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Bone and Soft Tissue Response in Bone-Level Implants Restored with Platform Switching: A 5-Year Clinical Prospective Study.

PURPOSE
The aim of this prospective study was to evaluate radiographic levels of peri-implant bone crest as well as soft tissue response, papilla height, and buccal mucosa recession, in bone-level implants restored with platform switching after 1-year and 5-year follow-ups.


MATERIALS AND METHODS
This prospective study called for the placement of 59 implants to obtain a target of 90% power. To compensate for possible dropouts, the sample size was adjusted to 67 implants. To assess marginal bone level changes, periapical radiographs were taken at baseline, 1 year, and 5 years after the definitive restorations. Peri-implant soft tissue modifications were evaluated by performing a photographic sequence at 15 days, 1 year, and 5 years after implant restoration. Parameters measured were: (1) distance from the tip of the papilla to the contact point and (2) apicocoronal crown length.


RESULTS
A one-way analysis of variance (ANOVA rank test) was used to compare quantitative data among the three time points studied. Mean marginal bone level changes were as follows: -0.06 ± 0.32 mm from baseline to 1 year, -0.23 ± 0.38 mm from 1 to 5 years, and -0.28 ± 0.45 mm from baseline to 5 years. In bone-level outcomes, no statistically significant differences were found between baseline and 1 year, while the mean differences between 1 and 5 years and baseline and 5 years showed statistically significant differences. In the soft tissue analysis, the distance from the tip of the papilla to the contact point showed the following values: baseline, 2.08 mm; 1 year, 1.54 mm; 5 years, 1.31 mm. No statistically significant differences were found between baseline and 1 year, whereas statistically significant differences between 1 and 5 years and baseline and 5 years were found. Apicocoronal crown length measurements showed the following values: baseline, 9.44 mm; 1 year, 9.28 mm; 5 years, 9.81 mm. No significant differences were found between times studied.


CONCLUSION
This prospective clinical study of 67 bone-level implants restored according to the platform-switching concept reported that radiographic levels of peri-implant bone crest were statistically significant between 1 and 5 years and baseline and 5 years. For the soft tissue response, the greatest reduction in the distance from the papilla to the contact point from 1 to 5 years and baseline to 5 years was observed. No significant differences were shown in the buccal margin.