Influence of implant restorative emergence angle and contour on peri-implant marginal bone loss: A systematic review and meta-analysis

BackgroundImplant restorative emergence angle and profile may have a negative impact on peri-implant marginal bone level and may increase the risk of developing peri-implantitis. However, the role of these prosthetic features on peri-implant health is still unclear. The aim of this systematic review and meta-analyses was to evaluate the long-term outcomes of implant restorations with an emergence angle of >30 degrees in comparison to those with <= 30 degrees in terms of changes in peri-implant marginal bone level, periodontal parameters, and prevalence rate of peri-implantitis. MethodsElectronic databases were searched to identify observational studies that compared implant restorations with an emergence angle of >30 degrees to those with <= 30 degrees. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool. ResultsFour studies with 912 dental implants in 397 participants were included in the present review. Of these, 455 implants had restorations with an emergence angle of >30 degrees, while the remaining implants had restorative emergence angle of <= 30 degrees. The follow-up time varied between 3.8 and 10.9 years. Implant restorations with an emergence angle of <= 30 degrees were associated with less changes in peri-implant marginal bone level compared to those with emergence angle of >30 degrees. The difference, however, was not statistically significant (mean difference 0.80; 95% confidence interval (CI) -0.13 to 1.72; p = 0.09). In platform-matched implants, the difference between the two groups was statistically significant in favor of implant restorations with emergence angle of <= 30 degrees. In terms of emergence profile, implant restorations with convex profile had significantly higher rate of peri-implantitis (57.8%) compared to implant restorations with concave or straight profile (21.3%) (risk ratio 2.32; 95% CI 1.12-4.82; p = 0.02). ConclusionsWithin the limitation of this review, implant restorations with an emergence angles of >30 degrees or <= 30 degrees seem to have no significant influence on peri-implant marginal bone level. Platform-matched implants with an emergence angle of <= 30 degrees may have positive effects on the peri-implant marginal bone level changes, but the evidence support is of low to moderate certainty.