乳磨牙根管口部形态的增龄变化研究

Morphologic study of the root canal orifices in human mandibular primary molars

目的 研究下颌乳磨牙根管口部形态的增龄变化。方法 选取 3～ 8岁患儿 86颗诊断为牙髓炎症的下颌乳磨牙 ,拍摄X线牙片 ,失活、揭髓顶、拔髓、清洗根管后 ,取根管口部形态印像 ,制作树脂模型。在牙轴与髓室底最高点相交处下方 0 .5mm～ 1.0mm处制作两枚切片 ,用计算机进行分析测量 ,按年龄分成 3组进行研究。结果 下颌第一乳磨牙近中根管口部宽度明显大于远中根管 ,第二乳磨牙则相反。X线牙片测量值大于树脂切片测量值。根管口部长度测量显示第一乳磨牙近中根管口小于远中根管口 ,而第二乳磨牙近远中根管长度近似。下颌第一、二乳磨牙近中根管口面积都小于远中根管。第一、二乳磨牙髓室底厚度都有随年龄增长而增厚趋势。结论 本研究结果对乳牙牙髓和根管治疗 ,特别对活髓切断术器械选择 。

Objective To study the morphology of the root canal orifices in human mandibular primary molars.Methods Using 86 human mandibular primary molars within an age range of 3～8 years. After a dental X-ray was taken, and following removal of the roof of pulp chamber and pulpectomy, a silicone impression of the pulp orifice was obtained directly from the primary molars. By this means, an epoxy-resin replica was made and sliced at two points: 0.5 and 1.0mm from the pulpal floor respectively. Several variables were considered for the morphometric study of the pulp orifice such as width, length, area, frequency and size of the concavity at the selected levels. The samples were dlivided into three groups according to age in order to find out any influence according to age.Results The width of the pulp orifices in first primary molars showed a greater value at the mesial root than at the distal root, while in the second molars it was just the opposite. The values obtained by measuring the X-ray films were slightly greater than those obtained from the resin models. The length in the first primary molar showed a smaller value at the mesial root than at the distal root, while in the second primary molar the two values were similar. The area in both first and second primary molars was smaller at the mesial root than at the distal one. With regard to the influence of age, the thickness of the floor of the pulp chamber increased in both first and second molars.Conclusion The obtained data in this study are of great importance when selecting the size of the instrument during endodontic therapy specially while pulpectomy is undertaken.