Does the platform switching implant affect the crestal bone level? A systematic review and meta-analysis

Objectives: To assess the effects of platform switching in patients restored with implant supported fixed restorations on implant failure and patient satisfaction. Materials and methods: We searched the Cochrane Oral Health Group Trial register (04 February 2017), Cochrane Central Register of Controlled Trials (The Cochrane Library 2017, Issue 02), MEDLINE (January 1966 to 04 February 2017) and the WHO International Clinical Trial Registry Platform (04 February 2017). We hand searched citation lists of relevant publications. We did not apply any language or date restrictions. Randomised controlled trials (RCTs) comparing the effectiveness of platform switching versus platform matching in patients restored with implant supported fixed restorations were included. Two reviewers independently assessed trials for inclusion and risk of bias, extracted data and checked for accuracy. We have expressed results as risk ratio (RR) or mean differences (MD), together with their 95% confidence intervals (CI). The primary outcome measures were implant failure and patient satisfaction. Results: We included 12 studies (513 participants). There was no difference between platform switching and matching after 1-3 years of follow up in implant failures (RR 0.32, 95% CI 0.01 to 7.70; studies = 7) or patient satisfaction (MD 0.13, 95% CI -0.29 to 0.55; participants = 24; studies = 1). Regarding marginal bone loss, when we pooled down the data obtained from six trials, we identified substantial heterogeneity (I2 = 81%) with inconsistency in the direction of effect, which was unexplained by clinical or methodological differences between the studies, and accordingly we did not perform meta-analysis for this outcome. Conclusions: In patients restored with implant supported fixed restorations, there is insufficient evidence to support platform switching or platform matching implant-abutment connection design to improve implant survival and patient satisfaction.