title: The effect of acid etchant type and dentin location on tubular density and dimension.
abstract: BACKGROUND
  Coronal and radicular dentin may react differently to the type of acid treatment used when bonding to these substrates.
  
  
  OBJECTIVE
  The purpose of this study was to characterize and compare dentin morphology, tubular density, and cross-sectional area in deep coronal (around an exposed pulp horn) and root canal dentin at the cervical third in the intact state and after acid etching with phosphoric acid or self-etching dentin primer.
  
  
  METHODS
  Extracted, human, caries-free premolars were fixed. Smear layer-free sections (control) were obtained and divided into 3 groups: left intact, etched with phosphoric acid, or etched with a self-etching primer from a dentin bonding system. Specimens were examined using scanning electron microscopy. Tubular density and cross-sectional area were determined from the images using software. Values were submitted to multifactorial ANOVA (alpha=.05).
  
  
  RESULTS
  Tubular density was not significantly affected by acid type or by dentin location. Acid type significantly (P<.001) affected tubular cross-sectional area: phosphoric acid > self-etching resin > intact dentin, irrespective of dentin location. All acid-treated specimens showed demineralization, and irregular surface morphology was not affected by either acid treatment.
  
  
  CONCLUSIONS
  Tubular density was not significantly different between deep coronal and root canal dentin nor affected by acid treatment type. Tubular cross-sectional area did not differ between deep coronal or root canal dentin, regardless of acid treatment. Both acid types significantly increased tubular cross-sectional area at both dentin locations, phosphoric acid to a greater degree than the self-etching primer. Root canal dentin did not display peritubular dentin.
authors.affiliation: Department of Restorative Dentistry, Area of Endodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil.
authors.forename: Ana Carolina Rocha Lima
authors.initials: AC
authors.lastname: Caiado
authors.forename: Mario Fernando
authors.initials: MF
authors.lastname: de Goes
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: de Souza-Filho
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Rueggeberg
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000704:Analysis of Variance; D019412:Anatomy, Cross-Sectional; D001641:Bicuspid; D003786:Dental Pulp Cavity; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000494:pharmacology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000494:pharmacology; D013499:Surface Properties; D019228:Tooth Crown
chemical_list: D017220:Dentin-Bonding Agents; D010756:Phosphoric Acids; C030242:phosphoric acid