Studies on Marginal Fracture and Marginal Leakage Around Direct Composite Resin Inlay Restorations.

本研究的目的是研究三种边缘形式--对接、直斜面和圆斜面的复合嵌体在模拟咬合力作用下的边缘断裂情况，并评价其临床性能。间接复合嵌体用双固化树脂粘固剂插入洞内。一半的修复牙齿在4到60摄氏度之间进行了5000次热循环，另一半储存在水中。在所有牙齿经受设计用于不锈钢棒（重量：lkg）以125次/min从1.5cm的高度反复下落的载荷循环测试之后，将它们浸入品红溶液中24小时。观察边缘断裂和渗漏程度。并以直接复合充填法修复的牙作为对照。临床上，采用不同边缘形态的复合嵌体修复磨牙龋坏。使用USPHS标准在0、3和6个月后进行临床评估。用扫描电镜观察了牙槽嵴边缘的完整性。间接复合嵌体边缘断裂发生率低于直接复合嵌体。而热循环则使其增加，而直接复合修复则无热循环效应.在非热循环间接复合嵌体中，断裂频率的顺序为直斜面>圆斜面>对接.热循环后两种接头边缘泄漏程度的大小顺序为对接接头>圆坡口接头>直坡口接头.热循环处理后间接复合嵌体周围的边缘渗漏明显增加.临床观察6个月时，复合材料嵌体周围无边缘断裂。

The purpose of the present study was to investigate the marginal fracture of composite inlay with each of three marginal forms-butt joint, straight bevel and round bevel, under simulated occlusal force and to estimate their clinical performance.Six class 1 cavities with each marginal form were prepared on the surfaces of extracted incisors. Indirect composite inlay was inserted into the cavity with a dual-cured resin cement. Half of the restored teeth was subjected to 5000 thermocyclings between 4 and 60ﾟC and the other half was stored in water. After all teeth were subjected to the load cycling test designed for a stainless rod (weight : lkg) to fall repeatedly from the height of 1.5cm at 125 times/min, they were immersed in fuchsin solution for 24 hours. Degree of marginal fracture and leakage were observed. The teeth restored by direct composite filling technique were also tested as control. In clinic, carious molar teeth were restored with composite inlay with each marginal form. Clinical-estimation was performed at 0, 3 and 6 months later, using a USPHS criteria. The marginal integrity of the restorations was also observed by SEM.Results were as follows ;1. The frequency of marginal fracture of indirect composite inlay was lower than that of direct composite restorations. However it was increased by thermocycling, while in direct composite restoration there was no effect of thermocycling.2. In indirect composite inlay without thermocycling, the order of the frequency of fracture was straight bevel>round bevel>butt joint.3. The order of the degree of marginal leakage around both restorations after thermocycling was butt joint>round bevel>straight bevel.4. Marginal leakage around indirect composite inlay was remarkably increased by thermocycling.5. In clinical estimation, no marginal fracture around composite inlay was observed at the period of 6 months.