EFFECT OF FINISH LINE DESIGN AND THERMO-MECHANICAL AGING ON THE FRACTURE RESISTANCE OF TWO TYPES OF MONOLITHIC ZIRCONIA CROWNS

Document Type : Original Article

Authors

1 Assistant Professor, Crowns and Bridges Department, Faculty of Dental Medicine, Al Azhar University, Egypt

2 Assistant Professor, Dental Biomaterials Department, Faculty of Dental medicine, Al-Azhar University, Egypt

3 Lecturer, Crowns and Bridges Department, Faculty of Dental Medicine, Al Azhar University, Egypt

Abstract

Objectives: The purpose of this study was to compare the fracture resistance of two types of CAD/CAM monolithic zirconia crowns with two finish line designs after thermo-mechanical aging.
Materials and methods: A total of 40 zirconia crowns were milled and divided into two groups Bruxzir and Prettau zirconia (n=20). Each type of zirconia crowns was divided into two groups according to the finish line design, chisel (CH) and deep chamfer (DC) groups (n=10) After cementation of crowns to their corresponding dies, half of each group was subjected to thermo-mechanical aging, then fracture resistance was measured.
Results: Statistical analysis showed the highest fracture resistance mean±SD value was recorded with Bruxzir non-aged CH group (3432.22±462.4), while the lowest fracture resistance mean±SD values was recorded with Prettau aged DC group (2658.97±417.2) as indicated by three-way ANOVA test (F= 11.8806, p= 0.0087<0.05).
Conclusion: Within the limitations of this study, fully contoured zirconia crowns showed high resistance to failures and a minimally invasive preparation design should be determined as the optimal choice.

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