title: Lower incisor dentoalveolar compensation and symphysis dimensions among Class I and III malocclusion patients with different facial vertical skeletal patterns.
abstract: OBJECTIVE
  To compare lower incisor dentoalveolar compensation and mandible symphysis morphology among Class I and Class III malocclusion patients with different facial vertical skeletal patterns.
  
  
  METHODS
  Lower incisor extrusion and inclination, as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 107 lateral cephalometric x-rays of adult patients without prior orthodontic treatment. In addition, malocclusion type (Class I or III) and facial vertical skeletal pattern were considered. Through a principal component analysis (PCA) related variables were reduced. Simple regression equation and multivariate analyses of variance were also used.
  
  
  RESULTS
  Incisor mandibular plane angle (P < .001) and extrusion (P  =  .03) values showed significant differences between the sagittal malocclusion groups. Variations in the mandibular plane have a negative correlation with LA (Class I P  =  .03 and Class III P  =  .01) and a positive correlation with LH (Class I P  =  .01 and Class III P  =  .02) in both groups. Within the Class III group, there was a negative correlation between the mandibular plane and LP (P  =  .02). PCA showed that the tendency toward a long face causes the symphysis to elongate and narrow. In Class III, alveolar narrowing is also found in normal faces.
  
  
  CONCLUSIONS
  Vertical facial pattern is a significant factor in mandibular symphysis alveolar morphology and lower incisor positioning, both for Class I and Class III patients. Short-faced Class III patients have a widened alveolar bone. However, for long-faced and normal-faced Class III, natural compensation elongates the symphysis and influences lower incisor position.
authors.affiliation: a  Clinical Instructor, Department of Orthodontics, School of Dentistry, Universitat Internacional de Catalunya, Sant Cugat del Vallés, Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Molina-Berlanga
authors.forename: Jaume
authors.initials: J
authors.lastname: Llopis-Perez
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Mir
authors.forename: Andreu
authors.initials: A
authors.lastname: Puigdollers
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002508:Cephalometry / Q000379:methods; D005145:Face / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008297:Male; D008311:Malocclusion, Angle Class I / Q000000981:diagnostic imaging / Q000473:pathology*; D008313:Malocclusion, Angle Class III / Q000000981:diagnostic imaging / Q000473:pathology*; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D025341:Principal Component Analysis; D011859:Radiography; D014716:Vertical Dimension