title: Comparison of mandibular arch forms of Korean and Vietnamese patients by using facial axis points on three-dimensional models.
abstract: OBJECTIVE
  This study was aimed at comparing the mandibular arch forms of Korean and Vietnamese patients by using facial axis (FA) points on three-dimensional (3D) models.
  
  
  METHODS
  Mandibular casts of 68 Korean (Class I malocclusion, 30; Class II malocclusion, 38) and 78 Vietnamese (Class I malocclusion, 41; Class II malocclusion, 37) patients were scanned in their occluded positions and grouped according to arch form (tapered, ovoid, and square). The FA point of each tooth was digitized on the 3D mandibular models. The measurements and frequency distributions of the arch forms were compared between the ethnic groups.
  
  
  RESULTS
  The Vietnamese patients had significantly greater intercanine depth and intercanine and intermolar width-to-depth ratios than the Korean patients (p < 0.05). The frequency distributions of the arch forms were also significantly different (p = 0.038), but no sexual dimorphism was found.
  
  
  CONCLUSIONS
  Vietnamese people tend to have deeper and wider arches than Korean people. The three arch forms are evenly distributed in Korean people, but Vietnamese people frequently have square arches. Clinicians should identify the correct arch form of an ethnic group before initiating orthodontic treatment.
authors.affiliation: Graduate School of Clinical Dental Science, The Catholic University of Korea, Seoul, Korea.
authors.forename: Kil-Jun
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: Graduate School of The Catholic University of Korea, Seoul, Korea.
authors.forename: Vu Thi Thu
authors.initials: VT
authors.lastname: Trang
authors.affiliation: The Catholic University of Korea, Seoul, Korea. ; Department of Postgraduate Studies, Universidad Autonoma del Paraguay, Asuncion, Paraguay.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bayome
authors.affiliation: Postgraduate Orthodontic Program, Arizona School of Dentistry and Oral Health, A.T. Still University, Mesa, AZ, USA. ; Graduate School of Dentistry, Kyung Hee University, Seoul, Korea.
authors.forename: Jae Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Private Practice, Seoul, Korea.
authors.forename: Yong
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yoon-Ah
authors.initials: YA
authors.lastname: Kook
keywords: Arch form; Digital models; Ethnic norms; Korean; Vietnamese