Microgap Formation in Conical Implant-Abutment Connections Under Oblique Loading: Influence of Cone Angle Mismatch Through Finite Element Analysis

Objectives: This study evaluated different designs of the conical implant-abutment connection (IAC) and their resistance to microgap formation under oblique loads as specified by the ISO standard for testing dental implants. Also evaluated was the effect of deviations from the ISO specifications on the outcomes. Methods: Finite element analysis was conducted to compare the microgap formation and stress distribution among three conical IAC designs (A, B, and C) in two loading configurations: one compliant with ISO 14801 and one with a modified load adaptor (non-ISO). The different IAC designs varied in the taper, diameter, and cone height. The cone angle mismatch (Cam) between the implant and abutment was considered. A torque of 20 Ncm and oblique loads (up to 400 N) were simulated. Results: The stresses produced by the screw-tightening torque varied among the different IAC designs. The contact height was approximately 0.3 mm for Designs A and B, and less than 0.03 mm for Design C. Under oblique loads, Design A maintained IAC sealing without gap formation up to 400 N. With the ISO adaptor, gaps appeared in Design B at 300 N and in Design C at 90 N. The non-ISO adaptor resulted in gap formation at 160 N for Design B and at 50 N for Design C. Conclusions: The IAC design and cone angle mismatch significantly influenced microgap formation, with some designs showing zero gaps even when the oblique load reached 400 N. The non-ISO adaptor increased gap formation in IACs B and C.