title: Emergence angles of the cementoenamel junction in natural maxillary anterior teeth.
abstract: BACKGROUND
  Fabrication of normal crown contour to maintain gingival health is difficult in the absence of emergence angle data.
  
  
  OBJECTIVE
  The aim of this study was to measure the geometric values of the emergence angles on the cementoenamel junction (CEJ) for natural maxillary anterior teeth.
  
  
  METHODS
  This study collected 148 natural permanent maxillary anterior teeth (74 central incisors, 59 lateral incisors, and 15 canines) with intact cervixes for this study. The teeth were scanned with a three-dimensional (3D) scanner to construct 3D models. This study measured the emergence angles of the cervical CEJ on the zenith of labial, palatal, mesial, and distal, for each tooth.
  
  
  RESULTS
  Measurements made on 148 maxillary anterior teeth showed the emergence angle to be within a narrow range from 11.30° to 15.26°, irrespective of the tooth location. There were no statistically significant differences between any two groups (p > 0.05).
  
  
  CONCLUSIONS
  On the basis of measurements taken from natural teeth, we conclude that the emergence angles of the CEJ in natural maxillary anterior teeth should be 15° from the root surface.
  
  
  CONCLUSIONS
  The information presented in this article may be useful in helping to create dental restorations with optional emergence angles over the CEJ in natural maxillary anterior teeth. Prior to the treatment the dentist should consider not only the fit of the crown, but also the emergence angles and contours of the soft tissues surrounding the involved teeth.
authors.affiliation: Division of Prosthodontics, Department of Dentistry, Kaohsiung Medical University Hospital, 100 Shih-Chen 1st Road, Kaohsiung, Taiwan. dujekang@ms31.hinet.net
authors.forename: Je-Kang
authors.initials: JK
authors.lastname: Du
authors.forename: Hung-Yuan
authors.initials: HY
authors.lastname: Li
authors.forename: Ju-Hui
authors.initials: JH
authors.lastname: Wu
authors.forename: Huey-Er
authors.initials: HE
authors.lastname: Lee
authors.forename: Chau-Hsiang
authors.initials: CH
authors.lastname: Wang
mesh_terms: D003481:Cuspid / Q000033:anatomy & histology; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008437:Maxilla; D009811:Odontometry / Q000379:methods*; D019237:Tooth Cervix / Q000033:anatomy & histology*