三种方法预备下颌第二磨牙C形根管成形效果的比较

目的 评价3种常用根管预备方法对C形根管的成形效果,为临床治疗提供参考.方法 对临床拔除的具有C形根管的下颌第二恒磨牙60颗,应用改良Bramante技术,于距根尖2mm、5 mm和8mm处将牙根横断.选择手用不锈钢K锉逐步后退技术(Step-Back组)、逐步深入技术(Step-Down组)和机用旋转镍钛锉ProTaperTM系列冠向下预备技术(Crown-Down组)预备不同类型的C形根管,比较预备前后根管横截面形态的数码图像,对3种不同方法的成形效果进行评价.结果 3种方法预备离体下颌第二磨牙C形根管后均有遗漏.不锈钢K锉逐步后退技术和不锈钢K锉逐步深入技术分别在根冠部遗漏面积百分比分别为(0.177±0.071)%、(0.068±0.074)%]和根尖部遗漏面积百分比分别为(0.236±0.167)%、(0.295±0.171)%]遗漏较少(P＜0.05).CⅠ、CⅡ型遗漏出现在近远中多于颊舌侧,将其分为独立的2～3个根管预备可减少遗漏.不同方法预备根尖区的遗漏均显著高于根管中上部(P＜0.05).结论 早期开敞根管上段,将C形根管分为2～3个独立的根管进行预备,可以增进根管预备的成形效果.

Comparative study of shaping efficiency in C-shaped canals of mandibular second molars

OBJECTIVE: To investigate the shaping efficiency of three instrumentation techniques in the C-shaped canals. METHODS: Sixty extracted mandibular second molars with C-shaped canals were selected and cross-sectioned at 2, 5, 8 mm from the apex by using a muffle system as described by Bramante. The teeth containing C-shaped canals were randomly divided into three groups, respectively instrumented using stainless steel K-files in step-back and step-down techniques, and ProTaper series in crown-down technique. The digital images of canal cross-sections pre- and post-instrumentation were photographed to evaluate the proportion and position of uninstrumented area Working length loss and perforation were recorded. Data were analyzed using ANOVA. RESULTS: Step-down technique gained smaller uninstrumented area in the coronal third of the canals, while step-beck technique gained the same results in the apical third (P < 0.05). Uninstrumented proportion in apical part was significantly higher than in the middle and the coronal (P < 0.05). Instrumenting type I canal as 2 or 3 separated canals was likely to reduce the miss. There were three perforations in manual stainless steel K-file groups. CONCLUSIONS: Early opening the coronal part of C-shaped canal, shaping C-shaped canal as two or three separated canals and instrumenting the apical part with step-back technique, seemed to be the effective methods to avoid miss.