%0 Journal Article %T The Effect of Finish Line Design on the Fracture Strength of Zirconia Copings %J Journal of Dentistry %I Shiraz University of Medical Sciences %Z 2345-6485 %A Hashemi Ardakani, Zahra %A Khorsandipour, Sahar %A Mohghegh, Mina %A Ghoreishian, Seyed Ahmad %A Khaledi, Amir Ali Reza %D 2019 %\ 12/01/2019 %V 20 %N 4 %P 271-275 %! The Effect of Finish Line Design on the Fracture Strength of Zirconia Copings %K Zirconia ● Preparation ● Fracture Strength ● CAD/CAM %R 10.30476/dentjods.2019.77720. %X Statement of the Problem: One of the major concerns about all ceramic crowns is their fracture resistance. Purpose: The purpose of this in vitro study was to evaluate the effect of two marginal designs (shoulder 90°, shoulder 135°) on the fracture resistance of zirconia copings. Materials and Method: In this in vitro study, 20 brass dies were prepared using milling machine: 10 with 1mm width shoulder 90° marginal design and the other 10 with 1mm width shoulder 135° finish line design. Zirconia cores with 0.5mm thickness and 30μm cement space were fabricated on brass dies. The copings were cemented on the dies and fracture test was done using a universal testing machine. Data were analyzed using Mann-Whitney test. Results: The mean value of fracture resistance for shoulder 90° finish line design were 368.3±109.4 N and for shoulder 135° finish line design were 518.4±115.5 N. Data analysis revealed a statistically significant difference between groups (p < 0.05). Conclusion: The results of this study showed that the finish line design of zirconia copings influences their fracture resistance. A 135° shoulder finish line design can improve the fracture resistance of zirconia crowns. %U https://dentjods.sums.ac.ir/article_45001_b30a510cf43cef288b88164cb115f068.pdf