To investigate the effect of orthodontic traction on root and periodontal tissues of impacted anterior teeth with developed or underdeveloped roots.

This was a retrospective study. The clinical data of 102 patients (108 anterior teeth in total) who underwent orthodontic traction at Taizhou Hospital of Traditional Chinese Medicine from June 2017 to January 2020 were selected. According to the root development status, the patients were divided into a complete root development group (54 anterior teeth) and an incomplete root development group (54 anterior teeth). There were 28 males and 23 females in the complete root development group, with an average age of (16.22±6.54) years. There were 29 males and 22 females in the incomplete root development group, with an average age of (16.54±6.60) years. Both groups were treated by orthodontic traction. The teeth treated by orthodontic traction were regarded as treatment teeth, and the untreated teeth of the same jaw and the same name (54 anterior teeth) were regarded as control teeth. Root indexes (root length, root wall thickness, root curvature rate, and pulp vitality) and periodontal tissue indexes (attached gingival width and labial bone plate thickness) before and after orthodontic traction were recorded and compared among the groups.

In the incomplete root development group, the root length and root wall thickness after traction were significantly higher than those before traction [(13.27±2.24) mm vs (12.28±2.18) mm, (2.53±0.25) mm vs (2.10±0.16) mm, P＜0.05 for both]. In the fully developed group, the root length was (11.03±2.02) mm, which was significantly lower than that before traction [(12.01±2.11) mm] and that of control teeth [(13.22±1.23) mm], and the root wall thickness was (2.20±0.19) mm, which was significantly lower than that of control teeth [(2.52±0.24) mm] (P＜0.05 for all). After traction, the root length and root wall thickness of the complete root development group were (11.03±2.02) mm and (2.20±0.19) mm, respectively, both of which were significantly lower than those of the incomplete root development group [(13.27±2.24) mm, (2.53±0.25) mm] (P＜0.05 for both). The root length of the control group with complete root development was significantly lower than that of the control group with incomplete root development [(13.22±1.23) mm vs (13.80±1.55) mm, P＜0.05]. After traction, the width of attached gingiva and the thickness of the labial bone plate were significantly lower than those before traction in all the three groups (P＜0.05 for all). The width of the attached gingiva and the thickness of the labial bone plate in the incomplete root development group were significantly larger than those of the complete root development group (P＜0.05 for both). The thickness of the labial bone plate in the control group with complete root development was significantly lower than that of the control group with incomplete root (P＜0.05).

Orthodontic traction for impacted anterior teeth with underdeveloped roots is associated with rapid periodontal tissue reconstruction, short orthodontic traction time, and mild root absorption.