Lin Zhen-Xiang, Pan Zai-Xing, Ye Qi-Qing, Zheng Zhi-Qiang, Lin Jie
Dept. of Stomatology, Fujian Provincial Governmental Hospital, Fuzhou 350001, China.
Dept. of VIP Dental Service, School and Hospital of Stomatology, Fujian Medical University, Fuzhou 350002, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2020 Dec 1;38(6):647-651. doi: 10.7518/hxkq.2020.06.007.
This study aimed to investigate the effect of occlusal thickness design on fracture resistance of endocrowns restored with lithium disilicate ceramic and zirconia.
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.
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.
本研究旨在探讨咬合面厚度设计对用二硅酸锂陶瓷和氧化锆修复的嵌体冠抗折性能的影响。
将24颗人工下颌第一磨牙随机分为四组，每组6颗牙，分组如下：二硅酸锂陶瓷-2mm组（二硅酸锂陶瓷，咬合面厚度2mm，固位体长4mm）；二硅酸锂陶瓷-4mm组（二硅酸锂陶瓷，咬合面厚度4mm，固位体长2mm）；氧化锆-2mm组（氧化锆，咬合面厚度2mm，固位体长4mm）；氧化锆-4mm组（氧化锆，咬合面厚度4mm，固位体长2mm）。用粘结剂（RelyX Ultimate Clicker）粘结后，所有标本进行热循环（10000次循环）。在万能试验机中，以0.5mm·min⁻¹的十字头速度，与牙齿呈135°角对标本进行抗折试验。数据用SPSS 15.0进行方差分析和Tukey's HSD检验。对失败模式进行分类。
二硅酸锂陶瓷-2mm组、二硅酸锂陶瓷-4mm组、氧化锆-2mm组和氧化锆-4mm组的抗折强度分别为（890.54±83.41）、（2320.87±728.57）、（2258.05±557.66）和（3847.70±495.99）N。氧化锆-4mm组抗折强度最高，而二硅酸锂陶瓷-2mm组最低。
氧化锆修复的磨牙嵌体冠的抗折性能高于二硅酸锂陶瓷修复的。增加咬合面厚度可提高抗折性能，但会增加基牙折断的风险。
