title: Microhardness and color monitoring of nanofilled resin composite after bleaching and staining.
abstract: OBJECTIVE
  The present study aimed to investigate the effect of staining solutions on microhardness and shade changes of a nanofilled resin composite, which had been previously in contact with bleaching agents.
  
  
  METHODS
  A total of 135 disk-shaped specimens (10 mm × 2 mm) were fabricated with a nanofilled resin (Filtek Supreme) and photocured with a Light Emission Diode (LED) unit and then allocated into three groups to be bleached with 10% or 16% carbamide peroxide (CP) bleaching agents or a 35% hydrogen peroxide (HP) product. Following bleaching, specimens within each group were subdivided into three groups to be immersed in coffee, red wine or distilled water. Microhardness and color were monitored at baseline, after bleaching and after staining.
  
  
  RESULTS
  Analysis of variance for split-plot design showed lower microhardness values when the composite had been in contact with HP (P < 0.0001). The specimens immersed in red wine and coffee provided lower microhardness values than those immersed in distilled water, regardless of the bleaching agent to which the composites were previously exposed. Kruskal Wallis and Dunn tests demonstrated that the composite was lighter after bleaching with a 35% HP agent (P < 0.0500).
  
  
  CONCLUSIONS
  The composite was darker as a result of being immersed either in red wine or coffee, regardless of the bleaching agent.
authors: Department of Restorative Dentistry, Regional University of Blumenau, Blumenau, SC, Brazil.
authors: Isabel Cristina G Bandeira
authors: ICGB
authors: de Andrade
authors: Department of Restorative Dentistry, São Leopoldo Mandic Institute and Dental Research Center, Campinas, SP, Brazil.
authors: Roberta Tarkany
authors: RT
authors: Basting
authors: Department of Restorative Dentistry School of Dentistry, Guarulhos University, São Paulo, SP, Brazil.
authors: José Augusto
authors: JA
authors: Rodrigues
authors: Department of Restorative Dentistry, São Leopoldo Mandic Institute and Dental Research Center, Campinas, SP, Brazil.
authors: Flávia Lucisano Botelho
authors: FLB
authors: do Amaral
authors: Department of Restorative Dentistry, São Leopoldo Mandic Institute and Dental Research Center, Campinas, SP, Brazil.
authors: Cecilia Pedroso
authors: CP
authors: Turssi
authors: Department of Restorative Dentistry, São Leopoldo Mandic Institute and Dental Research Center, Campinas, SP, Brazil.
authors: Fabiana Mantovani Gomes
authors: FMG
authors: França
keywords: Bleaching agents; color change; laboratory research; microhardness; nanofilled composites; staining solutions