Daito M, Kawahara S, Kato M, Okamoto K, Imai G, Hieda T
Department of Pedodontics, Osaka Dental University.
J Osaka Dent Univ. 1991 Apr;25(1):1-23.
In order to construct standardized charts for root resorption in the primary dentition of Japanese children, we investigated the stages of resorption (1/4, 1/2 and 3/4 of the root) based on the criterion of Fanning, et al. using 11,167 panoramic radiographs (5,759 of boys and 5,408 of girls). The following information was obtained. 1) The root resorption for a tooth on one side was the same as for its counterpart on the other side regardless of differences in sex or arch. 2) The average age for each root resorption stage was lower in girls than in boys regardless of differences in sex or arch. 3) The average age for each root resorption stage was lower in the mandible than in the maxilla for every tooth. 4) In the maxilla, the period between 1/4 to 3/4 resorption of the root was greater in the primary molars than in the primary anterior teeth. However, the opposite was true in the mandible. 5) Although no difference was observed between the maxilla and the mandible in the resorption period for the primary incisors and canines, the resorption time for the primary molars was greater in the maxilla than in the mandible. 6) When the relationship was observed between the resorption stages for each tooth and the calcification stages for the corresponding successional permanent tooth. a) With the exception of the maxillary and mandibular canines, the average age for 1/4 resorption of the primary root corresponded to the period between completion of the permanent crown and initial root formation of the successional permanent tooth. b) With the exception of the maxillary and mandibular canines, and the mandibular second premolars, the average age for 3/4 resorption of the primary root corresponded to the period between 1/4 and 1/2 formation of the root of the successional permanent tooth. From these results, standardized charts were constructed for the resorption of the roots of primary teeth in Japanese children. These standardized charts are useful in daily clinical practice in such areas as endodontic treatment of primary teeth and orthodontics.
为构建日本儿童乳牙牙根吸收的标准化图表，我们依据范宁等人的标准，对11167张全景X线片（男孩5759张，女孩5408张）进行研究，调查牙根吸收阶段（牙根的1/4、1/2和3/4）。得到以下信息：1）无论性别或牙弓差异，一侧牙齿的牙根吸收与其对侧对应牙齿相同。2）无论性别或牙弓差异，女孩各牙根吸收阶段的平均年龄低于男孩。3）每颗牙齿在下颌各牙根吸收阶段的平均年龄低于上颌。4）在上颌，乳磨牙牙根1/至3/4吸收阶段的时间比乳前牙长。然而，在下颌情况相反。5）虽然乳切牙和乳尖牙在上颌和下颌的吸收期无差异，但乳磨牙在上颌的吸收时间比下颌长。6）观察每颗牙齿的吸收阶段与相应继承恒牙钙化阶段的关系时，a）除上颌和下颌尖牙外，乳牙牙根1/4吸收的平均年龄对应继承恒牙冠完成至牙根开始形成的时期。b）除上颌和下颌尖牙以及下颌第二前磨牙外，乳牙牙根3/4吸收的平均年龄对应继承恒牙牙根1/4至1/2形成的时期。根据这些结果，构建了日本儿童乳牙牙根吸收的标准化图表。这些标准化图表在乳牙牙髓治疗和正畸等日常临床实践中很有用。
