title: Biomechanical effects of cervical lesions and restoration on periodontally compromised teeth.
abstract: OBJECTIVE
  The purpose of this study was to photoelastically evaluate the effects of cervical root lesions and their restoration on stress distribution in periodontally compromised teeth.
  
  
  METHODS
  Three-dimensional composite photoelastic models of a maxillary first premolar with buccal cervical root lesions were fabricated. Two different lesion configurations, wedge- and shallow saucer-shaped, at 20% alveolar bone height reduction were tested. A 35% reduction model was given a wedge-shaped lesion. The lesions were restored with microfine resin composite. Vertical loads of 7.5 lbs were applied to the unrestored and restored models at the tip of the buccal cusp and the tip of the lingual cusp. The resulting stresses within the tooth models were monitored and recorded photographically in the field of a circular polariscope arrangement.
  
  
  RESULTS
  For buccal cusp loading of the unrestored models, stress concentrated at the apex of the lesion regardless of the lesion shape or periodontal support conditions. The highest stress concentration was observed around the apex of the wedge-shaped lesion on the 35% reduction model. Restoring the lesions changed stress distribution. Restoration of the lesions resulted in a marked stress reduction at the lesion apex. Stress along the gingival restoration-model interface was characteristic for the restored situation. The interfacial stress followed the contour of the restoration most closely for the wedge-shaped lesion on the 20% support reduction model.
  
  
  CONCLUSIONS
  The shape and dimension of the lesion as well as periodontal support status has considerable influence on stress distribution, especially around the lesion, restored or not restored.
authors.affiliation: Division of Comprehensive Conservative Dentistry, Dental Hospital, Hokkaido University, Sapporo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kuroe
authors.forename: A A
authors.initials: AA
authors.lastname: Caputo
authors.forename: N
authors.initials: N
authors.lastname: Ohata
authors.forename: H
authors.initials: H
authors.lastname: Itoh
mesh_terms: D016301:Alveolar Bone Loss / Q000145:classification / Q000503:physiopathology*; D001641:Bicuspid; D001696:Biomechanical Phenomena; D003188:Composite Resins / Q000737:chemistry; D003793:Dental Restoration, Permanent; D004548:Elasticity; D006801:Humans; D008027:Light; D008953:Models, Anatomic; D010781:Photography; D013314:Stress, Mechanical; D019237:Tooth Cervix / Q000503:physiopathology*; D014076:Tooth Diseases / Q000473:pathology / Q000503:physiopathology*; D014092:Tooth Root / Q000473:pathology / Q000503:physiopathology; D020390:Tooth Socket / Q000473:pathology / Q000503:physiopathology; D016474:Weight-Bearing
chemical_list: D003188:Composite Resins; C074741:Silux Plus