[Clinical study of a adjustable movable retractor for maxillary labially inverted impacted central incisor]

To evaluate the orthodontic treatment outcome of a new adjustable movable retractor for patients with maxillary labially inverted impacted central incisors.

Ten patients, aged 7 to 10 years, who had a maxillary labially inverted impacted central incisor, were treated using a new adjustable movable retractor. Cone-beam CT(CBCT) was taken before treatment and after treatment immediately. Pulp electrical activity test and periodontal probing were performed after treatment. The parameters of the treated incisors and contralateral ones served as controls were compared.SPSS 23.0 software package was used for data analysis. RESULTS： The success rate of treatment in 10 patients was 100%. The mean duration of treatment was（8.60±1.26） months. There were no loosening, gingival swelling and redness, periodontal pockets, and pulp necrosis in the treatment group. However, the labial gingival height of the treatment group was (10.58±0.45) mm, significantly higher than that of the control group [(9.47±0.31) mm]. The growth and development level of the treatment group was higher than that of the control group during traction. The root length[(2.80±1.09) mm] and apical foramen [(1.79±0.59) mm] of the treatment group were higher than those of the control group[(1.84±0.97) mm and (0.96±0.40) mm]. 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]; meanwhile, the apical foramen width of the treatment group[(2.18±0.63) mm] was larger than that of the control group[(1.26±0.40) mm]. 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]. 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]. The palatal alveolar bone level of treatment group[(1.23±0.21) mm] was also slight higher than that of the control group[(1.05±0.15) mm]. 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]. CONCLUSIONS： The effect of the new adjustable movable retractor for maxillary labially inverted impacted central incisor is reliable. Traction therapy can promote root development, and the periodontal and endodontic condition is well after treatment.