Mucosa Thickness and Peri-implant Crestal Bone Stability: A Clinical and Histologic Prospective Cohort Trial

Purpose: To correlate soft tissue thickness and peri-implant bone remodeling of platform-switching implants. Materials and Methods: This comparative prospective trial evaluated, for up to 3 years after implant loading, the influence of soft tissue thickness on changes in peri-implant marginal hard tissue levels. Any patient who was partially edentate in the mandible and required at least two adjacent implant-supported restorations was recruited at the University of Valencia in Spain. A 3-mm tissue punch biopsy, which corresponded to a diameter slightly smaller than the coronal diameter of the implants, was performed using a circular mucotome. Afterward, implants with a length of 10 to 13 mm and a diameter of 3.8 mm were inserted. Outcome measures were implant and prosthesis survival rates, marginal hard tissue changes, any complications, and results of morphologic and histomorphometric analyses. Correlation between mucosa width components (epithelium, connective tissue, and epithelium and connective tissue) and radiographic bone loss at 1 and 3 years after loading was performed at the patient level. Statistical significance was set at P ≤ .05. Results: A total of 26 samples in 26 patients with 68 implants were analyzed. The specimens were divided into two groups: group 1 (16 patients, 40 implants), with thin mucosa (≤ 2 mm), and group 2 (10 patients, 28 implants), with thick mucosa (> 2 mm). Two dropouts (two specimens) were recorded at the 3-year follow-up. None of the implants or definitive prostheses failed during the healing period, resulting in an overall implant and prosthesis cumulative survival rate of 100%. No major biologic or mechanical complications were recorded. The mean (standard deviation, SD) epithelium thickness was 430.33 (250.21) μm; the mean (SD) connective tissue thickness was 1,324.31 (653.46) μm, and the mean (SD) mucosa thickness was 1,751.29 (759.53) μm. Comparisons of radiographic bone loss between group 1 and group 2 failed to show any statistically significant differences at the 1-year (P = .290) or 3-year (P = .090) follow-up examinations. Conclusion: The initial mucosa thickness surrounding a bone-level platform-switching implant seems not to influence the pattern of physiologic marginal bone loss. Keywords: dental implants, marginal bone loss, mucosa thickness, platform switching