The Effect of Finish Line Design on the Fracture Strength of Zirconia Copings

Hashemi Ardakani, Zahra; Khorsandipour, Sahar; Mohghegh, Mina; Ghoreishian, Seyed Ahmad; Khaledi, Amir Ali Reza

doi:10.30476/dentjods.2019.77720.

The Effect of Finish Line Design on the Fracture Strength of Zirconia Copings

Document Type : Original Article

Authors

Zahra Hashemi Ardakani ¹

Sahar Khorsandipour ²

Mina Mohghegh ¹

Seyed Ahmad Ghoreishian ¹

Amir Ali Reza Khaledi ¹

¹ Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.

² Undergraduate Student of Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.

https://doi.org/10.30476/dentjods.2019.77720.

Abstract

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.

Keywords

Zirconia ● Preparation ● Fracture Strength ● CAD/CAM

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