- Email: [email protected]
Early Clinical Experience With a New One-Piece Implant System in Single Tooth Sites
SINGLE TOOTH IMPLANT RESTORATIONS J Oral Maxillofac Surg 63:2-10, 2005, Suppl 2
Early Clinical Experience With a New One-Piece Implant System in Single Tooth Sites Stephen M. Parel, DDS,* and Sterling R. Schow, DMD† Purpose: To evaluate the clinical efficacy of a new 1-piece implant in single tooth sites. Materials and Methods: Early clinical results were evaluated through observation and collection of
survival data for 45 1-piece Direct implants (Nobel Biocare, Yorba Linda, CA). Patients ranged in age from 19 to 54 years, of which 23 were women and 12 were men. Both anterior and posterior single tooth defects were treated, with the majority being in the maxillary anterior zone. Five of the 45 implants placed were in immediate extraction sites. Observation periods ranged from 2.5 to 32 months. Results: One implant failure was detected over the observation period. It occurred in a maxillary lateral incisor site, and was placed and immediately loaded after tooth extraction. The overall success rate was 97.8%. Conclusion: Within the limited parameters of this study, it can be concluded that the 1-piece implant design can be used effectively as a basis for restoring single tooth defects. Longer observation periods, more detailed soft tissue analysis, and larger numbers of implants in varied arch sites will be required to establish definitive protocols for the use of this implant. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:2-10, 2005, Suppl 2 While 1-piece implants are not new to implant dentistry, recent variations from these early designs have created a renewed interest in the unibody concept for both provisional restoration support and permanent application.1-7 The implant evaluated in this report was designed to be used with a flapless approach and has a unique surface application not previously seen in existing 1- or 2-piece designs.
cations have been challenged as 2-piece designs due to strength of components when the diameter approaches the 3 mm level. Either the abutment screw is too small to be sufficiently load-bearing, or the space required for a larger abutment screw will leave the internal side walls of the implant insufficiently thick. Both of these concerns are overcome by a 1-piece design. Another unique feature of this implant is the creation of a rough surface through the soft tissue space as a means of encouraging soft tissue integration and biologic seal. While the long term effects of this design on tissue health are not yet known, initial investigations would support the efficacy of this concept.8,9
Design Features The need for small diameter implants presents on occasion in narrow, single tooth spaces such as maxillary lateral incisors or mandibular incisors. Some previously available narrow implants for these appli-
Materials and Methods
Received from Baylor College of Dentistry - Texas A & M University Health Science Center, Dallas, TX *Professor and Director, Center for Maxillofacial Prosthodontics. †Professor and Director of Residency Training, Department of Oral & Maxillofacial Surgery and Pharmacology. Address correspondence and reprint requests to Dr Parel: Baylor College of Dentistry, 3302 Gaston Ave, Dallas, TX 75246; e-mail: [email protected]
Forty-five single tooth sites were treated with a new 1-piece implant, The Nobel Direct (Nobel Biocare, Yorba Linda, CA), using a flapless surgical approach. The patient ages ranged from 19 to 54 years, with 23 female and 12 male participants. Six patients had more than 1 implant placed, with all sites being isolated and bordered by natural dentition. The overall treatment period ranged from 2.5 to 32 months, with a mean observation period of 14 months.
© 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/6309-0202$30.00/0 doi:10.1016/j.joms.2005.05.150
2
PAREL AND SCHOW
FIGURE 1. This healed site for a maxillary lateral incisor has good bone width, existing interdental papilla position, and normal bone height on adjacent tooth surfaces (not shown radiographically). Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Anterior Dentition For single tooth application, fixture location components have been designed that may eliminate the need for conventional prefabricated surgical guides. A slide-over guide sleeve can be used with the initial 2 mm twist drill osteotomy to help visualize the position of the eventual implant coronal extension (Figs 1-3). A tissue punch guide can then be placed into the 2 mm osteotomy to serve as an axial guide for the circular tissue trephine (Figs 4-6). Nearly complete soft tissue removal is essentially accomplished using this rotary instrument to the crest of the alveolar bone. A sharp curette or spoon is used to remove the tissue remnants at the crestal surface that were not severed by the handpiece instrument. One of the significant benefits of this particular flapless approach is the creation of the initial free gingival margin at a
3
FIGURE 3. The surgical guide slips over the 2 mm twist drill and is used as a visual reference as the initial osteotomy is performed. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
low level relative to the adjacent marginal gingiva. This will allow vertical room for manipulation of the semi-lunar soft tissue during provisionalization, thus minimizing the possibility of creating an initial margin position at an undesirable apical level. With time and healing, this margin will generally migrate apically approximately 1 mm as a natural occurrence.10-12 Using this tissue manipulation concept, this apical migration will generally not present an esthetic compromise because the starting position of the marginal gingival was created coronally by design. Completion of the osteotomy site is accomplished using the drill sequence appropriate for the size implant anticipated in this site (Figs 7, 8). The implant taper corresponds to the Replace Select product line (Nobel Biocare), so the existing Select drill set can be used for the Direct implant as well.
FIGURE 2. The surgical guides represent the basic shape of the various implant coronal surfaces and have a hollow central core.
FIGURE 4. Tissue punch guides are color coded to correspond with implant sizes, with an extension apically that anchors in the 2 mm osteotomy.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 5. In position, the punch guide allows the tissue removal to be consistent with the long axis of implant placement.
FIGURE 7. The initial 2 mm osteotomy is expanded to a width appropriate for the diameter of the implant to be placed.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Implant position is important in either arch, and is especially critical in the esthetic zone. For long term tissue maintenance, every attempt should be made to keep the fixture long axis slightly to the palatal aspect of the edentulous space and to avoid a facial tilt or flare to the implant.13 This concept applies to an even greater degree in immediate extraction/immediate load cases, where the tendency is to follow the apical socket contour, which may direct the implant to a less desirable facial orientation. Implant placement is completed using machine torque initially and hand wrench final torque as necessary to the eventual desired position (Fig 9). Stargrip drivers engage the coronal internal surface for all but the 3 mm design, and are used exclusively to deliver these implants. Because the coronal diameter of the 3 mm implant is too narrow to accommodate an internal drive connection, an external socket
driver that engages the axial bevel on the implant head is used as the fixture mount for this series. Upon complete seating of the implant and verification of an acceptable initial stability, the occlusal clearance is evaluated in centric position. Gross reduction of the occlusal surface using multi-fluted carbide burs is the only recommended intervention at this stage, which makes space for the provisional restoration as needed (Fig 10). Modification of the axial surfaces for contour or margin definition is delayed until the implant has completely integrated. The provisional restorations can be completed most practically as a chairside procedure using prefabricated shell crowns or the laboratory produced equivalent. It is important that the relining procedure involve multiple “on-off” maneuvers as the resin is setting to avoid entrapment of cured resin subgingivally. Once the final set has been achieved, the provisional crown should seat and unseat without exces-
FIGURE 6. The rotary trephine creates a clean soft tissue opening, but will generally require subsurface curettage to expose a circumferential bone surface.
FIGURE 8. The 1-piece Direct implant (first generation) has a tapered profile and a rough surface through the soft tissue zone.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
PAREL AND SCHOW
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FIGURE 9. Implant placement (with the exception of the 3 mm size) is completed to final position using a star-grip driver and mechanical or hand torque as required.
FIGURE 11. The provisional shell crown is initially indexed with resin intraorally, and is finished on a similarly reduced analog implant to a desired uniform margin depth and contour.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
sive vertical force being required. Final margin position can be completed on an analog implant, with subgingival extension ideally approximately 1 to 1 1/2 mm circumferentially (Figs 11, 12). Provisional restoration occlusal contacts should be grossly absent in centric position and all excursive movements, even if an under-extended incisal edge needs to be created (Fig 13). Embrasure contacts should also be light. A provisional cement is used for luting, and crown removal, unless absolutely necessary, is avoided for at least 3 months. Patients are advised to avoid this site when chewing, and to stay on a soft diet for at least 2 weeks. Following successful integration, usually at 3 to 4 months, the provisional is removed and sulcus depth is evaluated (Fig 14). On the larger diameter implants, 4.3 and 5.0 mm, it is possible to create a facial finish
line subgingivally using specifically designed carbide burs and copious irrigation (Figs 15, 16). It is impossible to avoid tissue damage during facial recontouring, so the provisional should be relined to the new finish line and recemented for at least 3 weeks for tissue recovery (Fig 17). Experience to date has shown no adverse residual effects from the tissue trauma caused by preparation of the coronal extension. For the smaller diameter implants (3.0 or 3.5 mm), any necessary sulcus extension needed for profile is accomplished by extending the provisional margin and waiting several weeks for tissue resolution before impressions. Handpiece reduction on these smaller implant abutment axial surfaces is not recommended. Whether retraction is needed for final impressions is determined by the health and stability of the tissue at the follow-up appointment. Because of the more
FIGURE 10. Initial reduction is for occlusal clearance only using specifically designed multi-fluted carbide burs. Axial reduction is not recommended at this stage.
FIGURE 12. The initial restoration is cemented with a provisional cement of choice.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 13. Occlusal contact is grossly absent in centric position and all excursive movements. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
rigid tissue integration commonly seen against this rough surface, it will feel like more pressure than average is needed to place retraction cord. Fortunately, any disruption of the hemi-desmesomal attachment recovers without complication following cord removal (Fig 18). The definitive crown is fabricated using conventional means, usually with a porcelain-fused-to-metal approach (Fig 19). Final cementation is performed conventionally using a long term cement of choice (Figs 20, 21). The same approach for final crown construction is used for the 3.0 mm implant option with the exception of the need for margin preparation as noted above (Figs 22, 23).
Posterior Applications Specific design changes with a flat, preformed margin make this implant very effective in the premolar
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 15. Narrow, rounded carbide finishing burs are used to create a finish line subgingivally, generally on the facial-axial surfaces only. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
and molar regions (Figs 24, 25). It is possible, in fact, to complete a single tooth restoration without the need for a driver or handpiece for metal reduction when using this implant option. This technique requires that the implant be placed apically enough initially to have sufficient clearance for provisionalization as previously described, and to allow placement of the margins uniformly subgingivally (Fig 26). The preformed margin is not scalloped, so use in the esthetic zone is not advised. However, in posterior areas with flatter embrasure contour, this horizontal margin design is acceptable, and facilitates a simplified approach to impressioning and final restoration with improved emergence profile (Figs 27, 28).
Discussion Early clinical experience with this implant has been encouraging (97.8% overall) with regard to implant
FIGURE 14. After 3 to 4 months of healing, the implant is evaluated for integration. Note the positive changes in soft tissue volume interproximally, and the apical migration of the free gingival margin.
FIGURE 16. The coronal surface has been modified with a subgingival finish line on the facial aspect.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
PAREL AND SCHOW
FIGURE 17. Following margin preparation, reprovisionalization with a relined temporary is usually necessary for tissue resolution. An additional healing period of 3 to 4 weeks is recommended. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
success (Tables 1, 2). It is important, however, to consider the implications of a flapless approach, especially in the esthetic zone, when evaluating these results. A flapless approach has been shown to have inherent benefits in soft tissue preservation, particularly for the interdental papilla, in a variety of applications.14,15 It has also been documented to be a safe procedure in terms of implant success, with percentages equivalent to healed site and delayed loading protocols.15-22 There is, however, no data that would support a predictable esthetic outcome on a consistent basis simply by using a flapless technique.10,16,17,23 Inability to directly visualize the path of the osteotomy and eventual implant placement position may also result in undetected fenestration or minor dehiscence apically. While this is not necessarily a precursor to implant failure, it can generally be
7
FIGURE 19. The completed crown has been constructed with a ceramic facial margin to maximize cervical translucency. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
minimized or avoided as experience increases with this technique.24 It is of interest to note that the only failure resulted from implant placement in an extraction site. The efficacy of a flapless approach in many of these situations will be dictated by the presence of a contiguous buccal plate at a reasonable distance from the free gingival margin (4 mm) and an implant bone-gap of less than 2 mm.19,25-27 Because there is insufficient evidence to predict an esthetic result at the extremes of these parameters, it is currently recommended that a socket preservation procedure be performed with delayed implant placement until sufficient data are available to support an alternative procedure. Without the flexibility of an interchangeable abutment, the initial positioning of this implant in the esthetic zone becomes even more critical with a 1-piece design. If space is not created facially for restorative materials to emerge with natural contours,
FIGURE 18. The final impression records the sulcus depth and margin preparation, usually without the need for extensive retraction.
FIGURE 20. The clinical result at 1 month following crown delivery.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 21. Radiographic view of the integrated implant and resultant bone position 1 year from date of placement. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
there may be a tendency for the marginal gingival to “creep” apically, resulting in a longer than desired clinical crown appearance.13 Thus, experience and expertise in sagittal and vertical implant positioning will play a role in this aspect of the surgical learning curve. It is important to also consider patient selection with regard to gingival biotype profile.28 Because of the highly adherent nature of the soft tissue to the extended implant rough surface, there may be a greater tendency for eventual gingival discoloration in patients with thin overlying keratinized epithelium. In diagnosing candidates preoperatively for this procedure, it may be necessary to incorporate a “roll-over” or free subepithelial connective tissue graft proce-
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 23. Radiographic position of a restored 3 mm 1-piece implant illustrates the space available for adjacent bone structure with minimal papilla encroachment. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
dure into the treatment plan if adequate thickness of overlying gingiva is not present. The 1-piece permanent implant represents a significant departure from the time-tested 2-piece approach both philosophically and practically. Even though immediate loading has replaced many of the early submerged healing protocols as a state of the science procedure, it is still sometimes difficult to embrace a system that does not require an abutment connection with the inherent flexibility in restoration construction this approach allows. The trade off for abutment versatility is the logistic benefit of a significantly reduced need for reusable and dedicated components
FIGURE 22. Narrow spaces such as these lateral incisor sites are often difficult to restore with standard size implants.
FIGURE 24. This premolar space exhibits good bone availability with a less scalloped residual hard tissue anatomy than is found in anterior regions.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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PAREL AND SCHOW
FIGURE 25. The posterior implant has a preformed coronal extension and margin configuration that simplifies impressions and crown construction. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
FIGURE 28. Radiographic view of the permanently cemented premolar final restoration. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
for the Direct implant. No drivers of any kind are needed because there are no connecting parts, and no inventory of various abutment sizes and collar widths needs to be stocked and replenished as these implants are restored. Coupled with the simplicity of a flapless approach and the relative ease of provisionalization, this concept creates a new level of consideration for the implant selection process.
Conclusion
FIGURE 26. The healed implant shows the level of tissue health attained after 3 months of healing with continuous provisionalization. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
A new 1-piece implant has been used with immediate loading in both anterior and posterior single tooth sites with a high level of early implant success. While these results are promising and the simplified
Table 1. ANTERIOR
Maxilla Mandible
SINGLE TOOTH
Central
Lateral
Cuspid
Total
Failure
6 0
18 (1)* 0
4 1
28 1
1 0
Healed sites, 24; extraction sites, 5. Data from October 2003. *Failure site. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Table 2. POSTERIOR
FIGURE 27. The final crown has been made without further refinement of the margins, and has a gradual subgingival emergence profile circumferentially. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Maxilla Mandible
SINGLE TOOTH
Premolar
Molar
Total
Failure
14 1
0 1
14 2
0 0
All healed sites. Data from August, 2003. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
10 flapless approach is appealing, longer term observation of tissue response will be necessary before a standardized protocol can be developed. Applications in the esthetic zone are especially critical for implant positioning to facilitate crown construction, and future modifications in coronal surface design may be necessary to insure consistent results.
References 1. Babbush CA: Titanium plasma spray screw implant system for reconstruction of the edentulous mandible. Dent Clin North Am 30:117, 1986 2. Ledermann PD: Sechsjaehige klinische Erfahrung mit dem titanplasmabeschichteten ITI-Schraubenimplantat in der Regio Interforaminalis des Unterkiefers. Schweiz Monatsschr Zahnmed 93:1080, 1983 3. Froum SJ, Emtiaz S, Bloom M, et al: The use of transitional implants for immediate fixed temporary prostheses in cases of implant restorations. Pract Periodont Aesthet Dent 10:737, 1998 4. Zubery Y, Bichacho N, Moses O, et al: Immediate loading of modul transitional implants: A historic and histomorphometric study in dogs. Int J Periodont Restor Dent 19:343, 1999 5. Petrungaro P: Fixed temporization and bone augmented ridge stabilization with transitional implants. Pract Periodont Aesthet Dent 9:1071, 1997 6. Simon H: Use of transitional implants to support a surgical guide: Enhancing the accuracy of implant placement. J Prosthet Dent 87:229, 2002 7. Froum S, Simon H, Sang-Choon C, et al: Histologic evaluation of bone-implant contact of immediately loaded transitional implants after 6 to 27 months. Int J Oral Maxillofac Implants 20:54, 2005 8. Schupbach P, Glauser R, Rocci A, et al: The human boneoxidized titanium implant interface: A light microscopic, scanning electron microscopic, back-scaiter scanning electron microscopic, and energy-dispersive x-ray study of clinically retrieved dental implants. Clin Implant Dent Relat Res 7:36, 2005 (suppl 1) 9. Glauser R, Schupbach P, Gottlow J, et al: Periimplant soft tissue barrier of experimental one-piece mini-implants with different surface topography in humans: A light-microscopic overview and histometric analysis. Clin Implants Dent Rel Res 7:44, 2005 (suppl 1) 10. Grunder U: Stability of the mucosal topography around singletooth implants and adjacent teeth. Int J Periodontics Restorative Dent 20:11, 2000 11. Bengazi F, Wennstrom JW, Lekholm U: Recession of the soft tissue margin at oral implants. Clin Oral Implants Res 7:303, 1996
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES 12. Small PN, Tarnow DP: Gingival recession around implants: A 1-year longitudinal prospective study. Int J Oral Maxillofac Implants 15:527, 2000 13. Kokich V, Spear F, Matthews D: Form and function as a team approach. Academy of Osseointegration 20th Annual Meeting, Orlando, FL, March 10-12, 2005 14. Petrungaro P: Immediate restoration of implants using a flapless approach to preserve interdental contours. Pract Proced Aesthet Dent 17:151, 2005 15. Becker W, Goldstein M, Becker B, Sennerby L: Minimally invasive flapless implant surgery: A prospective multi-center study. Clin Implant Dent Rel Res 7:21, 2005 (suppl 1) 16. Rocci A, Martignoni M, Gottlow J: Immediate loading in the maxilla using flapless surgery, implants placed in predetermined positions, and prefabricated provisional restorations: A retrospective 3-year clinical study. Clin Implant Dent Relat Res 2003;5:29 (suppl 1) 17. Kan JY, Rungcharassaeng K, Ojano M, et al: Flapless anterior implant surgery: A surgical and prosthodontic rationale. Pract Periodontics Aesthet Dent 12:467, 2000 18. Campelo LD, Camara JR: Flapless implant surgery: A 10-year clinical retrospective analysis. Int J Oral Maxillofac Implants 17:271, 2002 19. Paolantonio M, Dolci M, Scarano A, et al: Immediate implantation in fresh extraction sockets. A controlled clinical and histological study in man. J Periodontol 72:1560, 2001 20. Landsberg CJ: Socket seal surgery combined with immediate implant placement: A novel approach for single-tooth replacement. Int J Periodont Restor Dent 17:140, 1997 21. Covani U, Barone A, Cornelini R, et al: Soft tissue healing around implants immediately after tooth extraction without incision: A clinical report. Int J Oral Maxillofac Implants 19: 549, 2004 22. Schwartz-Arad D, Chaushu G: Immediate implant placement: A procedure without incisions. J Periodontal 69:743, 1998 23. Sclar AG: Guidelines for flapless surgery. Academy of Osseointegration 20th Annual Meeting, Orlando, FL, March 10-12, 2005 24. Wilson TG Jr, Schenk R, Buser D, et al: Implants placed in immediate extraction sites: A report of histologic and histometric analyses of human biopsies. Int J Oral Maxillofac Implants 48:1153, 1998 25. Cornelini R: Immediate transmucosal implant placement: A report of 2 cases. Int J Periodont Restor Dent 20:199, 2000 26. Wilson TG Jr, Carnio J, Schenk R, et al: Immediate implants covered with connective tissue membranes: Human biopsies. J Periodontal 74:402, 2003 27. Kan JY, Rungcharassaeng K, Umezu K, et al: Dimensions of peri-implant mucosa: An evaluation of maxillary anterior single implants in humans. J Periodontal 74:557, 2003 28. Kois JC: Predictable single tooth peri-implant esthetics: Five diagnostic keys. Compend Contin Educ Dent 22:199, 2001
Early Clinical Experience With a New One-Piece Implant System in Single Tooth Sites Stephen M. Parel, DDS,* and Sterling R. Schow, DMD† Purpose: To evaluate the clinical efficacy of a new 1-piece implant in single tooth sites. Materials and Methods: Early clinical results were evaluated through observation and collection of
survival data for 45 1-piece Direct implants (Nobel Biocare, Yorba Linda, CA). Patients ranged in age from 19 to 54 years, of which 23 were women and 12 were men. Both anterior and posterior single tooth defects were treated, with the majority being in the maxillary anterior zone. Five of the 45 implants placed were in immediate extraction sites. Observation periods ranged from 2.5 to 32 months. Results: One implant failure was detected over the observation period. It occurred in a maxillary lateral incisor site, and was placed and immediately loaded after tooth extraction. The overall success rate was 97.8%. Conclusion: Within the limited parameters of this study, it can be concluded that the 1-piece implant design can be used effectively as a basis for restoring single tooth defects. Longer observation periods, more detailed soft tissue analysis, and larger numbers of implants in varied arch sites will be required to establish definitive protocols for the use of this implant. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:2-10, 2005, Suppl 2 While 1-piece implants are not new to implant dentistry, recent variations from these early designs have created a renewed interest in the unibody concept for both provisional restoration support and permanent application.1-7 The implant evaluated in this report was designed to be used with a flapless approach and has a unique surface application not previously seen in existing 1- or 2-piece designs.
cations have been challenged as 2-piece designs due to strength of components when the diameter approaches the 3 mm level. Either the abutment screw is too small to be sufficiently load-bearing, or the space required for a larger abutment screw will leave the internal side walls of the implant insufficiently thick. Both of these concerns are overcome by a 1-piece design. Another unique feature of this implant is the creation of a rough surface through the soft tissue space as a means of encouraging soft tissue integration and biologic seal. While the long term effects of this design on tissue health are not yet known, initial investigations would support the efficacy of this concept.8,9
Design Features The need for small diameter implants presents on occasion in narrow, single tooth spaces such as maxillary lateral incisors or mandibular incisors. Some previously available narrow implants for these appli-
Materials and Methods
Received from Baylor College of Dentistry - Texas A & M University Health Science Center, Dallas, TX *Professor and Director, Center for Maxillofacial Prosthodontics. †Professor and Director of Residency Training, Department of Oral & Maxillofacial Surgery and Pharmacology. Address correspondence and reprint requests to Dr Parel: Baylor College of Dentistry, 3302 Gaston Ave, Dallas, TX 75246; e-mail: [email protected]
Forty-five single tooth sites were treated with a new 1-piece implant, The Nobel Direct (Nobel Biocare, Yorba Linda, CA), using a flapless surgical approach. The patient ages ranged from 19 to 54 years, with 23 female and 12 male participants. Six patients had more than 1 implant placed, with all sites being isolated and bordered by natural dentition. The overall treatment period ranged from 2.5 to 32 months, with a mean observation period of 14 months.
© 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/6309-0202$30.00/0 doi:10.1016/j.joms.2005.05.150
2
PAREL AND SCHOW
FIGURE 1. This healed site for a maxillary lateral incisor has good bone width, existing interdental papilla position, and normal bone height on adjacent tooth surfaces (not shown radiographically). Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Anterior Dentition For single tooth application, fixture location components have been designed that may eliminate the need for conventional prefabricated surgical guides. A slide-over guide sleeve can be used with the initial 2 mm twist drill osteotomy to help visualize the position of the eventual implant coronal extension (Figs 1-3). A tissue punch guide can then be placed into the 2 mm osteotomy to serve as an axial guide for the circular tissue trephine (Figs 4-6). Nearly complete soft tissue removal is essentially accomplished using this rotary instrument to the crest of the alveolar bone. A sharp curette or spoon is used to remove the tissue remnants at the crestal surface that were not severed by the handpiece instrument. One of the significant benefits of this particular flapless approach is the creation of the initial free gingival margin at a
3
FIGURE 3. The surgical guide slips over the 2 mm twist drill and is used as a visual reference as the initial osteotomy is performed. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
low level relative to the adjacent marginal gingiva. This will allow vertical room for manipulation of the semi-lunar soft tissue during provisionalization, thus minimizing the possibility of creating an initial margin position at an undesirable apical level. With time and healing, this margin will generally migrate apically approximately 1 mm as a natural occurrence.10-12 Using this tissue manipulation concept, this apical migration will generally not present an esthetic compromise because the starting position of the marginal gingival was created coronally by design. Completion of the osteotomy site is accomplished using the drill sequence appropriate for the size implant anticipated in this site (Figs 7, 8). The implant taper corresponds to the Replace Select product line (Nobel Biocare), so the existing Select drill set can be used for the Direct implant as well.
FIGURE 2. The surgical guides represent the basic shape of the various implant coronal surfaces and have a hollow central core.
FIGURE 4. Tissue punch guides are color coded to correspond with implant sizes, with an extension apically that anchors in the 2 mm osteotomy.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
4
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 5. In position, the punch guide allows the tissue removal to be consistent with the long axis of implant placement.
FIGURE 7. The initial 2 mm osteotomy is expanded to a width appropriate for the diameter of the implant to be placed.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Implant position is important in either arch, and is especially critical in the esthetic zone. For long term tissue maintenance, every attempt should be made to keep the fixture long axis slightly to the palatal aspect of the edentulous space and to avoid a facial tilt or flare to the implant.13 This concept applies to an even greater degree in immediate extraction/immediate load cases, where the tendency is to follow the apical socket contour, which may direct the implant to a less desirable facial orientation. Implant placement is completed using machine torque initially and hand wrench final torque as necessary to the eventual desired position (Fig 9). Stargrip drivers engage the coronal internal surface for all but the 3 mm design, and are used exclusively to deliver these implants. Because the coronal diameter of the 3 mm implant is too narrow to accommodate an internal drive connection, an external socket
driver that engages the axial bevel on the implant head is used as the fixture mount for this series. Upon complete seating of the implant and verification of an acceptable initial stability, the occlusal clearance is evaluated in centric position. Gross reduction of the occlusal surface using multi-fluted carbide burs is the only recommended intervention at this stage, which makes space for the provisional restoration as needed (Fig 10). Modification of the axial surfaces for contour or margin definition is delayed until the implant has completely integrated. The provisional restorations can be completed most practically as a chairside procedure using prefabricated shell crowns or the laboratory produced equivalent. It is important that the relining procedure involve multiple “on-off” maneuvers as the resin is setting to avoid entrapment of cured resin subgingivally. Once the final set has been achieved, the provisional crown should seat and unseat without exces-
FIGURE 6. The rotary trephine creates a clean soft tissue opening, but will generally require subsurface curettage to expose a circumferential bone surface.
FIGURE 8. The 1-piece Direct implant (first generation) has a tapered profile and a rough surface through the soft tissue zone.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 9. Implant placement (with the exception of the 3 mm size) is completed to final position using a star-grip driver and mechanical or hand torque as required.
FIGURE 11. The provisional shell crown is initially indexed with resin intraorally, and is finished on a similarly reduced analog implant to a desired uniform margin depth and contour.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
sive vertical force being required. Final margin position can be completed on an analog implant, with subgingival extension ideally approximately 1 to 1 1/2 mm circumferentially (Figs 11, 12). Provisional restoration occlusal contacts should be grossly absent in centric position and all excursive movements, even if an under-extended incisal edge needs to be created (Fig 13). Embrasure contacts should also be light. A provisional cement is used for luting, and crown removal, unless absolutely necessary, is avoided for at least 3 months. Patients are advised to avoid this site when chewing, and to stay on a soft diet for at least 2 weeks. Following successful integration, usually at 3 to 4 months, the provisional is removed and sulcus depth is evaluated (Fig 14). On the larger diameter implants, 4.3 and 5.0 mm, it is possible to create a facial finish
line subgingivally using specifically designed carbide burs and copious irrigation (Figs 15, 16). It is impossible to avoid tissue damage during facial recontouring, so the provisional should be relined to the new finish line and recemented for at least 3 weeks for tissue recovery (Fig 17). Experience to date has shown no adverse residual effects from the tissue trauma caused by preparation of the coronal extension. For the smaller diameter implants (3.0 or 3.5 mm), any necessary sulcus extension needed for profile is accomplished by extending the provisional margin and waiting several weeks for tissue resolution before impressions. Handpiece reduction on these smaller implant abutment axial surfaces is not recommended. Whether retraction is needed for final impressions is determined by the health and stability of the tissue at the follow-up appointment. Because of the more
FIGURE 10. Initial reduction is for occlusal clearance only using specifically designed multi-fluted carbide burs. Axial reduction is not recommended at this stage.
FIGURE 12. The initial restoration is cemented with a provisional cement of choice.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 13. Occlusal contact is grossly absent in centric position and all excursive movements. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
rigid tissue integration commonly seen against this rough surface, it will feel like more pressure than average is needed to place retraction cord. Fortunately, any disruption of the hemi-desmesomal attachment recovers without complication following cord removal (Fig 18). The definitive crown is fabricated using conventional means, usually with a porcelain-fused-to-metal approach (Fig 19). Final cementation is performed conventionally using a long term cement of choice (Figs 20, 21). The same approach for final crown construction is used for the 3.0 mm implant option with the exception of the need for margin preparation as noted above (Figs 22, 23).
Posterior Applications Specific design changes with a flat, preformed margin make this implant very effective in the premolar
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 15. Narrow, rounded carbide finishing burs are used to create a finish line subgingivally, generally on the facial-axial surfaces only. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
and molar regions (Figs 24, 25). It is possible, in fact, to complete a single tooth restoration without the need for a driver or handpiece for metal reduction when using this implant option. This technique requires that the implant be placed apically enough initially to have sufficient clearance for provisionalization as previously described, and to allow placement of the margins uniformly subgingivally (Fig 26). The preformed margin is not scalloped, so use in the esthetic zone is not advised. However, in posterior areas with flatter embrasure contour, this horizontal margin design is acceptable, and facilitates a simplified approach to impressioning and final restoration with improved emergence profile (Figs 27, 28).
Discussion Early clinical experience with this implant has been encouraging (97.8% overall) with regard to implant
FIGURE 14. After 3 to 4 months of healing, the implant is evaluated for integration. Note the positive changes in soft tissue volume interproximally, and the apical migration of the free gingival margin.
FIGURE 16. The coronal surface has been modified with a subgingival finish line on the facial aspect.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
PAREL AND SCHOW
FIGURE 17. Following margin preparation, reprovisionalization with a relined temporary is usually necessary for tissue resolution. An additional healing period of 3 to 4 weeks is recommended. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
success (Tables 1, 2). It is important, however, to consider the implications of a flapless approach, especially in the esthetic zone, when evaluating these results. A flapless approach has been shown to have inherent benefits in soft tissue preservation, particularly for the interdental papilla, in a variety of applications.14,15 It has also been documented to be a safe procedure in terms of implant success, with percentages equivalent to healed site and delayed loading protocols.15-22 There is, however, no data that would support a predictable esthetic outcome on a consistent basis simply by using a flapless technique.10,16,17,23 Inability to directly visualize the path of the osteotomy and eventual implant placement position may also result in undetected fenestration or minor dehiscence apically. While this is not necessarily a precursor to implant failure, it can generally be
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FIGURE 19. The completed crown has been constructed with a ceramic facial margin to maximize cervical translucency. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
minimized or avoided as experience increases with this technique.24 It is of interest to note that the only failure resulted from implant placement in an extraction site. The efficacy of a flapless approach in many of these situations will be dictated by the presence of a contiguous buccal plate at a reasonable distance from the free gingival margin (4 mm) and an implant bone-gap of less than 2 mm.19,25-27 Because there is insufficient evidence to predict an esthetic result at the extremes of these parameters, it is currently recommended that a socket preservation procedure be performed with delayed implant placement until sufficient data are available to support an alternative procedure. Without the flexibility of an interchangeable abutment, the initial positioning of this implant in the esthetic zone becomes even more critical with a 1-piece design. If space is not created facially for restorative materials to emerge with natural contours,
FIGURE 18. The final impression records the sulcus depth and margin preparation, usually without the need for extensive retraction.
FIGURE 20. The clinical result at 1 month following crown delivery.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 21. Radiographic view of the integrated implant and resultant bone position 1 year from date of placement. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
there may be a tendency for the marginal gingival to “creep” apically, resulting in a longer than desired clinical crown appearance.13 Thus, experience and expertise in sagittal and vertical implant positioning will play a role in this aspect of the surgical learning curve. It is important to also consider patient selection with regard to gingival biotype profile.28 Because of the highly adherent nature of the soft tissue to the extended implant rough surface, there may be a greater tendency for eventual gingival discoloration in patients with thin overlying keratinized epithelium. In diagnosing candidates preoperatively for this procedure, it may be necessary to incorporate a “roll-over” or free subepithelial connective tissue graft proce-
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES
FIGURE 23. Radiographic position of a restored 3 mm 1-piece implant illustrates the space available for adjacent bone structure with minimal papilla encroachment. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
dure into the treatment plan if adequate thickness of overlying gingiva is not present. The 1-piece permanent implant represents a significant departure from the time-tested 2-piece approach both philosophically and practically. Even though immediate loading has replaced many of the early submerged healing protocols as a state of the science procedure, it is still sometimes difficult to embrace a system that does not require an abutment connection with the inherent flexibility in restoration construction this approach allows. The trade off for abutment versatility is the logistic benefit of a significantly reduced need for reusable and dedicated components
FIGURE 22. Narrow spaces such as these lateral incisor sites are often difficult to restore with standard size implants.
FIGURE 24. This premolar space exhibits good bone availability with a less scalloped residual hard tissue anatomy than is found in anterior regions.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
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FIGURE 25. The posterior implant has a preformed coronal extension and margin configuration that simplifies impressions and crown construction. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
FIGURE 28. Radiographic view of the permanently cemented premolar final restoration. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
for the Direct implant. No drivers of any kind are needed because there are no connecting parts, and no inventory of various abutment sizes and collar widths needs to be stocked and replenished as these implants are restored. Coupled with the simplicity of a flapless approach and the relative ease of provisionalization, this concept creates a new level of consideration for the implant selection process.
Conclusion
FIGURE 26. The healed implant shows the level of tissue health attained after 3 months of healing with continuous provisionalization. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
A new 1-piece implant has been used with immediate loading in both anterior and posterior single tooth sites with a high level of early implant success. While these results are promising and the simplified
Table 1. ANTERIOR
Maxilla Mandible
SINGLE TOOTH
Central
Lateral
Cuspid
Total
Failure
6 0
18 (1)* 0
4 1
28 1
1 0
Healed sites, 24; extraction sites, 5. Data from October 2003. *Failure site. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Table 2. POSTERIOR
FIGURE 27. The final crown has been made without further refinement of the margins, and has a gradual subgingival emergence profile circumferentially. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
Maxilla Mandible
SINGLE TOOTH
Premolar
Molar
Total
Failure
14 1
0 1
14 2
0 0
All healed sites. Data from August, 2003. Parel and Schow. One-Piece Implant System in Single Tooth Sites. J Oral Maxillofac Surg 2005.
10 flapless approach is appealing, longer term observation of tissue response will be necessary before a standardized protocol can be developed. Applications in the esthetic zone are especially critical for implant positioning to facilitate crown construction, and future modifications in coronal surface design may be necessary to insure consistent results.
References 1. Babbush CA: Titanium plasma spray screw implant system for reconstruction of the edentulous mandible. Dent Clin North Am 30:117, 1986 2. Ledermann PD: Sechsjaehige klinische Erfahrung mit dem titanplasmabeschichteten ITI-Schraubenimplantat in der Regio Interforaminalis des Unterkiefers. Schweiz Monatsschr Zahnmed 93:1080, 1983 3. Froum SJ, Emtiaz S, Bloom M, et al: The use of transitional implants for immediate fixed temporary prostheses in cases of implant restorations. Pract Periodont Aesthet Dent 10:737, 1998 4. Zubery Y, Bichacho N, Moses O, et al: Immediate loading of modul transitional implants: A historic and histomorphometric study in dogs. Int J Periodont Restor Dent 19:343, 1999 5. Petrungaro P: Fixed temporization and bone augmented ridge stabilization with transitional implants. Pract Periodont Aesthet Dent 9:1071, 1997 6. Simon H: Use of transitional implants to support a surgical guide: Enhancing the accuracy of implant placement. J Prosthet Dent 87:229, 2002 7. Froum S, Simon H, Sang-Choon C, et al: Histologic evaluation of bone-implant contact of immediately loaded transitional implants after 6 to 27 months. Int J Oral Maxillofac Implants 20:54, 2005 8. Schupbach P, Glauser R, Rocci A, et al: The human boneoxidized titanium implant interface: A light microscopic, scanning electron microscopic, back-scaiter scanning electron microscopic, and energy-dispersive x-ray study of clinically retrieved dental implants. Clin Implant Dent Relat Res 7:36, 2005 (suppl 1) 9. Glauser R, Schupbach P, Gottlow J, et al: Periimplant soft tissue barrier of experimental one-piece mini-implants with different surface topography in humans: A light-microscopic overview and histometric analysis. Clin Implants Dent Rel Res 7:44, 2005 (suppl 1) 10. Grunder U: Stability of the mucosal topography around singletooth implants and adjacent teeth. Int J Periodontics Restorative Dent 20:11, 2000 11. Bengazi F, Wennstrom JW, Lekholm U: Recession of the soft tissue margin at oral implants. Clin Oral Implants Res 7:303, 1996
ONE-PIECE IMPLANT SYSTEM IN SINGLE TOOTH SITES 12. Small PN, Tarnow DP: Gingival recession around implants: A 1-year longitudinal prospective study. Int J Oral Maxillofac Implants 15:527, 2000 13. Kokich V, Spear F, Matthews D: Form and function as a team approach. Academy of Osseointegration 20th Annual Meeting, Orlando, FL, March 10-12, 2005 14. Petrungaro P: Immediate restoration of implants using a flapless approach to preserve interdental contours. Pract Proced Aesthet Dent 17:151, 2005 15. Becker W, Goldstein M, Becker B, Sennerby L: Minimally invasive flapless implant surgery: A prospective multi-center study. Clin Implant Dent Rel Res 7:21, 2005 (suppl 1) 16. Rocci A, Martignoni M, Gottlow J: Immediate loading in the maxilla using flapless surgery, implants placed in predetermined positions, and prefabricated provisional restorations: A retrospective 3-year clinical study. Clin Implant Dent Relat Res 2003;5:29 (suppl 1) 17. Kan JY, Rungcharassaeng K, Ojano M, et al: Flapless anterior implant surgery: A surgical and prosthodontic rationale. Pract Periodontics Aesthet Dent 12:467, 2000 18. Campelo LD, Camara JR: Flapless implant surgery: A 10-year clinical retrospective analysis. Int J Oral Maxillofac Implants 17:271, 2002 19. Paolantonio M, Dolci M, Scarano A, et al: Immediate implantation in fresh extraction sockets. A controlled clinical and histological study in man. J Periodontol 72:1560, 2001 20. Landsberg CJ: Socket seal surgery combined with immediate implant placement: A novel approach for single-tooth replacement. Int J Periodont Restor Dent 17:140, 1997 21. Covani U, Barone A, Cornelini R, et al: Soft tissue healing around implants immediately after tooth extraction without incision: A clinical report. Int J Oral Maxillofac Implants 19: 549, 2004 22. Schwartz-Arad D, Chaushu G: Immediate implant placement: A procedure without incisions. J Periodontal 69:743, 1998 23. Sclar AG: Guidelines for flapless surgery. Academy of Osseointegration 20th Annual Meeting, Orlando, FL, March 10-12, 2005 24. Wilson TG Jr, Schenk R, Buser D, et al: Implants placed in immediate extraction sites: A report of histologic and histometric analyses of human biopsies. Int J Oral Maxillofac Implants 48:1153, 1998 25. Cornelini R: Immediate transmucosal implant placement: A report of 2 cases. Int J Periodont Restor Dent 20:199, 2000 26. Wilson TG Jr, Carnio J, Schenk R, et al: Immediate implants covered with connective tissue membranes: Human biopsies. J Periodontal 74:402, 2003 27. Kan JY, Rungcharassaeng K, Umezu K, et al: Dimensions of peri-implant mucosa: An evaluation of maxillary anterior single implants in humans. J Periodontal 74:557, 2003 28. Kois JC: Predictable single tooth peri-implant esthetics: Five diagnostic keys. Compend Contin Educ Dent 22:199, 2001