不同镍钛根管预备系统对牙本质裂纹形成的影响

Effects of different nickel-titanium root canal preparation systems on the dentin crack formation

目的探讨不同镍钛旋转预备系统ProTaper Universal (PU)、ProTaper Next(PN)和X+File(X+)对牙本质微裂纹形成的影响。方法将100颗下颌前磨牙随机分为4组(n=25)。组1为对照组(不做根管预备);组2为PU预备组(SX预备根管口,S1、S2、F1、F2预备直达工作长度);组3为PN预备组(Protaper Universal SX预备根管口,再用ProTaper Next X1、X2预备直达工作长度)。组4为X+预备组(Protaper Universal SX预备根管口,然后用X+File X1、X2预备直达工作长度)。预备完成后,所有离体牙在距根尖顶点3mm、6mm和9mm处垂直于牙体长轴做横切片,在根管显微镜下观察并记录裂纹形成情况。卡方检验对裂纹形成数目进行统计分析。结果对照组未产生牙本质裂纹。镍钛旋转系统PU、PN和X+的牙本质裂纹发生率分别为60%,32%和24%(P<0.05)。仅PU组产生完全裂纹,且数目高于另外3组(P<0.05)。在根尖1/3处,PU组的不完全裂纹数高于另外3组(P<0.05)。PN组和X+组的牙本质裂纹发生率无明显差异(P>0.05)。结论本研究中使用的3种镍钛根管预备系统均产生了牙本质裂纹。其中,X+File与ProTaper Next产生的牙本质裂纹较少,这可能与镍钛金属结构、尖端设计以及中心定位能力有关。

Objective The effects of different nicel-titanium rotary systems of ProTaper Universal （PU）, ProTaper Next （PN） and X＋File （X＋） on dentin cracs formation were investigated. Methods One-hundred man-dibular premolars were chosen and divided into 4 groups randomly （n=25）. Gr 1 was as control group （no prepara-tion）; Gr 2 was as PU preparation group （the coronal one-thirds of the canals were prepared with Sx and S1, S2, F1 and F2 instruments were used for the woring length）; Gr 3 was as PN preparation group （the coronal one-thirds of the canals were prepared with Sx and X1, X2 were used for the woring length）; Gr 4 was as X＋ preparation group （the coronal one-thirds of the canals were prepared with Sx and X1, X2 were used for the woring length）.All the prepared roots were horizontally sectioned at 3mm, 6mm and 9 mm from the apex. The cracs were ob-served by endodontic microscope. The cracs formation was recorded and analyzed with a Chi-square test. Results No dentin crac was observed in the control group. The incidences of dentin crac formation in different nicel-titanium rotating systems of PU,PN and X＋ were 60%, 32% and 24% respectively. Only complete cracs were observed in PU group and the number was higher than that in three other groups （P〈0.05）. At 3mm level, the num-ber of incomplete crac in PU group was higher than that in three other groups （P〈0.05）. There was no signifcant difference in the incidence of dentin crac formation between PN group and X＋ group （P〉0.05）. Conclusion All three different nicel-titanium rotating systems of PU, PN and X＋ used in this study caused dentin crac formation. Among them, X＋File and ProTaper Next produced fewer dentin cracs. Niceltitanium structure, tips design and central location capability may be the reason for the less dentin crac.