title: Tooth enamel properties and morphology after microabrasion: an in situ study.
abstract: OBJECTIVE
  This study evaluated the effect of saliva on enamel after microabrasion with different microabrasive compounds under in situ conditions.
  
  
  METHODS
  Enamel/dentin blocks (16 mm2) from bovine incisors were divided into nine groups (n = 19): one control group (no treatment), four groups treated with microabrasion using 35% phosphoric acid (H3PO4) + pumice, and the last four groups treated with microabrasion using 6.6% hydrochloric acid (HCl) + silica. The treated groups were subdivided according to the in situ regimen: without salivary exposure, 1 h, 24 h, or 7 days of saliva exposure. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were tested. Scanning electron microscopy (SEM) was used to evaluate enamel morphology. Microhardness data were tested by analysis of variance, and Tukey's and Dunnett's tests (α = 0.05).
  
  
  RESULTS
  The SMH analysis revealed that all the microabrasion-treated groups presented significantly-reduced SMH values when compared to the control group (P < 0.05). Treatment with HCl + silica was more prone to the effect of saliva than H3PO4+ pumice, even for CSMH analysis, once the superficial layers reached the same microhardness of that of the control group (P > 0.05). These results were confirmed by SEM, which demonstrated the mineral recovery effect over time.
  
  
  CONCLUSIONS
  Saliva was effective in promoting the rehardening of enamel after microabrasion, mainly for the surfaces treated with HCl + silica.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Núbia Inocencya Pavesi
authors.initials: NIP
authors.lastname: Pini
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Débora Alves Nunes Leite
authors.initials: DANL
authors.lastname: Lima
authors.affiliation: Department of Restorative Dentistry, Araçatuba Dental School, Araçatuba, São Paulo, Brazil.
authors.forename: Renato Herman
authors.initials: RH
authors.lastname: Sundfeld
authors.affiliation: Department of Social Dentistry/Statistics, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Gláucia Maria Bovi
authors.initials: GMB
authors.lastname: Ambrosano
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Flavio Henrique Baggio
authors.initials: FHB
authors.lastname: Aguiar
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Lovadino
mesh_terms: D000328:Adult; D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D006244:Hardness; D064368:Healthy Volunteers; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology; D007180:Incisor; D008297:Male; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000494:pharmacology; D012463:Saliva / Q000502:physiology*; D017640:Silicates / Q000494:pharmacology; D012822:Silicon Dioxide; D013499:Surface Properties; D014072:Tooth Abrasion; D014074:Tooth Calcification; D055815:Young Adult
chemical_list: D010756:Phosphoric Acids; D017640:Silicates; D012822:Silicon Dioxide; C030242:phosphoric acid; C005144:pumice; D006851:Hydrochloric Acid
keywords: enamel; microabrasion; microhardness; remineralization; saliva