. Poporad reports no disclosures.