Effects of lmplant Diameter and Prosthesis Retention System on the Reliability of Single Crowns

Purpose: The probability of survtval of implant-supported prostheses may be affected by the interplay between ditferent implant diameters supporting screwed or cemented crowns. The purpose of this study was to investigate the effect of tmplant diameter and prosthesis retention system on the reliability and failure modes of single crowns.

Material and Methods: lntemal-hexagon tmplants were divided into six groups (n = 21 each) according to implant diameter (3.3, 4.0, or 5.0 mm) and crown retention system (screwed or cemented). Abutments were torqued to the implants, and crowns were then fixed and subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for missions of 50,000 cycles at 100, 150, and 200 N were calcutated. Failure anatysis was performed.

Results: Cemented systems presented higher reliability than screwed ones, except between 3.3-mm-diameter cemented and screwed systems at a load of 100 or 150 N. Failure modes were restricted to the abutment screw and varied with tmplant diameter only in the cement-retained groups.

Conclusion: Higher reliability was observed for cement-retained crowns and implants of larger diameter compared to screw-retained and smaller dia meter. Failure modes differed between groups.

Estevam A. Bonfante, Erika O. Almeida, Fabio C. Lorenzoni and Paulo G. Coelho

INT J ORAL MAXiLLOFAC IMPLANTS 2015;30:95-101. doi: 10.11607/jomi.3545