CAD/CAM高嵌体与全冠修复上颌前磨牙的抗折性能研究

Study on Fracture Resistance of Maxillary Premolars Restored with CAD/CAM Onlays and Crowns

目的:比较不同缺损类型的上颌前磨牙分别行高嵌体与全冠修复后的抗折强度。方法:收集大小形态相似的64颗离体上颌第一前磨牙,随机分为4组(n=16),分别制备成以下缺损类型:A牙合面缺损1/3组,B牙合面缺损1/2组,C邻牙合面缺损1/3组,D邻牙合面缺损1/2组。各组按照修复方式不同再分成两个亚组(n=8),A1-D1组行IPS e.max CAD高嵌体修复,A2-D2组行IPS e.max CAD全冠修复。在万能力学测试机上测试各组抗折力,记录折断力值、折断模式并进行统计学分析。结果:高嵌体与全冠抗折力最大值均出现在A组,分别为(1203±148)N和(985±103)N。高嵌体修复组中A1组和B1组抗折强度明显高于C1组和D1组(P<0.05),全冠修复组中A2组和B2组抗折强度明显高于C2组和D2组(P<0.05)、C2组明显高于D2组(P<0.05)。同种缺损类型两种修复方式比较高嵌体抗折强度明显高于全冠(P<0.05)。各组间折裂模式无明显差异(P>0.05)。结论:前磨牙缺损洞型会对修复强度产生影响,牙合面缺损及邻牙合缺损前磨牙行高嵌体修复较全冠抗折强度更高,可优先选择使用。

Objective:To compare the fracture resistance of defected maxillary premolars restored with onlay and crown,respectively.Methods:Sixty-four maxillary first premolars with similar size and morphology were randomly divided into four groups(n=16).The following defect types were prepared respectively:group A had 1/3 defect of occlusal surface;group B had 1/2 defect of occlusal surface;group C had 1/3 defect of proximal-occlusal surface;and group D had 1/2 defect of proximal-occlusal surface.Each group was divided into two subgroups according to different restore methods(n=8),A1-D1 were restored by IPS e.max CAD onlays,and A2-D2 were restored by IPS e.max CAD crowns.The maximum loading value and failure mode were analyzed.Results:The maximum fracture resistance of onlays and crowns,i.e.(1203±148)N and(985±103)N,appeared in group A.Among onlay restoration groups,fracture resistances of group A1 and B1 were significantly higher than those of group C1 and D1(P<0.05).Among crown restoration groups,fracture resistances of group A2 and B2 were significantly higher than those of group C2 and D2(P<0.05),and C2 was significantly higher than D2 group(P<0.05).Within the same defect type,fracture resistances of onlays were significantly higher than those of crowns(P<0.05).There was no significant difference in the fracture mode among all groups(P>0.05).Conclusion:Defect types of premolar affect fracture resistance.For occlusal and proximal-occlusal defected premolars,fracture resistance of onlays was higher than that of crowns.