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

Abstract

Background: Implant 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 >30º in comparison to those with ≤30º in terms of changes in peri-implant marginal bone level, periodontal parameters, and prevalence rate of peri-implantitis.

Methods: Electronic databases were searched to identify observational studies that compared implant restorations with an emergence angle of >30º to those with ≤30º. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool.

Results: Four 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 >30º, while the remaining implants had restorative emergence angle of ≤30º. The follow-up time varied between 3.8 and 10.9 years. Implant restorations with an emergence angle of ≤30º were associated with less changes in peri-implant marginal bone level compared to those with emergence angle of >30º. 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 ≤30º. 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).

Conclusions: Within the limitation of this review, implant restorations with an emergence angles of >30º or ≤30º seem to have no significant influence on peri-implant marginal bone level. Platform-matched implants with an emergence angle of ≤30º may have positive effects on the peri-implant marginal bone level changes, but the evidence support is of low to moderate certainty.