复合树脂间接法和直接法修复的疲劳破坏研究

目的通过体外咀嚼模拟实验,比较复合树脂间接法嵌体和直接法充填修复的抗疲劳破坏能力。方法30颗牙冠完整离体磨牙制备Ⅱ类洞,随机分为3组,每组10颗牙。2个组以嵌体修复(分别用PermaCem-Dual和ParaCore-Dual粘接),第3组以复合树脂直接充填。24h后于冷热循环机械载荷(TCML)咀嚼模拟疲劳实验机上进行疲劳实验,经1000次5℃/55℃冷热循环,1.2×106次50N机械负荷疲劳实验后,体视显微镜观察粘接破坏裂纹染色剂渗透情况,图像分析管理系统测定每个样本颈缘染色剂渗透距离。结果2个嵌体修复组间的破坏和裂纹染色差异无统计学意义(P>0.05),2个嵌体组均优于直接充填组(P<0.05)。结论复合树脂间接法嵌体修复较树脂直接充填具有更好的抗疲劳破坏能力,而2种不同粘接剂之间差异不明显。

The Fatigue Failure Study of Direct and Indirect Resin Composite Restorations

Objective To study the fatigue failure characteristics of direct and indirect resin composite restorations in-vitro by using a simulator to mimic chewing.Methods Thirty extracted human molars (prepared with standardized class Ⅱcavities, not bevelled) were randomly divided into three groups (n=10): two indirect resin composite restorations groups (cemented with PermaCem-Dual and ParaCore-Dual respectively) and a direct resin composite restorations group. All the specimens were fixed on a thermocycling and mechanical loading (TCML) chewing simulator. After thermocycling and dynamic mechanical loading ( 1 000, 5 ℃/55 ℃, 1.2×10⁶, 50 N, 1.7 Hz), the specimens were immersed in a 1% Gentian violet solution for 24 h, rinsed, and then incised in a mesial-distal direction. Section surfaces were observed with an optical microscope.Results Compared with the direct composite group, both indirect composite groups showed a significant reduction in the incidence of micro-leakage of gingival margin (P<0.05), but there was no significant difference between the two indirect groups (P>0.05).Conclusion Within the limitations of this in-vitro study, indirect resin composite restoration can tolerate more fatigue failure than the direct-placement light-cured-only composite. The resin composite inlay technique is a promising method introduced to reduce the problem of shrinkage.