Implant-abutment emergence angle and profile in relation to peri-implantitis: A systematic review.

Statement: The aim of this systematic review is to analyze literature regarding the relationship between the implant-abutment emergence angle (EA) and implant emergence profile (EP) and the prevalence of peri-implantitis.

Methods: PubMed and the Cochrane Library were searched for studies from initiation up to April 2022. Studies describing the EA and EP in association with peri-implantitis were considered eligible for this review and selected for inclusion in this review if implant groups with wide and narrow EA and different EP types were described.

Results: Searches in PubMed and the Cochrane Library led to 1116 unique titles and the inclusion of three studies. These concerned 168-349 implants. Two studies presented the mean prevalence of peri-implantitis which was 16.7% and 24.8% at the implant level. Both studies showed a significant relationship between peri-implantitis in bone-level implant groups with an EA above 30° compared to implants with an EA below 30°. A third study presented marginal bone loss which tended to be smaller when the EA was around 20°-40°. In one of the three included studies, the prevalence of peri-implantitis was significantly higher if implants had a convex EP compared to a concave or straight EP. Another study showed a significantly higher prevalence of peri-implantitis in implants with a convex EP compared to other EP types, if combined with an EA above 30°.

Conclusions: Three eligible studies were found. Reported associations should therefore be considered with caution. Synthesis suggests an association between a larger EA (>30°) and a higher prevalence of peri-implantitis or marginal bone loss compared to a smaller EA (<30°). A convex EP may also be associated with a higher prevalence of peri-implantitis. However, causality remains a question.