两种桩核系统修复对不同程度缺损磨牙抗折性能影响研究

An in vitro study of fracture resistance of molars with different dental defect using two post and core crown systems

目的探讨两种桩核系统修复对不同程度磨牙缺损的抗折性能影响,为临床选择桩核系统提供参考依据。方法收集2009年2—6月在山西医科大学口腔医院口腔外科门诊因牙周病拔除的完整人上颌第一恒磨牙30颗,随机分为3组,每组10颗。分别制备成轻、中、重度牙体缺损模型。各组再分别使用玻璃纤维桩+树脂核(FPC)+金属全冠修复和铸造镍铬桩核(CPC)+金属全冠修复,各5例。在电子万能力学试验机上进行静态压力加载,直至牙体断裂,记录折裂时的载荷值及折裂模式并进行统计分析。结果各组样本折裂时的载荷值为轻度缺损组>中度缺损组>重度缺损组;3组应用CPC修复系统折裂时的载荷值均大于应用FPC修复系统者。3种缺损组间差异均具有统计学意义(P<0.05)。FPC或CPC修复轻度牙体缺损的折裂载荷差异无统计学意义(P>0.05);而对于中、重度牙体缺损,应用FPC与应用CPC修复的折裂载荷差异有统计学意义(P<0.05)。应用FPC修复系统的样本折裂后86.67%(13/15)可再修复,而应用CPC修复系统的样本折裂后仅有20%(3/15)可再修复,差异有统计学意义(P<0.05)。结论牙体缺损的加重可导致抗折性能下降;磨牙轻度牙体缺损时,推荐选择玻璃纤维桩核冠修复;中、重度牙体缺损时,推荐选择铸造金属桩核冠修复;玻璃纤维桩核冠更利于折裂后再修复。

Objective To evaluate the effect of 2 different restorative systerms with varying amounts of remaining dentin on the fracture resistance and failure mode of endodontically treated maxillary first molars in order to explore the clinical design consideration.Methods Thirty human maxillary first molars were divided into 3 groups（n = 10）with respect to the uniform residual coronal dentin,defined as light,moderate,severe group at Stomatology Hospital of Shanxi Medical University from Feb.to Jun.2009.Then they were subdivided into 2 groups restored internally using a cast post and core（CPC group）,or a glass fiber post and core（FPC group）（n = 5）.All specimens were then restored with cast crowns.Static loading tests were performed on each specimen until failure（crack without a complete fracture）.Failure was classified as either favorable（allowing repair）or catastrophic（not allowing repair）.All the data was analyzed.Results The differences of the fracture resistance values were statistically significant between groups with different residual dentin and also between groups with different post-core crown systerms（P 0.05）.An increased residual dentin generally provided greater fracture resistance.The fracture resistance of the CPC group was higher than that of the FPC group in moderate and severe group.But no statistically significant difference in the subgroups of light group.The failure mode was favorable for 86.67%FPC specimens while for 20% CPC specimens.Conclusion Severity of dentin coloboma generally leads to reduction of fracture resistance.The cast post and core has more catastrophic failure potential,but it is recommended for use when little or no residual dentin remains.Alternatively,when the dentin coloboma is mild,the glass fiber post system restoration may be more suitable,since it demonstrates only a slightly lower fracture resistance than the cast post and core,but with a more favorable failure potential.