Marginal Accuracy and Fracture Resistance of Cement Retained, Screw Retained and Combined Cement Screw Retained Implant Supported Zirconia and PEEK Crowns

Authors

1 Assistant lecturer of Crowns and Bridges Department, Faculty of Dental Medicine for girls, Al – Azhar University.

2 Professor of Crowns and Bridges, Faculty of Dental Medicine for girls, Al–Azhar University

3 Lecturer of Crowns and Bridges, Faculty of Dental Medicine for girls, Al–Azhar University

Abstract

ABSTRACT: Purpose: This study was aimed to evaluate the marginal accuracy and fracture resistance of the implant supported by cement, screwed type or combination of both cemented and screwed Zirconia and PEEK crowns. Materials and Methods: Thirty six implant supported molar crown were chosen in this study then divided into three groups (n=12) Group I: cement-retained, Group II: screw-retained and Group III: combined cement-screw retained, then each group was further subdivided into two subgroups (n=6) according to superstructure material. Subgroup A: Zirconia crowns and Subgroup B: PEEK. After cementation or screwing of the crowns, they were subjected to thermo cycling. Then the marginal gap, fracture resistance and failure mode were evaluated for all the tested crowns. Results: The results of the current study recorded that the marginal gap for PEEK crowns was higher than that for the Zirconia one moreover; it was increased after cementation for both materials. Regarding the fracture resistance the highest values were recorded in group III for both materials followed by group I Zirconia and the least value was recorded in group I PEEK. Regarding the failure modes they were either cracks, chipping of veneer, crown fracture and fixture failure. Conclusions: For all tested crowns, the marginal gap distance was within the acceptable ranges. The fracture resistance of Zirconia crowns was greater than PEEK crowns.

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