固位型设计对粘结桥固位的影响

目的:分析不同固位型设计对粘结桥固位的影响.方法:将45个铸造金属基牙后牙粘结桥模型试件,按固位设计分为基本固位C型组(对照组)、轴沟组和针道组,每组15个.分别测量粘结桥试件用Panavia F粘固24h后未疲劳和经过24万次、120万次模拟咀嚼疲劳后的最大(牙合)向固位力.结果:未经疲劳时,对照组最大固位力值(566.82±71.59 N)＜轴沟组(656.07±137.29 N)＜针道组(791.40±141.22 N).疲劳24万次后,对照组最大固位力值(539.37±88.26 N)＜轴沟组(599.19±82.38 N)＜针道组(710.98±165.73 N).疲劳120万次后,轴沟组最大固位力值(307.93±46.09 N)＜对照组(365.79±61.78 N)＜针道组(505.04±125.53 N).3种固位型之间以及经过不同咀嚼疲劳次数的同一固位型粘接桥最大固位力之间差异均有统计学意义(P＜0.001).在控制疲劳次数因素后,针道组固位力均大于轴沟组和对照组(P＜0.05),轴沟组和对照组之间差别无统计学意义(P＞0.05).经过120万次模拟咀嚼疲劳后不同固位型设计粘结桥的固位力均显著降低(P＜0.001).结论:与轴沟相比,针道辅助固位型可更有效地提高粘结桥的固位力.

Influence of retention-form design on the retention of resin-bonded fixed partial dentures

OBJECTIVE: To evaluate the influence of retention-form design of resin bonded fixed partial dentures (RBFPDs). METHODS: Forty-five metal replicas of posterior metal RBFPDs were divided into 3 groups(n=15):C shape(control group), C shape + axial groove, C shape + pin hole. All the replicas were luted with Panavia F cement and subgroup of 5 specimens were subject to 70 N compressive load cycling for 0 cycles, 240,000 cycles , and 1,200,000 cycles respectively .Half of the cycles was on the central fossa of the pontics and half on the buccal inclined surface of the lingual cusp. Forces for dislodgment of the specimens were applied along the long axis of the abutment at a crosshead speed of 1.0 mm /min. The separation forces were recorded as maximum retention force at the time of dislodgement. RESULTS: Separation forces of the C shape group (566.82+/-71.59 N)0.05). After 1,200,000 cycles, the retention force of the RBFPDs decreased significantly (P<0.001). CONCLUSION: To compare with axial groove, the design of pinhole retention form was conduced to the improvement of the retention force and durability of RBFPDs.