title: Structural equation modeling for alteration of occlusal plane inclination.
abstract: OBJECTIVE
  Occlusal plane inclination is important to maintain a normal opening closing/biting function. However, there can be several causes that lead to alterations of the occlusal plane. The purpose of this study was to observe variations of occlusal plane inclination in adult patients, and to uncover the factors affecting changes in occlusal plane inclination with aging.
  
  
  METHODS
  Subjects were 143 patients. A cephalometric image was taken of these patients. In this study, our inquiry points were age, 3 variables on intra-oral findings, and 7 variables on cephalometric analysis. To evaluate the possible causes that affect occlusal plane inclination, factor analysis was carried out, and each component was treated as factors, which were then statistically applied to a structural equation model. Statistical analysis was carried out through the SPSS 20.0 (SPSS Inc., Chicago, USA).
  
  
  RESULTS
  In all patients, Camper-occlusal plane angle (COA) ranged from -25.7 to -4.9° (Mean±SD: -6.4±5.36). In the 60 patients who had no missing teeth, COA ranged from -11.6 to -4.9° (Mean±SD: -3.3±3.31). From the results of the structural analysis, it was suggested that the occlusal plane changes to counter-clockwise (on the right lateral cephalograms) with aging.
  
  
  CONCLUSIONS
  In this study, variations of occlusal plane inclination in adult patients were observed, and the factors affecting changes in occlusal plane inclination with aging were investigated via factor analysis. From our results, it was suggested that the mandibular morphology change and loss of teeth with aging influence occlusal plane inclination.
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan. Electronic address: shigeta-y@tsurumi-u.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shigeta
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Ando
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Rio
authors.initials: R
authors.lastname: Hirabayashi
authors.affiliation: Department of Fixed Prosthodontics, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ikawa
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology*; D002508:Cephalometry; D003766:Dental Occlusion; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000473:pathology; D008875:Middle Aged; D003765:Models, Dental; D014070:Tooth / Q000473:pathology; D055815:Young Adult
keywords: Aging; Camper-occlusal plane angle; Cephalometric image; Missing teeth; Occlusal plane