桩长度对核桩冠修复体脱位力的影响

目的研究桩长度对核桩冠修复体脱位力的影响。方法用有机玻璃模拟不同桩长牙根,常规铸造桩核,均以磷酸锌粘固,以测试机进行拉伸测试,加载速度10mm/min,至桩核松动、脱位,记录最大载荷,同时测试有机玻璃与铸造金属的平面粘结力,测算桩核的粘结力大小及桩核的机械嵌合力大小。结果桩长7.0mm、7.5mm、8.0mm、8.5mm、9.0mm组脱位力分别为(203.25±57.19)N、(213.63±45.06)N、(234.44±59.27)N、(317.75±60.94)N和(334.25±58.00)N,桩长(L)与脱位力(D)、粘结力(B)及机械嵌合力(M)呈线性关系。其回归方程分别为D=73.225L-325.776,B=0.442L 9.951,M=72.676L-334.338。结论机械嵌合力在脱位力中起主要作用,而桩长对于机械嵌合力的大小的影响使桩长成为影响核桩冠脱位力的重要因素,临床上应使桩长达到根长的2/3~3/4较为理想。

Effects of Post Length on the Dislocation of Post and Core Crown

OBJECTIVE: To evaluate the effects of the length of post on the dislocation of cast post and core crown. METHODS: Forty simulated tooth roots made of polymethyl methacrylate were divided into five groups according to different length of post. These cast post and core were bonded with zinc phosphate cement. Then these specimens were strectched on the INSTRON-4302 by the speed of 10 mm/min. The maximum of load was recorded. RESULTS: The loads of 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm were (203.25 +/- 57.19) N, (213.63 +/- 45.06) N, (234.44 +/- 59.27) N, (317.75 +/- 60.94) N, (334.25 +/- 58.00) N respectively. Linear regression analysis revealed the linear relationship of post length with dislocation, bonding, and mechanical interlocking; the values of r being 0.676, 1.000, 0.949; the regression equations being D = 73.225L - 325.776, B = 0.442L + 9.951, M = 72. 676L-334. 338. CONCLUSION: Mechanical interlocking is the main factor in dislocation of post and core crown. The length of post should be increased from 2/3 to 3/4 of the length of tooth root when prepared in clinic.