title: The relationship between root concavities in first premolars and chronic periodontitis.
abstract: OBJECTIVE
  To evaluate the significance of first premolar root concavity on clinical indices of chronic periodontal disease and alveolar bone defects.
  
  
  METHODS
  Three-dimensional reconstruction by cone beam computed tomography was used to observe root surface anatomy and the type of alveolar bone defect seen in the mesial and distal sites of 272 first premolars from 99 patients who had presented with chronic periodontitis. Periodontal clinical indicators at each site were measured using a Florida Probe Corporation (Gainesville, FL, USA).
  
  
  RESULTS
  The incidence of mesial and distal root concavities of the maxillary first premolars was 100% and 39.3% respectively, and in the mandibular, the incidence was 42.5% and 31.3% respectively. The distributions of the different types of concavities in terms of both age and gender of the patients were not statistically significant. The mean probing depth and clinical attachment loss of the first premolars with root concavities were significantly higher than those without concavity (p < 0.05). Plaque accumulation was significantly different in the premolars with/without root concavities (p < 0.001). The type of alveolar bone defects with concavities was significantly different from those without concavities (p < 0.05). Ramp shape bone defects were dominant for teeth without concavities, while crater shape was seen for teeth with concavities.
  
  
  CONCLUSIONS
  Root concavities of the first premolars were associated with periodontal disease, and the type of interproximal alveolar bone defect. Root concavities may be important in contributing to local periodontal disease of the first premolars.
authors.affiliation: Department of Periodontics and Oral Biology, School of Stomatology, China Medical University, Shenyang, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Pan
authors.forename: C
authors.initials: C
authors.lastname: Pan
authors.forename: X
authors.initials: X
authors.lastname: Jin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000539:Alveolar Process / Q000000981:diagnostic imaging; D001641:Bicuspid / Q000000981:diagnostic imaging*; D055113:Chronic Periodontitis / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003774:Dental Plaque Index; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D008875:Middle Aged; D017622:Periodontal Attachment Loss / Q000145:classification; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000145:classification; D012737:Sex Factors; D014092:Tooth Root / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: alveolar bone defects; chronic periodontitis; cone beam computed tomography; first premolar; root concavity