title: The treatment timing of labial inversely impacted maxillary central incisors: A prospective study.
abstract: OBJECTIVE
  To determine the timing of treatment for the labial inversely impacted maxillary central incisors.
  
  
  METHODS
  Twenty-eight patients (mean age, 8.2 years) with labial inversely impacted maxillary central incisors were divided into early-treated and later-treated groups according to their dental age. All of the patients were treated with a combination of surgery and orthodontic traction using the Guide rod appliance. Cone-beam computed tomography images were taken immediately after treatment for assessing the root morphology, root length, and alveolar bone loss. Sagittal slices were evaluated at the widest labial-lingual width of the tooth in the axial view. All variables were evaluated by Simplant 13.0 software (Materialise Dental NV, Leuven, Belgium).
  
  
  RESULTS
  The rank sum test indicated that the root length of two groups showed a statistically significant difference between the impacted and homonym tooth, with a shorter length in the impacted tooth (P < .05). The D-value (difference of root length between the impacted and homonym tooth) and alveolar bone loss on the labial side of the impacted incisor are significantly less in the early-treated groups when compared with the later-treated groups (P < .05). Spearman rank correlation analysis showed a statistically positive association between the treatment timing and D-value (r  =  .623, P < .05). The chi-square test for morphology of root apex indicated that the incidence of the root-apex-directed labial side is significantly higher in the later-treated groups when compared with the early-treated groups.
  
  
  CONCLUSIONS
  The labial inversely impacted maxillary central incisors should be treated early to promote root development by achieving a better morphology of root apex, thus reducing the risk of alveolar bone loss on the labial side.
authors.affiliation: a  Resident Doctor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: b  Professor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Rongdang
authors.initials: R
authors.lastname: Hu
authors.affiliation: c  Postgraduate Student, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Manman
authors.initials: M
authors.lastname: Ren
authors.affiliation: d  Attending Physician, Department of Stomatology, People's Hospital of Lishui, Lishui, Zhejiang, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.affiliation: a  Resident Doctor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Xiuying
authors.initials: X
authors.lastname: Wang
authors.affiliation: a  Resident Doctor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Chaofan
authors.initials: C
authors.lastname: Sun
authors.affiliation: a  Resident Doctor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D002648:Child; D054893:Cone-Beam Computed Tomography; D006801:Humans; D007180:Incisor; D008437:Maxilla; D011446:Prospective Studies; D014092:Tooth Root; D014095:Tooth, Impacted / Q000628:therapy*
keywords: CBCT; Central incisor; Labial inversely impacted tooth; Treatment timing