A Study as to How the Shape of Curved Root Canal After Preparation Exerts Influence on Lateral Condensation

本研究的目的是为了阐明在弯曲根管上实现紧密根管清扫所需的因素。在实验中，通过改变根管的直径、锥度和曲率来制备透明根管模型。横向冷凝采用不锈钢扩散器（SS）和镍钛扩散器（NT）。在根管模型表面评价杜仲胶点的凝结情况。对于弯曲根管且根管准备不充分的情况，也采用相同的方法评估侧缩的填充情况。根管直径的影响：发现根管厚度（直径）对根管尖端方向的封闭器的剩余状态有影响。2.粗根管在SS和NT两种情况下更容易插入根管深度，根管尖端的胶泊胶点更容易凝结。根管影响更大：在根管锥度较低的模型中，SS和nt的大部分封闭剂都停留在根管尖端的根管壁上。当根管锥度增加时，扩展器可以插入到根管深度，并且可以提供更好的凝结效果。这有助于减少封闭剂在根管壁上的残留量。NT的充填条件略差于SS，这可能是由于NT的直径比SS稍厚，其根管插入性能较差，且其柔韧性起反作用，不能达到充分的凝聚。3 .根管曲率的影响：在SS和NT中，根管曲率对充填条件的影响似乎较小，但在使用NT时，根管曲率对扩展器插入性能的影响较小。根管预备形状不充分对根管的影响：根管预备不充分时，根管壁上根据预备方法的不同，观察到不同类型的切痕。这部分封口剂残留较多，杜仲胶点凝结不足。在拉链处观察到根管尖端外曲线被过度切割，根管尖因铺布器的堵塞作用而出现弯曲现象。这些结果表明，对于弯曲的根管，在根管预备时要有足够的锥度，以达到满意的根管填充。少

The persent study was designed with the purpose of elucidating the factors necessary for achieving close and tight root canal swaling on the curved root canal. For the experiment, transparent root canal models were prepared by varying diameter, taper and curvature of the root canal. For lateral condenstation, stainless stell spreader (SS) and nickel-titanium spreader (NT) were used. Condensation of gutta-percha point was evaluated on the surface of root canal model. For the case of curved root canal with inadequate root canal preparation, the filling situation of lateral condensation was also evaluated by the same procedure.1. Influence of root canal diameter : It was found that the thickness (diameter) of root canal gave influence on the remaining condition of the sealer in the direction toward root canal tip. Thick root canal could be more easily inserted to the depth of root canal in both SS and NT, and condensation of gutta-percha point at root canal tip could be easily achieved.2. … More Influence of root canal : In a model with lower root canal taper, much of the sealer remained on root canal wall at root canal tip in both SS and NT.When the root canal taper was increased, it was possible to insert the spreader to the depth of root canal and it provided better effect on condensation. This contributed to the decrease of the amount of the sealer remaining on root canal wall. Filling condition was somewhat poorer in NT than SS.This may be attributed to the fact that NT showed poorer performance of insertion into root canal because it was slightly thicker in diameter than SS and also that its flexibility exerted reverse effect and sufficient condensation could not be attained.3. Influence of curvature of root : It appeared that the curvature of root canal exerted less influence on the filling condition in both SS and NT.However, when NT was used, there was less difference in the performance of insertion of the spreader due to the curvature.4. Influence of the inadequate shape of root canal preparation : In case of root canal with inadequate root canal preparation, different types of cutting marks were observed on root canal wall depending on the types of preparation methods. Sealer remained much on this part, and condensation of gutta-percha point was insufficient. On the zip, excessive cutting on outer curve of root canal tip, meander phenomenon of the point due to plugger effect of the spreader was observed.These results suggest that, in case of curved root canal, it is important to give adequate taper in root canal preparation for the purpose of achieving satisfactory root canal filling. Less