TF和S3预备磨牙重度弯曲根管的效果评价

Evaluation of the effects of TF and S3 nickel-titanium instruments in severely curved molar root canal preparation

目的:比较Twisted File(TF)、萨尼S32种机用镍钛锉预备重度弯曲根管的成形效果及牙根微裂情况。方法:按照Schneider测量法,选取近颊(MB)根管弯曲度>25°的60颗上颌磨牙,随机分为TF组(n=30)和S3组(n=30),2组均采用冠向下法预备根管,预备前后进行锥形束CT(cone-beam CT,CBCT)扫描,记录距离根尖孔3、5、7 mm处根管偏移值。所有离体牙在距根尖顶点3、5、7 mm处垂直牙体长轴做横切片,显微镜下观察并记录牙根裂纹形成情况,评估TF、S3镍钛锉的根管预备效果。采用SPSS 19.0软件包对数据进行统计学分析。结果:所有根管均存在偏移,TF组和S3组在距离根尖孔3 mm处偏移有统计学差异(P<0.05),TF组牙根微裂发生率为20%(6/30),TF组牙根微裂发生率为13.3%(4/30),2组间牙根裂纹发生率差异无统计学意义(P>0.05)。结论:在离体牙重度弯曲根管预备中,TF和S3均有微裂纹产生,S3较TF能更好地维持根管原有走向。

PURSPOSE: To compare the shaping ability and dental cracks of Twisted File and S3 in severely curved molar root canal preparation. METHODS: Sixty extracted mandibular molars with mesiobuccal canals(canal curvature angles beyond 25°) were selected and divided randomly into 2 groups with 30 canals in each group. The canals were scanned by cone-beam CT(CBCT) before and after root canal preparation.The canal transportation was recorded at 3 points(3, 5, 7 mm to root tip). After root canal preparation,all the roots were horizontally sectioned 3,5 and 7 mm from the apex. The slices were observed under optical stereomicroscope. SPSS 19.0 software package was used for statistical analysis. RESULTS: Transportations occurred in all groups. No significant difference was found between the two groups of canal transportation at the two points(5 mm and 7 mm to root tip)(P>0.05);at the point of 3 mm to the root tip,the transportation of canals prepared by S3 was obviously lesser than the canals prepared by TF. There was no significant difference in the incidence of dentinal cracks between the two groups(P>0.05). CONCLUSIONS: Under the conditions of severely curved molar root canal in extracted teeth, cracks were found in both groups, S3 was found to be better in maintaining original canal shape than TF system.