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

本研究的目的是阐明弯曲根管达到封闭和紧密根管膨胀的必要因素。通过改变根管直径、锥度和弯曲度，制备透明根管模型。侧向冷凝采用不锈钢扩张器（SS）和镍钛扩张器（NT）。在根管模型表面观察牙胶尖的凝聚情况。对于弯曲根管预备不充分的病例，也采用同样的方法评价侧方加压的充填情况.根管直径的影响：发现根管厚度（直径）对根尖方向的残留情况有影响。结论：1. SS和NT组根管较粗更易插入根管深处，且根管尖端牙胶尖的凝聚更易消除. ...更多信息 根管治疗的注意事项在根管锥度较低的模型中，SS和NT的根管尖端有较多的牙釉质残留在根管壁上，当根管锥度增大时，可以将扩张器插入根管深处，对牙釉质的冷凝效果更好。这有助于减少残留在根管壁上的杂质。NT的充填情况略差于SS，这可能是由于NT的直径略大于SS，导致其插入根管的性能较差，同时NT的柔韧性起了相反的作用，不能达到充分的冷凝.根管弯曲度的影响：SS和NT的根管弯曲度对根管充填情况的影响较小，但NT的根管弯曲度对扩张器插入性能的影响较小.根管预备不充分对根管形态的影响：根管预备不充分的情况下，根管壁上观察到不同类型的切痕，这取决于预备方法的类型。该部位封闭剂残留较多，牙胶尖凝聚不足。结果表明，在弯曲根管的情况下，根管预备时应给予适当的锥度，以达到满意的根管充填效果。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