超声法取根管内折断的镍钛和不锈钢根管锉的效果比较

目的比较根管内折断的镍钛和不锈钢根管锉在超声取出率和根管壁切削量上的差异。方法选取离体人下颌切牙64颗，随机分为镍钛锉组和不锈钢锉组，每组32颗牙，分别将机用ProTaper镍钛根管锉和不锈钢K锉折断于根管内，超声法取折断根管锉，计算取出率，并使用图像分析软件分析术前、术后数字x线片的根管面积变化。结果不锈钢锉取出率大于镍钛锉，根管壁切削量也大于镍钛锉，但差异无统计学意义（P〉0．05）。折断根管锉断端暴露长度小于1．5mm时81％镍钛锉可取出，不锈钢锉约为47％，差别有统计学意义（P〈0．05）。结论超声法可有效取出根管内镍钛和不锈钢根管锉。取不锈钢锉需暴露的断端长度大于镍钛锉；2种根管锉采用超声法取出时根管壁切削量无显著差异。

Comparison of removing nickel-titanium and stainless-steel broken files from root canal by ultrasonic technique in vitro

Objective To compare the success rates and dentine removal amount of removing nickel-titanium and stainless-steel broken files from root canal by ultrasonic technique in vitro. Methods Sixty-four extracted mandibular incisors were divided equally into two groups with either broken nickel titanium （NiTi） files or stainless-steel （SS） K- files. Broken files were removed using ultrasonic tips combined with dental operating microscope. The number of successful case in each group was recorded. Pre-/postoperative digital radiographs were analyzed by image analyzing software to calculate the amount of dentine removed. Results The success rate of SS group was higher than that of NiTi group but the difference was not significant （ P 〉 0. 05 ）, and neither was the difference of dentine removal amount. When the exposed length was shorter than 1.5mm, 81% of NiTi files and 47% of SS files were successfully removed（ P 〈 0. 05）. Conclusion Operational microscope combined with ultrasonic technique is an effective and safe method in removing broken files and the exposed length necessary for the removal is longer in SS file than in NiTi file.