三种运动方式对TF单根镍钛器械在磨牙弯曲根管预备能力的比较研究

The comparison of TF Nickle- Titanium instruments with different operation mode in the preparation of curved root canal of molars

目的：比较3种不同运动方式下TF镍钛系统单根锉预备根管的能力。方法：收集临床新鲜拔除的上、下颌磨牙（弯曲度20°~35°）90个（含根管105个）,并将其随机分为3组（n=30个牙,35个根管）：A组为连续旋转500 r/min、B组为往复旋转300 r/min、C组为连续旋转300 r/min;设定机用马达恒定扭矩3 N·cm,用TF镍钛锉（#25/06）冠向下技术对各组根管进行预备;CBCT拍摄3组根管预备前后的横截面影像,测定根管偏移量和定心比率值,并比较各组根管预备所需时间,显微镜观察各组器械的损耗情况。结果：3组根管预备后,在根管中下段,根管偏移量A组最小、B组最大（P〈0.05）;定心比率值C组较好、B组较差（P〈0.05）;在根尖和根管中上段两者较一致（P〉0.05）;B组预备根管的时间长于A、C组（P〈0.05）;B组使用寿命约是A、C组的2倍。结论：TF单根锉（#25/06）配合往复旋转运动模式行根管预备时,用时相对较长,但其安全性也更高;在300、500 r/min连续旋转速度下的操作效果无明显差异。

AIM： To evaluate the endodontic preparation ability of single TF nickel-titanium instrument with different operation mode in the preparation of curved root canal. METHODS： 90 intact molars with 105 root canals were divided into 3 groups（ n = 30 molars with 35 canals）,the canals of the molars were prepared by the instrument with continuous rotation at 500 r / min（ group A）,reciprocating movement at 300 r / min（ group B） and continuous rotation at 300 r / min（ group C） respectively. The CBCT images of the root canal sections were recorded,the root transportation and centering ratio were measured before and after instrumentation. The preparation time,wearing and tearing degree of the instrument were compared. RESULTS： At 3. 0 mm from the anatomic apex,root transportation of group B was significantly greater than that of group A（ P〈0. 05）,centering ratio of group C was significantly better than that of group B（ P〈0. 05）. There was no significant difference in root transportation and centering ratio among 3 groups at the distances of 1. 5 mm and 6 mm from the anatomic apex. The preparation time of group B was significantly longer than that of group A and C（ P〈0. 05）. The lifespan of group B was about 2 times of group A and C. CONCLUSION： TF single nickel- titanium instrument（ #25 /06） used with reciprocating mode may produce lower efficiency but higher security. When it is used with continues rotation mode,there is no significant difference between the speeds of 300 r / min and 500 r / min except that the speed of 300 r / min may shorten the lifespan of the instrument.