目的:比较3种高嵌体材料修复前磨牙MOD洞型的抗折性能.方法:选取50个健康离体上颌前磨牙,随机分为1个对照组和Ⅰ、Ⅱ、Ⅲ、Ⅳ4个实验组(n＝10).对照组不作任何处理;4个实验组常规根管预备和充填后进行高嵌体MOD洞型预备,其中Ⅰ、Ⅱ、Ⅲ组颊舌尖预备2 mm,Ⅳ组预备1 mm.然后Ⅰ组采用间接复合树脂模块修复,Ⅱ组采用二硅酸锂加强型玻璃陶瓷修复,Ⅲ、Ⅳ组采用氧化锆高嵌体修复.最后用万能材料试验机在负荷1 800 N时检测各组样本的抗折性能,体视显微镜下观察样本折裂的类型.结果:对照组及Ⅰ、Ⅱ、Ⅲ、Ⅳ组抗折力(N)分别为1 135.92 ± 228.61、687.58 ± 107.66、705.41 ± 203.78、1 572.84 ± 243.53和1 012.65 ± 193.80,Ⅲ组与其他各组比,P＜0.05;Ⅳ组与对照组相比、Ⅰ组与Ⅱ组相比,P＞0.05.Ⅰ、Ⅱ组样本折裂主要为E型,其次为B型;Ⅲ、Ⅳ组样本折裂主要为B型和D型.结论:对于根管治疗后的前磨牙,用氧化锆高嵌体修复较间接复合树脂、二硅酸锂加强型玻璃陶瓷高嵌体修复具有更高的抗折性.%AIM:To compare the fracture resistance and modes of failures of three different aesthetic MOD onlays on endodontically treated premolars. METHODS:50 sound maxillary premolars were selected,10 untreated teeth were used as the controls.The other 40 premolars were subjected to standardized MOD onlay preparation and root canal treatment and divided into 4 groups(n＝10). Onlays of indirect composite and lithium disilicate ceramic were re-spectively prepared for the restoration of the MOD cavity of groupⅠandⅡ,onlays of Full Zirconiafor for groupⅢandⅣ. In groupⅠ,ⅡandⅢbuccal and palatal cusps were reduced by 2 mm,and in groupⅣby 1 mm. All onlays were cemented using Multilink Automix. All the samples of the 5 groups were subjected to fracture resistance test on univer-sal testing machine. The fractured surfaces were observed under stereo-microscope. RESULTS:The fracture resist-ance(N)of group control,Ⅰ,Ⅱ,Ⅲ and Ⅳ was 1 135.92 ± 228.61,687.58 ± 107.66,705.41 ± 203.78, 1 572.84 ± 243.53 and 1 012.65 ± 193.80 respectively (groupⅢvs the other groups,P＜0.05;groupⅠ,ⅡorⅣvs the control,P＞0.05). No crack was observed in the restorations of group Ⅲ. The restorations of group Ⅰ and Ⅱshowed mainly type E fracture mode followed by type B;those of groupⅢandⅣshowed mainly type A fracture mode. CONCLUSION:Full zirconia MOD onlay has higher fracture resistance for endodontically treated premolars than the other MOD systems.
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