不同桩核材料对下颌第一双尖牙抗折强度影响的实验研究

Effect of different post-core materials on fracture strength of first mandibular premolar

目的:比较三种临床常用纤维桩系统以及钴铬合金铸造金属桩核修复的下颌第一双尖的牙抗折性能,并分析产生影响的因素。方法:选择临床因牙周病或成人正畸拔除的单根下颌第一双尖牙共80颗,完善根管充填治疗后,随机分成A、B、C、D四组,保留2mm牙本质肩领预备牙体后分别用A组Parapost玻璃纤维桩+树脂核+金属烤瓷全冠修复,(法国RTD公司),B组TENAX玻璃纤维桩+树脂核+金属烤瓷全冠修复(瑞士康特公司),C组D.T.Light石英纤维桩+树脂核+金属烤瓷全冠修复(美国Bisco公司),D组铸造钴铬合金桩核+金属烤瓷全冠修复。所有样本于釉牙本质界下2mm处用自凝塑料包埋,然后用特制的夹具固定于万能材料测试机(instron2343,美国)上测试其折裂强度,加载点位于全冠颊尖顶上,加载方向与牙体长轴成135°夹角,加载速度为0.5mm/min,持续加载直至标本发生折裂,记录标本发生破坏时的瞬间力值及实验牙的折裂类型。结果:A、B、C、D四组离体牙桩核冠修复后牙体析断时的最大载荷分别为(376.8±47.4)N、(413.6±55.3)N、(602.8±75.8)N、(1012.4±105.3)N。A组与B组抗折强度及破坏性断裂相比(P>0.05),A、B两组分别与C、D两组经比较,其抗折强度差异有统计学意义(P<0.05)。破坏性折断D组明显高于ABC三组,P<0.05。结论:桩核材料修复下颌第一双尖牙的强度为铸造钴铬金属桩核>石英纤维桩>玻璃纤维桩核材料,但纤维桩核材料更有利于保护牙根。

Objective To compare the fracture strength of the endodontically treated mandibular first premolar which was restored by using different fiber posts and cast-alloy post.Method Total of 80 endodontically treated mandibular first premolars retaining 2.0 mm coromal dentine ferrule were divided into four groups randomly,then they were prepared and restored with three different types of fiber post and Co-Cr casting alloy.After the porcelain fused to metal crowns were fabricated respectively,we placed the testing assembly in a universal testing machine and loaded each specimen to fracture.For each specimen,we recorded the load to fracture （in Newtons） and the fracture type of the teeth specimen.The results were analyzed by ANOVA,with the use of SPSS 13.0 software package.Results Cast-alloy （D） group showed the highest fracture resistance of （1 012.4 ± 105.3） N,quartz post（C） group showed the second higher of （602.8 ± 75.8） N,and the two glass post（A and B） group showed the most fragility at （376.8 ± 47.4） N,（413.6 ± 55.3） N,strength difference of different types of material have statistical meaning（P〈0.05） .Conclusion The cast alloy posts show a significantly higher level of fracture strength compared to quartz posts,as the quartz posts show to the glass posts carbon posts （P〈0.05） .However,the fracture types of all the 3 fiber posts allow the possibility of restoration.The fracture types of cast alloy show more distructive.