title: In vitro evaluation of the effect of different polishing techniques on the surface roughness of composite resins submitted to at-home and in-office bleaching procedures.
abstract: OBJECTIVE
  Bleaching agents may affect the properties of dental materials. The aim of this study was to evaluate the effect of different polishing techniques on the surface roughness of composite resins submitted to the at-home and in-office bleaching treatment.
  
  
  METHODS
  Disc-shaped specimens were carried out of nanofilled and microhybrid composites (n = 10). Finishing step was performed after light curing (L1) and polishing after 24 h with two systems (L2). Then, specimens were submitted to the home or in-office bleaching procedures, and roughness was re-evaluated (L3). The surface roughness (Ra) readings were measured at L1, L2, and L3 times using a profilometer. Data were statistically analyzed by multiple-way analysis of variance and Tukey test (α = 0.05).
  
  
  RESULTS
  The polishing procedures decreased Ra for both composites compared to baseline values (L1). The roughness of specimens polished with jiffy did not present significant difference after polishing step (L2) and bleaching treatment (L3). However, the groups polished with Sof-Lex discs had increase on the Ra values after bleaching.
  
  
  CONCLUSIONS
  The polishing is an important procedure to reduce the roughness of dental restorations and composite surface polished with jiffy system improved the degradation resistance to the bleaching agents compared to Sof-Lex discs.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Michele
authors.initials: M
authors.lastname: de Oliveira Lima
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Anderson
authors.initials: A
authors.lastname: Catelan
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Natália Maria Pinto
authors.initials: NM
authors.lastname: Hernandes
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Maria Cecília Caldas
authors.initials: MC
authors.lastname: Giorgi
authors.affiliation: Department of Social Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Gláucia Maria Bovi
authors.initials: GM
authors.lastname: Ambrosano
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Débora Alves Nunes Leite
authors.initials: DA
authors.lastname: Lima
keywords: Composite resin; dental bleaching; surface roughness