牙本质肩领形态对上颌中切牙抗折性的影响

The effect of different ferrule designs on fracture resistance of maxillary incisors

目的:研究根管治疗后进行铸造金属桩核和烤瓷冠修复的上颌中切牙,不同牙本质肩领形态对牙齿抗折强度和破坏模式的影响。方法:加工30颗标准上颌中切牙密胺模型牙,按照牙本质肩领形态设立完整牙本质肩领、腭侧、唇侧及近中肩领和无肩领5组,分别进行金属桩核冠修复。修复后进行静态力学加载实验,对最大负载力进行单因素方差分析。结果:完整、腭侧、唇侧、近中及无肩领组的最大负载力均值分别是805N、598N、431N、538N、439N。完整肩领组的破坏模式均为环形折裂,腭侧肩领组主要为斜行折裂,其他3组均为纵行折裂。结论:对于根管治疗后的上颌中切牙,牙本质肩领形态影响牙齿的抗折性。

Objective:The purpose of this in vitro study was to investigate the effect of ferrule for mon the fracture resistance and failure mode of maxillary incisors endodontically treated and restored with casting post core.Methods:Thirty standard maxillary central incisor model teeth were divided into 5 groups(n=6)according to the ferruleform which were complete ferrule,labial ferrule,palatal ferrule,mesial ferrule and no ferrule.The teeth received casting post core and complete metal crown restorations.All specimens were simultaneously exposed to statically loaded until failure in a universal testing machine(crosshead speed=1 mm/min).The data were analyzed with one-way ANOVA and post hoc comparisons(α=0.05).Results:The median failure load(P<0.001)was 805 N、598 N、431 N、538 N and 439 N for the complete ferrule,palatal ferrule,labial ferrule,mesial ferrule and no ferrule groups,respectively.The failure mode of the complete ferrule group was ring fracture,the predominant failure mode of the palatal ferrule group was an oblique palatal to facial root fracture,and the other three groups were longitudinal fracture.Conclusion:The ferrule location affects the fracture resistance of endodontically treated maxillary incisors.