三种桩核系统修复后离体牙抗疲劳性实验

目的 比较3种不同桩核系统修复的离体牙抗疲劳性差异.方法 30颗离体上颌中切牙,去除牙冠后用镍铬合金金属铸造桩核＋金属烤瓷冠修复（以下简称金属桩组）,进行疲劳实验和抗折实验;同时与平滑型和螺纹型石英纤维桩＋树脂核＋金属烤瓷冠修复的离体牙（以下简称平滑桩组和螺纹桩组）进行比较,记录显微镜下的牙根破损情况和牙冠折断时最大力值.结果 金属桩组、平滑桩组和螺纹桩组牙根的破损率分别为100％、60％和90％.金属桩组牙根破损率较其它2组差异具有统计学意义（P＜0.05）.金属桩组、平滑桩组和螺纹桩组牙根的折断力分别为136.22±41.26 N、133.77±33.12 N和169.44±47.14 N,3组间无显著性差异（P＞0.05）.结论 纤维桩较金属桩能够降低牙根破损率,但3种桩修复离体牙抗折力之间没有明显差异.

Fracture resistance of weakened roots restored with three kinds of post core systems

Objective To compare the difference in fracture resistance of weakened roots restored with three kinds of post core systems. Methods Thirty isolated maxillary central incisors whose crowns were removed were divided into three groups of ten and restored with post-core made of chrome-nickel casting metal and porcelain-fused-to-metal （ metal post group）, smooth type quartz fiber post and serrated type quartz fiber post combined with resin core and metal PFM （smooth type group and serrated type group ）, respectively. The fatigue and bending tests on these restored roots were performed and compared. The root damage observed by microscope and the maximum force at the root fracture were recorded. Results The root damage rates in metal post group（ 100% ）were significantly higher than in smooth type group （60%） and serrated type group （ 90% ） （ P 〈 0.05 ）. The breaking force of the three groups was 13.90kg, 13.65kg and 17.29kg in metal post group, smooth type group and serrated type group. The difference was not significant among the three groups. Conclusion The fiber post could reduce the root damage rate, but the fracture resistance of the three kinds of post core systems was not different.