金属加强结构对后牙4单位金属烤瓷固定桥强度的影响

Influence of reinforcement designs in metal frameworks on the strength of veneering porcelain of 4-unit metal-ceramic fixed bridges

目的比较不同桥体加强结构设计对烤瓷固定桥瓷层强度的影响,为临床使用合适的金属桥架设计提供参考。方法对C5、C6缺失采用C4-C7金属烤瓷双端固定桥模型,在烤瓷固定桥金属基底的舌侧设计点状和带状加强结构,以无加强结构设计作为对照,在桥体中央垂直于咬合面进行加载(速度0.5mm·min-1),记录饰面瓷破坏时的载荷以及破坏的形式。采用SPSS11.0软件进行统计分析,比较瓷层失败时的最大载荷值组间差异(α=0.05),并探讨不同设计组间瓷层破坏形式的差异。结果3种不同设计组发生瓷裂时的平均最大载荷分别为(0.87±0.06)kN(无加强结构)、(1.03±0.15)kN(点状加强结构)和(0.93±0.10)kN(带状加强结构)。无加强结构组与点状加强带组的最大载荷差异具有统计学意义(P<0.05),其他组间差异无统计学意义(P>0.05)。在瓷层破坏形式上,各组间没有明显的差异,瓷层破坏的位置几乎都是在加载点周围和近远中固位体的连接体部位。结论金属桥架舌侧连接体区的点状加强结构对烤瓷桥强度可以起到明显的增强效果。

Objective To compare the effect of 3 different reinforcement designs in the metal frameworks on the strength of veneering porcelain of 4-unit metal-ceramic fixed bridges by means of load-to-failure method.Methods 4-unit metal-ceramic fixed bridges with contiguous missing of C5 and C6,with C4 and C7 as abutments were fabricated,with 3 different reinforcement designs of the metal frameworks：Non-reinforcement,lingual punctuate metal reinforcement,and lingual linear metal reinforcement.After cementation of the bridge,vertical loads were then applied on the occlusal surface at the center of the pontics on a testing machine（at a crosshead speed of 0.5 mm·min-1） until the first sign of porcelain crack appeared.Load-to-failure forces and modes of porcelain failure were recorded.The load-to-failure forces among the three different reinforcement design groups were statistically analyzed with SPSS 11.0 software,using one-way ANOVA and SNK comparison（α=0.05）,and the modes of porcelain failure were also compared.Results The load-to-failure forces of the bridges in the three reinforcement design groups were（0.87 ±0.06）kN（non-reinforcement）,（1.03 ±0.15）kN（lingual punctate metal reinforce ment）,and（0.93±0.10）kN（lingual linear metal reinforcement） respectively.Significant difference was found between non-reinforcement and lingual punctate metal reinforcement group（P 〈0.05）,while no significant difference was found between the other groups（P〉 0.05）.The modes of porcelain fracture were about the same in the three groups.Conclusion The bridges with punctuate reinforcement demonstrated the maximal load-to-failure forces.