title: High resolution SEM evaluation of dentin etched with maleic and citric acid.
abstract: OBJECTIVE
  This study evaluated the ultra-morphological effects of maleic and citric acid on human dentin by means of a field emission in-lens scanning electron microscope (FEISEM). Both acids were tested on human dentin at pH 0.7 and 1.4 in aqueous solutions.
  
  
  METHODS
  Each of 12 dentin disks were divided into four groups and exposed to either maleic acid at pH 0.7, maleic acid at pH 1.4, citric acid at pH 0.7 and citric acid at pH 1.4. All samples were then fixed and dehydrated in a critical point drying apparatus. Observations were carried out by means of a FEISEM (JEOL 890) after coating with a carbon-platinum film.
  
  
  RESULTS
  Both acids removed smear layer and partially removed smear plugs. Details of fine structures measuring from 5 to 15 nm were shown on the intertubular demineralized dentin. Maleic acid at pH 0.7 showed the highest depth of demineralization of all the tested samples; citric acid, showed a higher depth of demineralization values when tested at pH 1.4 than at pH 0.7.
  
  
  CONCLUSIONS
  The FEISEM reveals ultra-structural aspects of the demineralization process of the dentin tissue of the both acids tested. Differences related to the pH of the acids were found. Images obtained at high magnification clarify the dentin collagen structure of both peritubular and intertubular dentin. Small periodic structures associated with collagen fibrils were also imagined.
authors.affiliation: Istituto di Anatomia Umana, Università di Bologna, Via Irnerio, 48, 1-40126, Bologna, Italy. lbreschi@biocfarm.unibo.it
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Pietro
authors.initials: P
authors.lastname: Gobbi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mazzotti
authors.forename: Mirella
authors.initials: M
authors.lastname: Falconi
authors.forename: Tom H
authors.initials: TH
authors.lastname: Ellis
authors.forename: Ivan
authors.initials: I
authors.lastname: Stangel
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D002244:Carbon; D019343:Citric Acid / Q000494:pharmacology*; D003094:Collagen / Q000648:ultrastructure; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008298:Maleates / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D008903:Minerals; D010984:Platinum; D016369:Smear Layer; D018709:Statistics, Nonparametric
chemical_list: D008298:Maleates; D008903:Minerals; D019343:Citric Acid; D010984:Platinum; D002244:Carbon; D003094:Collagen; C030272:maleic acid