title: Identification of a stable reference area for superimposing mandibular digital models.
abstract: OBJECTIVE
  The purpose of this retrospective study was to assess the stability of buccal and lingual alveolar bone surfaces for superimposing three-dimensional (3D) digital models of dental casts.
  
  
  METHODS
  The pre- and posttreatment dental casts and lateral cephalometric radiographs were obtained from 10 adult patients who had undergone orthodontic treatment entailing the extraction of four premolars. Five of them had bilateral mandibular tori and the other 5 patients had no torus. Dental casts were scanned with a three-dimensional (3D) surface scanning system and 3D digital models were reconstructed using 3D reverse modeling software. The pre- and posttreatment digital models were superimposed on the following reference areas by the best-fit method: Area 1, bilateral lingual surfaces of the alveolar process of the posterior teeth; Area 2, the lingual alveolar surface of the anterior and posterior teeth; Area 3, bilateral surfaces of the posterior teeth's buccal and lingual alveolar surfaces; Area 4, bilateral mandibular tori. The horizontal and vertical movements of the mandibular central incisors and first molars were measured on cephalometric radiographs and on the 3D digital models.
  
  
  RESULTS
  In the 5 patients without a mandibular torus, the median differences between cephalograms and 3D digital models ranged from 0.8-1.9 mm and the maximum differences from 1.5-10.0 mm. The median and maximum differences between cephalograms and 3D digital models superimposed on Area 2 were greater than those superimposed on Areas 1 and 3. In the patients with mandibular tori, the median differences between cephalograms and 3D digital models were under 1.0 mm, the maximum difference being 0.7 mm.
  
  
  CONCLUSIONS
  The buccal and lingual alveolar surface near the dentition seems to be inappropriate as a reference area for superimposing 3D mandibular digital models of patients without a mandibular torus. Mandibular tori in adult patients are stable structures which can be used as reference areas for the superimposition of 3D mandibular digital models.
authors.affiliation: Department of Orthodontics, College of Dentistry, Gangneung-Wonju National University, 120, Gangneung Daehangno, 210-702, Gangneung, Korea.
authors.forename: Kiyong
authors.initials: K
authors.lastname: An
authors.affiliation: Department of Orthodontics, College of Dentistry, Gangneung-Wonju National University, 120, Gangneung Daehangno, 210-702, Gangneung, Korea.
authors.forename: Insan
authors.initials: I
authors.lastname: Jang
authors.affiliation: Department of Orthodontics, College of Dentistry, Gangneung-Wonju National University, 120, Gangneung Daehangno, 210-702, Gangneung, Korea.
authors.forename: Dong-Soon
authors.initials: DS
authors.lastname: Choi
authors.affiliation: Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Paul-Georg
authors.initials: PG
authors.lastname: Jost-Brinkmann
authors.affiliation: Department of Orthodontics, College of Dentistry, Gangneung-Wonju National University, 120, Gangneung Daehangno, 210-702, Gangneung, Korea. korth@gwnu.ac.kr.
authors.forename: Bong-Kuen
authors.initials: BK
authors.lastname: Cha
mesh_terms: D000293:Adolescent; D000328:Adult; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D003735:Dental Casting Technique; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods / Q000592:standards; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008875:Middle Aged; D003765:Models, Dental; D023861:Photography, Dental / Q000379:methods* / Q000592:standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000592:standards; D055815:Young Adult
keywords: Mandible; Mandibular torus; Superimposition; Three-dimensional digital models; Tooth movement