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

本研究的目的是在模拟咬合力的作用下，研究对接、直角和圆角三种边缘形态复合嵌体的边缘断裂，并评价它们的临床性能。在拔除的切牙表面制备了6个1类牙槽，每个牙槽的边缘形态各有一种。采用双固化树脂水泥将间接复合嵌体插入腔内。一半修复后的牙齿在4 - 60ºC之间进行5000次热循环，另一半保存在水中。所有牙齿进行不锈钢棒（重量：1kg）以125次/min的速度从1.5cm的高度反复掉落后，在品红溶液中浸泡24小时。观察边缘断裂和渗漏程度。以直接复合充填法修复的牙为对照。临床采用复合嵌体修复龋病磨牙。使用USPHS标准，在0、3和6个月后进行临床评估。通过扫描电镜也观察到修复体的边缘完整性。结果如下：1。间接复合嵌体的边缘断裂频率低于直接复合嵌体。而热循环对复合修复的影响较小，热循环对复合修复的影响较小。在不进行热循环的间接复合嵌体中，断裂频率的顺序为直斜b>圆斜>对接接头。热循环后两个修复体周围边缘渗漏程度的大小顺序为对接b>圆坡>直坡。热循环显著增加了间接复合嵌体周围的边际泄漏。临床估计，6个月期间复合嵌体周围未见边缘骨折。

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.