title: Morphological characterization and permeability of attrited human dentine.
abstract: OBJECTIVE
  Dentine is a vital tissue that can be changed by physiological and pathological condition. The purpose of this study was to clarify the morphology and permeability of dentine that changed by wearing process.
  
  
  METHODS
  Twenty extracted human molars with enamel attrition and dentine was exposed and 20 intact human extracted third molars that had not reached occlusion were used. Ten teeth per each group were observed under light microscope (LM) and transmission electron microscope (TEM). Remaining 10 teeth per each group were subjected for evaluation of dentine permeability.
  
  
  RESULTS
  Under LM, the transparent dentine and reactionary dentine were found in the attrition group but were not found in the group unaffected by attrition. When the transparent dentine were examined under the TEM, it was found that dentinal tubules were partially or completely occluded by growth of peritubular dentine or by precipitation of needle-like or rhombohedral crystals in transparent dentine. In reactionary dentine, tubular dentine structures that were comparable to those in secondary physiologic dentine were observed whereas atubular dentine demonstrated occlusion of tubules by high mineral substances or by peritubular dentine under the TEM. Permeability of dentine from worn teeth was less than those from unoccluded teeth significantly.
  
  
  CONCLUSIONS
  Change in dentine by wear resulted in the formation of reactionary dentine and transparent dentine that illustrated various types and degrees of tubular occlusion. These decrease the dentine permeability.
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Mahidol University, Bangkok 10400, Thailand. dtpse@mahidol.ac.th
authors.forename: Pisol
authors.initials: P
authors.lastname: Senawongse
authors.forename: Masayuki
authors.initials: M
authors.lastname: Otsuki
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
authors.forename: Ivar A
authors.initials: IA
authors.lastname: Mjör
mesh_terms: D000134:Acid Etching, Dental; D016022:Case-Control Studies; D003460:Crystallization; D003743:Dental Enamel / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure*; D003806:Dentin Permeability; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008963:Molar; D014072:Tooth Abrasion / Q000473:pathology*