title: Effect of the inclination of a maxillary central incisor on periodontal stress: finite element analysis.
abstract: OBJECTIVE
  To determine the effect of labiolingual inclination of a maxillary central incisor on the magnitude and distribution of stresses within the periodontal space.
  
  
  METHODS
  Five three-dimensional finite element models of a right maxillary central incisor were created with 0°, 10°, 20°, 30°, and 40° inclination. Each incisor model was subjected to a 1 N lingual-directed force and 6-12 N·mm countertipping moment on the labial surface. The stress level within the periodontal ligament was calculated in terms of maximum principal stresses.
  
  
  RESULTS
  With increased inclination, compressive stresses tended to increase whereas tensile stresses tended to decrease. The location where compressive stress was prevalent changed from the midroot area to the apical area on the lingual side, while the area where tensile stresses were predominant changed from the midroot area to the cervical area on the labial side.
  
  
  CONCLUSIONS
  There are more compressive stresses concentrated at the apex of incisors with a high degree of inclination than in incisors that are more upright. This may be associated with the higher clinical incidence of apical root resorption found in inclined maxillary central incisors.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University, 34 Henri-Dunant Rd, Patumwan, Bangkok, Thailand, 10330. athicha99@gmail.com
authors.forename: Athicha
authors.initials: A
authors.lastname: Kanjanaouthai
authors.forename: Korapin
authors.initials: K
authors.lastname: Mahatumarat
authors.forename: Paiboon
authors.initials: P
authors.lastname: Techalertpaisarn
authors.forename: Antheunis
authors.initials: A
authors.lastname: Versluis
mesh_terms: D019245:Compressive Strength; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008437:Maxilla / Q000033:anatomy & histology; D010513:Periodontal Ligament / Q000033:anatomy & histology*; D013718:Tensile Strength