title: Root morphology and development of labial inversely impacted maxillary central incisors in the mixed dentition: a retrospective cone-beam computed tomography study.
abstract: BACKGROUND
  The aim of this study was to analyze 3-dimensional data of root morphology and development in labial inversely impacted maxillary central incisors.
  
  
  METHODS
  Cone-beam computed tomography images from 41 patients with impacted incisors were divided into early and late dental age groups according to their dental age. Sagittal slices in which the labiolingual width of the tooth was the widest in the axial view were evaluated. The inverse angle, the dilaceration angle, and the length of both impacted and homonym teeth were evaluated with SimPlant Pro software (version 13.0; Materialise Dental NV, Leuven, Belgium).
  
  
  RESULTS
  The Student t test indicated that the lengths of the impacted teeth were significantly shorter than those of the homonym teeth (P <0.05), and the root lengths of the early dental age group were significantly shorter than those of the late dental age group. The results from chi-square tests indicated that the incidence of dilacerations was significantly higher in the late dental age group when compared with the early dental age group. Multiple regression analyses indicated that the independent variables for root length of the impacted teeth were dental age (β = 0.958; P <0.001) and length of the nondilacerated part of the root (β = 0.435; P <0.001).
  
  
  CONCLUSIONS
  Dilaceration was more common in the late dental age group. The roots of labial inversely impacted maxillary central incisors continue developing, but their potential is limited.
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Chaofan
authors.initials: C
authors.lastname: Sun
authors.affiliation: Professor, Department of Orthodontics, James Cook University, Cairns, Queensland, Australia.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Ye
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Dai
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Xiuying
authors.initials: X
authors.lastname: Wang
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Qingchao
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Sisi
authors.initials: S
authors.lastname: Pan
authors.affiliation: Professor, Department of Orthodontics, School of Stomatology, Wenzhou Medical University, Wenzhou, Zhejiang, China. Electronic address: hurongdang@hotmail.com.
authors.forename: Rongdang
authors.initials: R
authors.lastname: Hu
mesh_terms: D000366:Age Determination by Teeth; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000254:growth & development; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging*; D009805:Odontogenesis / Q000502:physiology; D009811:Odontometry / Q000379:methods; D010159:Palate / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D012984:Software; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000254:growth & development; D019237:Tooth Cervix / Q000000981:diagnostic imaging; D019228:Tooth Crown / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000254:growth & development; D014095:Tooth, Impacted / Q000145:classification / Q000000981:diagnostic imaging*