Peri-implant Soft Tissue Healing Around Platform-Switching and Platform-Matching Single Implants

Objectives: Implants with platform-switching design have been demonstrated to reduce marginal bone loss. However, its influence on peri-implant soft tissue healing is not clear. The purpose of this study was to investigate whether dental implant with the platform-switching design would render significant benefits on peri-implant soft tissue healing after implant uncovery.

Methods: Non-smokers demanding two dental implants in different quadrants were recruited in this randomized controlled trial. For each individual, one platform-switching (PS) and one platform-matching (PM) implants were placed with the standard 2-stage protocol. After 2-4 months, all implants were uncovered and connected to the correspondent healing abutments. Probing depth (PD), modified sulcus bleeding index (mSBI), modified plaque index (mPI), and peri-implant crevicular fluid (PICF) were taken at week-1, -2, -4, and -6 post-uncovery. Peri-implant mucosa (1×2×2mm) was harvested around the abutment at uncovery and week-6 post-uncovery. The production of IL-1β, IL-10, osteoprotegerin (OPG), TNF-α and VEGF in PICF were analyzed by ELISA. The gene expressions of CTGF, IL-6, CRP, OPG, RANKL, periostin and peroxidasin were analyzed by qPCR. Paired sample t-test was used for statistic analysis.

Results: 18 subjects (9 males; 51.7±14.9 years) were recruited. Compared to PM, PS showed significant lower PD at week-1 and -2 as well as mSBI at week-1, -4 and -6. Over time, OPG and IL-1β production in PICF were significantly reduced along with the significant increase of RANKL, periostin and peroxidasin gene expressions in peri-implant mucosa within both groups; however, differences between groups were not statistically significant.

Conclusions: Within the limits of this study, implants with PS design rendered significant benefits over PM implants in terms of PD and mSBI reduction during a 6-week healing. However, peri-implant soft tissue response for PM and PS implants appears to be similar during the healing period, especially for cytokine release and gene expressions.