title: Effects of acids used in the microabrasion technique: Microhardness and confocal microscopy analysis.
abstract: BACKGROUND
  This study evaluated the effects of the acids used in the microabrasion on enamel.
  
  
  METHODS
  Seventy enamel/dentine blocks (25 mm2) of bovine incisors were divided into 7 groups (n=10). Experimental groups were treated by active/passive application of 35% H3PO4 (E1/E2) or 6.6% HCl (E3/E4). Control groups were treated by microabrasion with H3PO4+pumice (C5), HCl+silica (C6), or no treatment (C7). The superficial (SMH) and cross-sectional (CSMH; depths of 10, 25, 50, and 75 µm) microhardness of enamel were analyzed. Morphology was evaluated by confocal laser-scanning microscopy (CLSM). Data were analyzed by analysis of variance (Proc Mixed), Tukey, and Dunnet tests (α=5%).
  
  
  RESULTS
  Active application (E1 and E3) resulted in higher microhardness than passive application (E2 and E4), with no difference between acids. For most groups, the CSMH decreased as the depth increased. All experimental groups and negative controls (C5 and C6) showed significantly reduced CSMH values compared to the control. A significantly higher mean CSMH result was obtained with the active application of H3PO4 (E1) compared to HCl (E3). Passive application did not result in CSMH differences between acids. CLSM revealed the conditioning pattern for each group.
  
  
  CONCLUSIONS
  Although the acids displayed an erosive action, use of microabrasive mixture led to less damage to the enamel layers.
  
  
  BACKGROUND
  Enamel microabrasion, enamel microhardness, confocal laser scanning microscopy.
authors.affiliation: PhD applicant in Restorative Dentistry, Piracicaba Dental School, University of Campinas - FOP/Unicamp.
authors.forename: Núbia-Inocencya-Pavesi
authors.initials: NI
authors.lastname: Pini
authors.affiliation: Professor, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas - FOP/Unicamp.
authors.forename: Débora-Alves-Nunes-Leite
authors.initials: DA
authors.lastname: Lima
authors.affiliation: Professor, Department of Social Dentistry/Statistics, Piracicaba Dental School, State University of Campinas, Piracicaba-SP/Brazil.
authors.forename: Gláucia-Maria-Bovi
authors.initials: GM
authors.lastname: Ambrosano
authors.affiliation: Professor, Department of Prosthesis, Piracicaba Dental School, State University of Campinas, Piracicaba-SP/Brazil.
authors.forename: Wander-José
authors.initials: WJ
authors.lastname: da Silva
authors.affiliation: Professor, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas - FOP/Unicamp.
authors.forename: Flávio-Henrique-Baggio
authors.initials: FH
authors.lastname: Aguiar
authors.affiliation: Professor, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas - FOP/Unicamp.
authors.forename: José-Roberto
authors.initials: JR
authors.lastname: Lovadino