前磨牙楔状缺损修复后的抗折裂强度研究

Study on the fracture-resistant forces of premolars with wedge-shaped defects post restoration

目的研究楔状缺损深及牙齿颊舌径的1/4或1/2的前磨牙采用不同材料充填后牙体的抗折裂强度及牙齿折裂模式。方法收集正畸拔除的新鲜前磨牙60颗,颊侧颈部设计颊舌径1/2和1/4楔状缺损,对1/2深度根管治疗后分别选择复合树脂、复合体或玻璃离子水门汀三种材料充填,运用万能材料试验机对前磨牙颊尖垂直向载力直至牙体断裂。记录牙断裂时的受力数值,并观察断裂模式。结果不同深度的楔状缺损其抗折裂强度不同,但各组间差异无统计学意义(P>0.05)。充填后前磨牙抗折裂强度显著增加(P<0.01),而不同充填材料对牙齿抗折裂强度无显著差异(P>0.05)。结论楔状缺损深及前磨牙颊舌径的1/4以上时容易导致前磨牙折裂。材料充填后可以提高前磨牙的抗折裂能力且与充填材料的种类无关。

Objective The aim of this study was to examine the fracture-resistant forces and the modes of fracture when premolars had wedge-shaped defects with different depths and the wedge-shaped defects were restored with different restorative materials. Methods Sixty human Premolars extracted for orthodontic reasons were used. After wedge-shaped defects at the buccal cervix had been prepared into 1/2 or 1/4 bucco-lingual distance of the premolars, ten premolars per group were restored with one of three restorative materials （ composite resin, compomer and glass ionomer cement ） or without any filling material~. Vertical compress forces on the buccal cusps of the premolars were recorded until fracture. Results No statistical significant differences of fracture-resistant forces were found between the depths （ 1/2 ; 1/4 ） of wedge-shaped defects of the premolars, and among the different restorative materials. The fracture-resistant forces of premolars with wedge-shaped defects were significantly increased after the wedge-shaped defects were restored （P 〈 0.01 ）. Conclusions Wedge-shaped defects that are deeper than 1/4 bucco-lingual distance of premolars easily cause premolar fractures. After restored, fracture-resistant forces of premolars are increased but not related with filling materials.