Effect of occlusal thickness design on the fracture resistance of endocrowns restored with lithium disilicate ceramic and zirconia

doi:10.7518/hxkq.2020.06.007

Abstract

Abstract:

Objective This study aimed to investigate the effect of occlusal thickness design on fracture resistance of endocrowns restored with lithium disilicate ceramic and zirconia. Methods A total of 24 artificial first mandibular molars were randomly divided into four groups with six teeth in each group as follows: group lithium disilicate ceramic-2 mm (lithium disilicate ceramic, with an occlusal thickness of 2 mm and a retainer length of 4 mm); group lithium disilicate ceramic-4 mm (lithium disilicate ceramic, with an occlusal thickness of 4 mm and a retainer length of 2 mm); group zirconia-2 mm (zirconia, with an occlusal thickness of 2 mm and a retainer length of 4 mm); and group zirconia-4 mm (zirconia, with an occlusal thickness of 4 mm and a retainer length of 2 mm). After adhesive cementation (RelyX Ultimate Clicker), all specimens were subjected to thermocycling (10 000 cycles). The specimens were subjected to fracture resistance testing at a 135° angle to the teeth at a crosshead speed of 0.5 mm·min^-1 in a universal testing machine. Data were analyzed with ANOVA and Tukey’s HSD test by SPSS 15.0. The failure modes were classified. Results The fracture resistances of groups lithium disilicate ceramic-2 mm, lithium disilicate ceramic-4 mm, zirconia-2 mm, and zirconia-4 mm were (890.54±83.41), (2 320.87±728.57),(2 258.05±557.66), and (3 847.70±495.99) N respectively. Group zirconia-4 mm had the highest fracture resistance, whereas group lithium disilicate ceramic-2 mm had the lowest. Conclusion The fracture resistance of molar endocrown with zirconia is higher than that with lithium disilicate ceramic. Increasing the occlusal thickness can improve the fracture resistance but increase the risk of fracture of abutment.

Key words: endocrown, fracture resistance, thickness, retainer, lithium disilicate ceramic, zirconia

CLC Number:

R783.3

Lin Zhenxiang, Pan Zaixing, Ye Qiqing, Zheng Zhiqiang, Lin Jie. Effect of occlusal thickness design on the fracture resistance of endocrowns restored with lithium disilicate ceramic and zirconia[J]. West China Journal of Stomatology, 2020, 38(6): 647-651.

Figures/Tables 5

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组别	可再次修复	不可再次修复	可再次修复率/%
二硅酸锂2 mm	6	0	100
二硅酸锂4 mm	3	3	50
氧化锆2 mm	5	1	83
氧化锆4 mm	2	4	33