Effects of a new implant abutment design on peri-implant soft tissues.

The purpose of this study was to assess the effects of a modified implant abutment design on peri-implant soft and hard tissues in dogs. Three months after extraction of mandibular premolar teeth, 3 dental implants were placed in each side of the jaw using a 1-stage approach. Implants on one side of the mandible received standard abutments (control), and implants on the contralateral side received modified, patented, grooved abutments (test). Two months after implant placement, animals were euthanized and specimens were prepared for histologic and histomorphometric assessment. The linear distance (in micrometers) was measured from the implant shoulder (IS) to the following landmarks: gingival margin (GM; distance IS-GM), most apical position of the junctional epithelium (JE; distance IS-JE), and bone crest (BC; distance IS-BC). Percent of bone-to-implant contact was also measured. Histologic assessment revealed that all implants were osseointegrated and that interimplant gingival fibers between test abutments appeared to be more numerous and organized than control abutments. The IS-GM and IS-JE distances in test implants were greater than the corresponding distances in control implants (P = .024 and P = .015, respectively), whereas crestal bone loss (IS-BC) was greater for control implants than test implants (P = .037). There were no differences between control and test implants in bone-to-implant contact (P = .69), which averaged close to 50%. These results suggest that the modified groove design incorporated in standard abutments confers both soft and hard tissue benefits.

A pilot study to assess the performance of a partially threaded sintered porous-surfaced dental implant in the dog mandible.

PURPOSE: The purpose of this study was to compare patterns of crestal bone remodeling with 2 sintered porous-surfaced dental implant designs during a 14-month functional period. MATERIALS AND METHODS: Two root-form press-fit dental implants were evaluated in healed extraction sites in dog mandibles. The standard (control) design was a press-fit implant with a 2-mm machined collar; the remainder of the implant had a sintered porous surface. The test or "hybrid" design had 3 coronal machined threads instead of a machined collar; the remainder of the implant had a sintered porous surface. RESULTS: Standardized radiographs indicated significantly less crestal bone loss (0.82 to 0.93 mm versus 1.45 to 1.5 mm) with the hybrid design and a slower approach toward an apparent steady state (12 to 14 months for the hybrid versus 7 months for the standard design). Morphometric assessment of back-scattered scanning electron micrographs confirmed that crestal bone loss was significantly less for the hybrid design on all but the lingual implant aspect. CONCLUSION: The addition of coronal threads to an implant relying on a sintered porous surface geometry for its long-term osseointegration reduced the extent of crestal bone loss compared to a machined collar region.

Evaluation of a variable-thread tapered implant in extraction sites with immediate temporization: a 3-year multicenter clinical study.

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.

Two-year evaluation of a variable-thread tapered implant in extraction sites with immediate temporization: a multicenter clinical trial.

PURPOSE: The purpose of this clinical trial was to evaluate the survival rate, bone remodeling, and soft tissue health surrounding variable-thread tapered implants placed in fresh extraction sites and loaded immediately. MATERIALS AND 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. Definitive prostheses were placed within the first year. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, and 24 months. Assessments of implant stability, Papilla Index, plaque, peri-implant mucosa, and marginal bone levels were performed at the respective visits. RESULTS: Fifty-five patients were treated and were restored with 58 single crowns and 1 two-unit fixed partial prosthesis. The cumulative survival rate was 98.3% after 2 years. One implant failed prior to 3 months. The mean marginal bone remodeling from implant insertion to 1 year was -0.22 ± 1.30 mm (n = 41), followed by an average bone gain of 0.12 ± 0.77 mm (n = 33) between 12 and 24 months. Mean marginal bone remodeling was -0.10 ± 1.38 mm (n = 35) from implant insertion to 2 years. Papilla size increased significantly over the 2-year study period. Patient assessments of function, esthetics, and self-esteem also showed significant improvement. CONCLUSION: The 24-month results indicate that the variable-thread tapered implant can be used safely and effectively under demanding conditions as an immediate postextraction tooth replacement.