根管弯曲度对根管锉疲劳寿命的影响

目的 研究根管弯曲角度和弯曲半径对根管锉的致损作用.方法 采用自制模拟根管弯曲角度和半径的不锈钢管模型,用M4回旋手机(4000rpm)驱动不锈钢K锉,用16∶1减速手机(500rpm)驱动Hero642镍钛锉,共4种型号器械各12支,测定锉针在钢管模型中旋转至折断所需时间.结果 ①根管弯曲半径较小时,根管锉折断所需时间较短(P＜0.05);根管弯曲角度较大时,根管锉折断所需时间较短(P＜0.05).②在同一根管模型中,不锈钢K锉直径较细的容易折断(P＜0.05);镍钛锉直径较粗的容易折断(P＜0.05).结论 ①根管弯曲角度越大,根管弯曲半径越小,根管锉折断所需时间越短,即越容易折断;②锉针粗细的变化对不锈钢锉与镍钛锉抗弯曲折断的影响是不同的.

The effect of root canal curvature on fatigue of root canal files

Objective To evaluate the effects of root canal curvature on root canal files fatigue.Methods The fatigue of stainless steel K (SSK) files and Hero642 NiTi files was evaluated with stainless steel curved root canal models.Results The files were fractured more quickly in canal models of the same curvature degree but with smaller curve radius (P<0.05). The files were fractured more quickly in canal models of the same curve radius but with greater curvature degree (P<0.05). SSK files with smaller diameter were fractured more easily (P<0.05). On the contrary, NiTi files with greater diameter were fractured more easily (P<0.05).Conclusion Curve radius and curvature degree had strong influence on the life of files. SSK files with smaller diameter and NiTi files with greater diameter were fractured more easily.