Clinical Study Of Adjustable Movable Retractor For Maxillary Labially Inverted Impacted Central Incisor

Objective To evaluate the orthodontic treatment outcome in patients with labially inversely impacted maxillary central incisor with adjustable movable tractorMethods Ten patients,aged 7 to 10 years,with labially inversely impacted maxillary central incisor were treated orthodontically.The Cone-beam computed tomography(CBCT)was taken before treatment and after treatment to evaluate the root length,root canal wall thickness,the apical foramen width,alveolar bone height and thickness.The periodontal and endodontic conditions were evaluated.The parameters of the treated incisors and contralateral ones served as controls were compared.Results The success rate of treatment in 10 patients was 100%.The impacted teeth had no loosening,no gingival swelling,no gingival redness,periodontal pockets,and pulp necrosis.However,the labial gingival height of the treatment group(10.58±0.45)mm was slightly higher than that of the control group(9.47±0.31)mm(P<0.01).The growth and development level of the treatment group was higher than that of the control group during traction.The change in root length(2.80±1.09)mm and the change in apical foramen(1.79±0.59)mm of the treatment group were higher than those in the control group(1.84±0.97)mm and(0.96±0.40)mm,and the apical foramen had a significant statistical difference between the two groups(P<0.01).Before treatment,the root growth of the treatment group was retarded.The root length of the treatment group(7.28±1.03)mm was shorter than that of the control group(9.80±1.46)mm(P<0.01),and the apical foramen width in the treatment group(2.18±0.63)mm was larger than that in the control group(1.26±0.40)mm(P<0.01).After treatment,the root length(10.08±0.63)mm of the treatment group was still shorter than that of the control group(11.75±0.90)mm(P<0.01),and the labial alveolar bone level of the treatment group(1.77±0.37)mm was higher than that of control group(1.25±0.26)mm(P<0.01).The palatal alveolar bone level of treatment group(1.23±0.21)mm was also higher than that of the control group(1.05±0.15)mm(P<0.05).The thickness of the alveolar bone in the treatment group(1.49±0.31)mm was thinner than that in the control group(1.80±0.11)mm(P<0.01).No significant differences was found in the pulp electrical activity test value,gingival index,periodontal exploration depth,palatal gingival height,labial and palatal root canal wall thickness and their changes,the apical foramen width after treatment,the changes of root length and root canal wall thickness between the treatment group and the control group(P>0.05).Conclusions Orthodontic therapy for labially inversely impacted maxillary central incisor by adjustable movable tractor could promote root development and alveolar bone remodeling.Good periodontal and endodontic conditions were achieved.