Osseotite NT Implants for Optimal Stability and Aesthetics
Alan Meltzer,DMD, MScD
The success and predictability of implant therapy have significantly expanded the range of treatment options available for fully and partially edentulous patients. As a result of the continued evolution of surgical protocols, material technologies, and implant designs, tapered implants represent the standard of care for increasing numbers of implant candidates. Their favorable primary stability and simplified but altered placement procedures reduce the cost and duration of implant treatment. This article demonstrates the inherent principles associated with Osseotite NT tapered implants (3i Implant Innovations, Inc, Palm Beach Gardens, FL) and presents considerations for their successful delivery and integration.
Dental Implants have significantly expanded the range of treatment options available for the restoration of the fully and partially edentulous patient. The surgical protocols and the armamentarium for implant therapy have continued to evolve, and the potential for successful treatment has increased in kind. Where function was once the predominant goal of implant treatment, biocompatibility had aesthetics are now required as well. One example of the fields continued advancement is the tapered implant.
Tapered implants were originally slated for use in extraction sockets, convergent root systems, and in areas with deep facial concavities. In such situations, tapered implants were believed to promote integration and maximize the use of available osseous tissue support without the requirement for bone grafting, perforation of the bony housing, or damage to adjacent roots. Furthermore, the macrogeometric alterations in shape, thread pitch, path, and self-tapping design achieve primary stability far beyond that achieved my classic cylindrical implant designs. While such benefits did expand on the indications of cylindrical implants, none conveyed the more meaningful benefits of tapered implants. Since been introduced to the concept in 2001, this authors use of tapered implant has grown significantly as each of its less known benefits have been more fully realized.
Contemporary tapered implants such as the Osseotite NT (3i Implant Innovations, Inc., Palm Beach Gardens, FL) provide numerous clinical advantages:
High primary stability
Simplified clinical protocol (for insertion)
Reduced risk of intraoral contamination
Reduced need for hard tissue site enhancement
In order to harness the benefits of tapered implants, the clinician must have a thorough understanding of the implants inherent design criteria as well as the procedures that enable its application. Using detailed clinical photographs and anatomic illustrations; this article discusses the concept of tapered implants and demonstrates their placement through a simple, predictable process aimed at improving the clinicians ability to deliver them accordingly.
High Primary Stability
The dental patient and practitioner each stands to benefit from the unique characteristics of the Osseotite NT implant. As highlighted previously, this tapered design achieves high primary stability upon insertion, even when placed in bone of poor quality. This can be attributed to the high tolerances between the implant and the shaping drill as well as the precise implant-to-osteotomy fit within an extraction site. The surgical drills have three cutting flutes that are shaped specifically to replicate the shape of the implant without its threads, which, when seated allow the implant to engage the bony wall of the site. Thus, the requirements of high primary stability (i.e., 60 ISQ to 70 ISQ [Ostell]) and low insertion torque are achieved by the author in all bone qualities. Rather than requiring the use of implants with maximum length, this stability- coupled with the dual, acid-etched Osseotite surface-allows the clinician to select tapered implants with shorter lengths. Additionally, the added feature of uniform threads to the apex aids in maximum engagement of all available bone. This is a feature of major importance when placing tapered implants in an extraction site.
Simplified Drilling Protocol
The simple clinical protocol used to seat the tapered implant represents an additional benefit to the dental professional. For crestal placement, the clinician progresses from the round bur first to the 2-mm twist drill, then to the pilot drill 9this step is mandatory in the authors experience), and then directly to the final shaping drill, which ids dependent upon the quality of bone as well as the diameter and length of the implant selected. Thus, for insertion of a 4 mm X 10 mm implant, the clinician can use the round bur, twist drill, pilot drill, and then proceed directly to the 4-mm shaping drill of the desired depth, while eliminating the inclusion of the 3.25-mm shaping drill. This drilling procedure for the Osseotite NT (3i, Palm Beach Gardens, FL) affords the treatment team ease of placement throughout the surgical phase. In the authors experience, evaluation of the bone contained within the flutes of the 2-mm twist drill provides invaluable information about the quality of the osteotomy site. If, following the use of the 2-mm twist drill, bone is firmly imbedded within its flutes; the clinician should use the appropriate shaping drill (i.e. 4 mm X 13 mm implants require 4 mm X 13mm shaping drill). If following the use of the 2-mm twist drill, the flutes are coated with fatty marrow (e.g., vinegar and oil appearance), the practitioner should downsize the shaping drill (i.e., 4 mm X 13 mm implant, use the 3.25 mm X 13 mm shaping drill as the final drill); then proceed directly to implant placement. In either case, the implant should be seated using 20 rpm at 40 Ncm sq. The author also routinely completes placement with the hand ratchet to optimally position the implant platforms in order to maximize primary stability and fulfill the desired functional and aesthetic position.
Rapid Implant Placement
As a result of the simplified clinical protocol, rapid placement of the implant can be achieved. Using a cylindrical implant design for the replacement of a maxillary central incisor, the author is able to seat the conventional implant in approximately 75 seconds, during which saliva or the surgical flap has the potential to contaminate the implants surface. With the Osseotite NT tapered implant system in a comparable site, the implant drops approximately three quarters into the osteotomy site and can be torqued into place (20 rpm at 40 Ncm sq.) with four simple turns in approximately 15 seconds with improved primary stability (57 ISQ for cylinders as compared to 68 ISQ).
As a result of such rapid placement with the tapered implant, there may be concern regarding its primary stability. In the authors experience, however, this is completely unfounded. Using conventional cylindrical implants, it is often possible for the clinician to continue turning the hand ratchet to achieve greater (though unnecessary or undesired) depth of insertion. Due to the close adaptation between the shaping drills and the implants of the tapered Osseotite NT implant system, it is essentially impossible for the surgeon to further twist the implant with the hand ratchet once it is fully seated. This advantage can be partially attributed to the unique design of the .0-mm-thread pitch of the tapered implant (in comparison to the .6 mm for the cylindrical implant). Furthermore, the domed apical end, coupled with the variable aspect ratio taper, provides a firm final position.
Reduced Risk of Intraoral Contamination
At the conclusion of the drilling protocol and, due to the speed by which the Osseotite NT implant can be seated, the entire surface of the implant-even prior to rotation- is already three quarters of the way into the osteotomy site. This reduces the potential for intraoral contamination by reducing the time the implant surface is exposed to the oral environment. In addition, the implants entire Osseotite surface is submerged in the site and is immediately coated with the patients own blood, which increases the potential for fibrin clot attachment, osseointegration, and overall success. After three or four turns of the handpiece at 40 Ncm, the implant will be fully seated, which greatly reduces treatment length and the risk of surface contamination from the patients saliva, the surgical flap, or other iatrogenic factors. The author routinely used the hand ratchet to verify the final seating. While it may require one to two additional turns to reach the final position, this hand torquing is critical, in the authors opinion. This ability of the Osseotite NT implant to initially drop into the site makes it an ideal candidate for flapless surgery.
DESIGN FEATURES OF THE OSSEOTITE NT
The Osseotite NT has several design features that contribute to its success in aesthetic, implant-supported restorations. First, it has a color-coded seating surface for simple identification of the implants platform dimension. This tapered implant also has uniform threads to its apical end, a design characteristic unique to the Osseotite NT, which can provide stability even in the compromised implant sites including extraction sockets. Its domed apical end reduces the potential for apical soft tissue trauma, a features that is particularly relevant for use in conjunction with sinus lifts. The implant also has a classic Osseotite hybrid surface design for long-term peri-implant health, a favorable shape-variable taper aspect ratio, and a Spiral ICE self-tapping feature that permits low insertion torque while achieving high primary stability. In addition to being available in the external hex design, the Osseotite NT implant is also available in the new Osseotite Certain internal connection with a complete line of prosthetic parts and options.
Further, the Osseotite NT is differentiated from other implants by related design characteristics. This implant has a distance of 2.5 mm from the prosthetic platform to the first thread; on classic Osseotite implants, this distance is 2.3 mm. This .2-mm difference is attributed to the thread pitch of each, which measures of .9 mm and .6 mm for the Osseotite NT and the Classic, respectively. The distance from the prosthetic platform to the start of the Osseotite surface is 3 mm in both cylindrical and tapered implant formats. Additionally, the Osseotite NT can be seated with 21% to 70% less insertion torque than can other tapered implants as a result of the precision fit between its shaping drills and corresponding implants.
PRELIMINARY DATA ON THE SUCCESS OF THE OSSEOTITE NT IMPLANT
The author has achieved a 99.3% success rate for 107 consecutively placed NT implants, all performed from July 2002 through December 2002. Each of the implants (predominantly of shorter length and of the 4-mm platform) was placed in full occlusal function no later than February 15, 2003. Implant placement was accomplished in the mandibular anterior and posterior regions. According to loading protocol, 18 of 107 implants were immediately loaded, 12 were placed via two-stage surgery, and 77 were placed by a single-stage procedure using a two-piece transmucosal-healing abutment. The only implant lost was a 4 mm X 10 implant, which was a spinner at the time of placement.
Discussion of Preliminary Data
Despite the fact that data only relate to a short follow-up period, certain preliminary conclusions can be made. First according to the literature, most failures with Osseotite implants have occurred at stage-two surgery either upon uncovering or removal of the healing abutment. Thus, with the Osseotite NT implants, one would not expect to find many failures subsequent to uncovering. Further longer term follow-up is necessary, however, and underway. To date, up to one year postloading and 10 months postplacement, only one implant has been lost at stage two. This was the authors third implant placed and, in the authors opinion, was related to overpreparation of the osteotomy site with soft bone.
Second, failure rates of short maxillary posterior implants with poor stability placed in type 4 bone (often termed spinners) are extremely low. Therefore, if an Osseotite implant reaches the loading phase, existing long-term data supports an expected 99%+ survival rate even under these most demanding circumstances. Thus, extrapolating from these data, very few failures should be expected with the Osseotite NT following long-term loading.
Unlike standard cylindrical implants, resonance frequency analysis values for the primary stability of NT implants are consistently high throughout all regions of the mouth, regardless of bone quality. The author does, however, recommend an altered drilling protocol in types 3 and 4 bone. This high mechanical, primary stability, coupled with low insertion torque, suggests that the NT implant could be used in support of immediate loading procedures- 18 of the 107 implants placed were immediately loaded and had 100% short-term success. Prospective controlled studies to test the hypothesis are underway.
Naturally tapered implant designs have an obligatory macrogeometric decrease in surface are over cylindrical implants. Surface area comparisons of the tapered NT to the traditional Osseotite show there is a 20% loss of area between the 3.75-mm implants, and approximately 30% less surface area at the 4-mm-diameter size. By selecting a 4-mm Osseotite NT implant instead of a 3.75-mm classic cylinder of the same length, however, provides virtually the same surface area. Furthermore, the use of the tapered implants often allows the practitioner to bypass certain anatomical structures and permit the use of longer implants to compensate for the loss of surface area due to the taper (personal communication, D. Rogers, 6/03). Nevertheless, the Osseotite surface demonstrates high bone-to-implant contact, making any loss of surface less of a concern. Overall, bone to implant contact is more of an issue than implant surface area. Further, comparison of success rate confirms that short Osseotite implants perform virtually as effectively (non statistically significant differences) as do implants of greater length. Preliminary data demonstrate the Osseotite NT implant is also to be one of the only implants that functions as well in the wide platform as it does in the standard-diameter platform.
The use of tapered implants can provide aesthetic-minded clinicians with numerous benefits that contribute to their success and long-term function. This article has demonstrated the high primary stability, simple drilling protocol, reduced insertion time, and decreased risk of contamination associated with the Osseotite NT implant (3i, Palm Beach Gardens, FL), with the goal of facilitating its increased use for implant-supported restorations. While larger long-term studies will be necessary to measure the clinical performance of these implants, the preliminary results and data appear promising for dental professionals and their patients.