Evaluation of a Variable-Thread Tapered Implant in Extraction Sites With Immediate Temporization: A 3-Year Multicenter Clinical Study

• Autores: Martin L. Kolinski, James E. Cherry, Bradley S. McAllister, Kenneth D. Parrish
• Localización: Journal of periodontology, ISSN 0022-3492, Nº. 3, 2014, págs. 386-394
• Idioma: inglés
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• Resumen

  • Background: The purpose of this clinical study is to evaluate the radiographic bone remodeling, survival rate, and soft tissue health surrounding a variable-thread tapered implant immediately placed in extraction sites.

    Methods: Sixty implants were placed in 55 patients at six centers according to a predetermined protocol. All implants were placed in extraction sockets and were subjected to immediate temporization and function. Definitive prostheses (58 single crowns and one two-unit fixed bridge) were placed within the first year. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, 24, and 36 months. Measurements of implant stability, papilla index, plaque, peri-implant mucosa, and marginal bone levels were recorded at each visit.

    Results: Thirty-five implants were evaluated at both implant insertion and 3-year follow-up. Bone levels were observed at 6 months after surgery and yearly intervals thereafter and remained stable throughout the study. There was a slight decrease in mean bone level from -0.68 mm at implant insertion to -0.93 mm at the 6-month recall and then an increase of bone to -0.53 mm from the reference point at the 2-year follow-up (an average increase of 0.15 mm from implant insertion). Bone levels remained steady between the 2-year recall and the 3-year recall. Papilla scores increased significantly (P <0.001; Wilcoxon signed-rank test) from insertion to the 3-year follow-up, with most of the increase occurring during the first year. Patient assessments of function, esthetics, feel of implant, speech, and self-esteem also showed significant improvement over the course of the study.

    Conclusions: The results, over 36 months, indicate that the variable-thread tapered implant can be used safely and effectively under demanding conditions as an immediate postextraction tooth replacement. Bone remodeling remained stable with a slight increase, and patients expressed high levels of satisfaction with the restorative results over the course of the study.

    Immediate placement of implants after extraction with immediate temporization can be both desirable and predictable in appropriate cases. Numerous studies on many different implant designs used with immediate loading have shown success rates of >95%.1-4 These studies all support extraction and immediate placement with immediate temporization or functional loading. Common factors that contribute to the success of implants placed and temporized immediately after extraction include the use of minimally traumatic extraction techniques, a roughened surface implant,5-7 good initial fixation,8 loads that are not excessive,9,10 and sufficient bone quality and volume.11 Quantity and quality of the receptor bone can prove to be misleading and unpredictable, even in cases that look to be straightforward. Cone beam computed tomography radiographs can help with the preoperative evaluation of bone quantity, but at times the quality can be difficult to gauge until the initial osteotomy is started. Turkyilmaz et al.11 concluded that bone volume is assessable but quality often is not. Poor receptor bone can make it difficult to gain adequate initial fixation to anchor an implant with sufficient stability to support an immediate temporary restoration.

    Other studies have shown the effect of various implant designs on the load to bone.12-14 Some features aiding in long-term bone and soft tissue stability on immediate implants include roughened surfaces, tapered designs, and platform-shifting restorative connections. These features are all present in the design of the implant used in this study.# When the presurgery goal is to provide an immediate temporary restoration, initial stability is essential. Design features to aid in providing good initial stability are also important. This variable-thread implant has design features to aid in initial implant stability even in poor-quality bone. The implant has a unique thread design that allows for cutting of the bone as it is threaded into place. This cutting feature permits the implant to be driven into place with a narrower initial osteotomy and to cut through brittle bone, reducing the incidence of alveolar fracture, which can occur with other tapered implant designs. The thread design also lets the surgeon redirect the implant, should the initial placement be determined to be less than ideal. These features can provide for immediate function even in cases with less than ideal receptor bone.

    This paper is an evaluation of the radiographic bone remodeling and soft tissue health (papilla, plaque, and bleeding on probing [BOP]) of this variable-thread implant design at 3 years after initial implant placement and immediate temporization. The results presented here follow an earlier paper by McAllister et al.15 with 2-year results, with the aim of providing the 3-year follow-up data obtained from this multicenter study.