Studies on Evaluating Method for Adhesive Durability of Posterior Composite Resin.

本文建立了一种新的评价后牙复合树脂与牙体粘结强度的方法。在该方法中，使用具有填充有树脂的圆柱形空腔的试样。树脂聚合固化后，由平底圆柱冲头推出。由此得到的粘结强度比常规剪切试验所得的粘结强度更接近于实际情况。实验结果表明，树脂与牙本质的粘结强度为1.31MPa，与牙釉质的粘结强度为5.82MPa。这些值分别为剪切试验所得值的46%和26%。我们还进行了估计，发现很大的拉应力发生在树脂/牙齿界面。这些拉伸应力不会发生在剪切测试中使用的标本，并被认为是负责减少粘结强度与建议的推出method.The后复合树脂反复压缩载荷下的粘接耐久性进行了研究。制备了盒形、带斜面盒形、碟形、带斜面碟形四种型腔，并进行了复合树脂充填。研究了两种充填方法，一种是一次完成的常规方法，另一种是分两步完成的方法。试件经受反复压缩载荷，并通过染料渗透试验评价粘合剂耐久性。结果表明，反复加载会促进边缘泄漏。碟形腔体的边缘渗漏量小于盒形腔体，斜面对提高两种腔体的耐久性都有很好的效果。填充方式对试件的耐久性影响不大，两步法填充试件的耐久性比两步法填充试件差，而常规一步法填充试件的耐久性比两步法填充试件差。

We developed a new method for the evaluation of bond strength of posterior composite resin to tooth. In this method, specimens having cylindrical cavities filled with resin are used. After polymerization and curing, resin are pushed out by flat-based cylindrical punch. Bond strength thus obtaired are considered to have more close reiationships to the actual ciinic condition than those obtained by conentional shear test. We conducted several experiments and found that bond strength of resin to dentin was 1.31Mpa, and that to enamel was 5.82MPa. These values were 46% and 26%, respectively, of those obtained by shear test. We also carried out estimations and found that very large tensile stresses occur at resin/tooth interface. These tensile stresses do not occur in specimens utilized in shear test, and are considered to responsible for the reduction of bond strength noted with the proposed push-out method.The adhesive durability of posterior composite resins under repeated compressive loads was investigated. Four types of cavities, i.e. box, box with bevel, saucer, saucer with bevel were prepared and filled with composite resins. Two filling procedures were examined, one was conventional method in which filling was done at one time, while in other method, filling was completed in two steps. Specimens were subjected to repeated compressive loads, and adhesive durability was evaluated by dye penetration test. It was found that the marginal leakages were promoted by repeated loadings. The saucer cavity showed less marginal leakage than box cavity, and bevel excellent effects on the improvement of durability of both types of cavities. Filling procedure has little effect on durability, and specimens filled by two-step method show poorer durability than specimens filled by two-step method show poorer durability than specimens filled by conventional one-step method.