聚合度对核桩冠桩核联合体固位力的影响研究

标准尺寸的有机玻璃模拟上中切牙牙根试件54个,分为桩道聚合度为0°、3.93°、5.71°、7.48°、11.31°、14.71°六组,制备铸造桩核后磷酸锌粘固剂粘固,进行拉伸试验测得固位力。用铸造圆片测试不同聚合度时的平面粘接力,换算出不同聚合度时的单位面积粘接力,计算出桩固位力中粘接力的大小以及摩阻力大小和所占比例。并对固位力、摩阻力、单位面积粘接力、单位面积固位力、单位面积摩阻力对聚合度之间进行回归分析。结果显示桩固位力和摩阻力、磷酸锌粘接力随聚合度增大而减小,统计分析组间有差异,P<0.05,本试验显示为了获得较大的固位力,临床医生应该尽可能减少桩的聚合度。

Influence of Different Convergence Angles on the Retention of Cast Metal Post and Core

Fifty-four simulated tooth roots made of polymethacrylate (PMMA) were divided into six groups according to the root canal convergence angles of 0 degrees, 3.93 degrees, 5.71 degrees, 7.48 degrees, 11.31 degrees, 14.71 degrees. Cast post and cores were manufactured and cemented with Zinc phosphate cement (ZP). The retention capacities of the posts were tested. The bonding strength of ZP at different convergence angles were tested with some casted wafers, and linear regression was made. So the effect of interlocking and the proportion could be calculated. With these results, we made some curvilinear regressions. The results showed that the retention of cast post declined and the bonding strength of ZP fell with the increase of convergence angles. There were significant differences in the bonding strength and retention among groups, P<0.05. The experiment indicates that the dentists should reduce the convergence angles of posts as much as possible to obtain greater retention.