title: Rehardening of caries-like lesions in root surfaces by saliva substitutes.
abstract: OBJECTIVE
  This study sought to evaluate whether root dentine caries-like lesions could be remineralised by saliva substitutes.
  
  
  METHODS
  Root dentine slabs (3 x 3 x 2 mm) were cut from bovine incisors, ground flat, polished and pre-tested for Knoop microhardness (KHN) at five locations spaced 500 microm apart and 500 microm from the left edge of each sectioned piece. After 60 out of the 100 slabs had been selected based upon their KHN values, specimens were coated with wax except for their outer surface. Specimens were then cycled through a highly cariogenic challenge model to induce caries-like lesions, whose formation was confirmed by KHN measurements located 500 microm from the right edge of the specimen. According to a randomised complete block design, the experimental units (n = 15) were exposed to 1.5 ml of saliva substitutes, based on either mucin (MC) or carboxymethylcellulose (CM), to natural human saliva (HS) or to 100% relative humidity (RH) over 20 days. Remineralisation was verified by KHN measurements located 1000 microm apart from the right edge of the specimen.
  
  
  RESULTS
  Analysis of variance indicated a significant (p < 0.0001) difference among the KHN values attained by the carious root dentine after exposure to the remineralising agents. Tukey's test ascertained that remineralisation was greatest with MC, intermediate with CM and least with HS, but rehardening did not reach the pre-caries lesion formation values.
  
  
  CONCLUSIONS
  Saliva substitutes may provide partial remineralisation to preformed caries-like lesions in root dentine.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil. cturssi@yahoo.com
authors.forename: Cecilia P
authors.initials: CP
authors.lastname: Turssi
authors.forename: Renata Q V
authors.initials: RQ
authors.lastname: Lima
authors.forename: Juliana J
authors.initials: JJ
authors.lastname: Faraoni-Romano
authors.forename: Mônica C
authors.initials: MC
authors.lastname: Serra
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000818:Animals; D002266:Carboxymethylcellulose Sodium / Q000627:therapeutic use; D002417:Cattle; D003804:Dentin; D003808:Dentin Solubility; D005260:Female; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009077:Mucins / Q000627:therapeutic use; D017213:Root Caries / Q000188:drug therapy*; D012463:Saliva; D012464:Saliva, Artificial / Q000737:chemistry / Q000627:therapeutic use*; D018709:Statistics, Nonparametric; D014089:Tooth Remineralization / Q000379:methods*
chemical_list: D009077:Mucins; D012464:Saliva, Artificial; D002266:Carboxymethylcellulose Sodium