离体上颌前磨牙根管治疗两个阶段抗折力及折裂模式的比较

Fracture resistance and type of fracture in model of upper premolars at two different stages of root canal therapy in vitro

目的:对根管治疗术中根管预备结束和充填完成两个阶段牙齿的抗折力进行定量比较,并对折裂模式进行观察。方法:以上颌离体前磨牙30个为研究对象,先根据形态分成区组,每区组各3个牙。再用抽签法将其随机分入处理组,每组10个。对照组:不作任何处理;预备组:模拟开髓和根管预备;完成组:与预备组相同的处理后,进行根管充填和复合树脂修复。用万能测试仪测试牙齿的抗折力;将折裂模式分为"轻度"和"重度"两级,由2名专家独立盲法评价。结果:各组的抗折力分别为:(1171.2±140.10)N,(514.8±219.23)N和(911.0±86.77)N。对照组最高,预备组最低。方差分析显示组间差别显著(F=26.50,P=0.0003)。各组折裂牙属于"重度"者分别有2、6、4个,对照组最少,预备组最多。结论:根管治疗术会削弱牙齿的抗折力,尤其在根管预备结束阶段。

AIM：To determine the quantity of fracture resistance and fracture model as well at two stages of root canal therapy. METHODS： Every 3 upper premolars were put together based on their shapes as a block, then they were divided into 3 groups by drawing lots with each group of 10 teeth. Group 1, not any intervention were given as control. Group 2, access cavity and root canal preparation were made. Group 3, treatment procedure is similar as group 2, then, the canal was obturated and the cavitiy was restored with composite resin. Universal testing machine was used for testing each tooth fracture resistance. Total values were analyses by Two - way ANOVA （ α = 0.05 ）. The model of fracture of teeth was divided into ＂moderate＂ and ＂severe＂ and decided blindly by two dentists. RESULTS ： The compression force resistance in groups were （ 1171.2 ± 140.10） N, （ 514.8 ± 219.23 ） N and （ 911.0 ± 86.77 ） N respectively . Significant differences were found between groups（ F = 26.50, P = 0. 0003 ） with the lowest of group 2 . The teeth with ＂severe fracture＂ were 2, 6 and 4 respectively in the group 1, 2 and 3. CONCLUSION： Root canal therapy process can weaken the fracture resistance of tooth, especially at the stage of root canal was prepared.