J Korean Dent Sci.  2024 Dec;17(4):210-220. 10.5856/JKDS.2024.17.4.210.

Effects of Horizontal Width and Thickness of Zirconia Crown Margin on Fracture Strength

• Jeon SJ
• Son K
• Kim MJ
• Chang KW

• KMID: 2564311
• DOI: http://doi.org/10.5856/JKDS.2024.17.4.210

Abstract

Purpose
The purpose of this study was to evaluate the fracture strength of zirconia crowns of varying margin thicknesses.
Materials and Methods
A model of the maxillary right first molar (Nissin, Kyoto, Japan) was prepared to create an abutment, which was fabricated into a metal die via a 3D metal printer. CAD software (exocad GmbH, Darmstadt, Germany) was used to design the crowns. A total of eight groups were generated: initially separated by margin thickness (0.1 mm and 0.8 mm), and then further divided by horizontal margin widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. Zirconia crowns were designed for each group’s working models (N=10). Crown fracture strength was assessed using a universal testing machine (Shimadzu, Kyoto, Japan), applying a compressive load until fracture and recording the maximum load. A scanning electron microscope was employed to observe fracture patterns. Fracture strength results were analyzed using one-way ANOVA, with the Tukey HSD test applied for post-hoc analysis (α=0.05). Results: Zirconia crown fracture strength significantly improved with increased horizontal margin width (P<0.001). However, margin thickness had no statistically significant effect on fracture strength (P=0.513).
Conclusion
Optimizing the horizontal margin width of zirconia crowns enhances their durability and performance.

Keyword

Zirconia crown; Fracture strength; Margin thickness; Crown fracture