title: Symmetry of non-carious cervical lesions in canines and premolars.
abstract: OBJECTIVE
  Clinically non-carious cervical lesions (NCCLs) are frequently seen. The aim of this study was to investigate the relationship between the shape and symmetry of NCCLs, wear of cuSPS and triangular ridge, and the curvature of the tooth root.
  
  
  METHODS
  One hundred and twenty-nine extracted human upper canine teeth and 274 extracted human upper premolar teeth with NCCLs were used in this study. The specimens were studied using photographs and three-dimensional scanning.
  
  
  RESULTS
  Asymmetric NCCL was observed in 69.0% of the canines and 44.5% of the premolars. Wear of cusp and lingual ridges was observed in 82.9% and 93.0% of the canines, respectively. Wear of the buccal cusp and buccal triangular ridge was observed in 85.4% and 89.8% of the premolars, respectively. On the other hand, the wear of lingual cusp and lingual triangular ridge was observed in 89.1% and 93.8% of the premolars, respectively. The curvature of the root was observed in 48.1% of the canines and 43.4% of the premolars.
  
  
  CONCLUSIONS
  There was no relationship between the symmetry of NCCLs, and the wear of cuSPS and triangular ridges for either canines or premolars. Although there was a relationship (p < 0.05) between the symmetry of NCCL and the curvature of the root in the canines, no relationship was observed between the symmetry of NCCL and the curvature of the root in the premolars.
authors.affiliation: General Dentistry, University Hospital, The Nippon Dental University, School of Dentistry at Tokyo, 2-3-16 Fujimi, Chiyoda-ku, Tokyo 102-8158, Japan. thinkpad720c@yahoo.co.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Maseki
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D001641:Bicuspid / Q000033:anatomy & histology / Q000473:pathology; D016009:Chi-Square Distribution; D003481:Cuspid / Q000033:anatomy & histology / Q000473:pathology; D006801:Humans; D015995:Prevalence; D014072:Tooth Abrasion / Q000473:pathology*; D019237:Tooth Cervix / Q000033:anatomy & histology / Q000473:pathology*; D014092:Tooth Root / Q000473:pathology*