Effect of implant‒abutment connections on abutment screw loosening: An in vitro study

Abstract

Background. The widespread use of dental implants as a predictable treatment choice has drawn attention to their complications as a major challenge despite their high clinical success rates. In this context, loosening of the abutment screw in posterior single crowns is the most common problem; the use of adequate preload and proper anti-rotational features at implant‒abutment interface appear to be two main solutions to such a problem. The present study evaluated the effect of implant‒abutment connections in four different implant systems before and after cyclic loading. Methods. Intra-Lock, Dentis, Xive, and Dio implant systems were used in this study. Each system underwent one million cycles of dynamic forces eight times with a magnitude of 110 N. For each specimen after tightening the screw with a torque of 32 Ncm, the detorque values were measured and recorded by a digital torquemeter after and before cyclic loading. Data were analyzed by Kolmogorov-Smirnov, Levene’s, one-way ANOVA, and post hoc Tukey tests. Results. Initial detorque values between the study groups showed significant differences (P<0.0001). Pairwise comparisons showed significantly lower primary detorque values in the Dentis system compared to the three other systems (P<0.0001). After cyclic loading, significant differences were observed between the study groups (P<0.0001). Pairwise comparisons of the groups showed significant differences between all the systems after loading. Conclusion. The type of implant‒abutment connection is an essential factor influencing the amount of abutment screw loosening.

Keywords

• dental implants
• dental implant‒abutment connection