title: Influence of Restoration Type on the Cytotoxicity of a 35% Hydrogen Peroxide Bleaching Gel.
abstract: OBJECTIVE
  The tooth/restoration interface may act as a pathway for hydrogen peroxide (H2O2) diffusion into the pulp chamber. Therefore, the influence of resin-modified glass ionomer cement (RMGIC) and resin composite simulated restorations on the cytotoxicity of an in-office bleaching gel was assessed in vitro.
  
  
  METHODS
  Cavities in enamel/dentin discs restored with RMGIC Vitremer (3M ESPE) or Single Bond/Filtek Z350 (3M ESPE) resin composite (RC) were subjected or not subjected to hydrolytic degradation (HD). A 35%-H2O2 bleaching gel was applied to simulated restored and nonrestored enamel surfaces, and culture medium in contact with the dentin substrate (extract) was collected and applied to MDPC-23 cells. Nonrestored discs subjected or not subjected to bleaching were used as positive and negative controls, respectively. Cell viability, oxidative stress, interleukin (IL)-1β expression, alkaline phosphatase (ALP) activity, and mineralized nodule deposition were evaluated. The H2O2 in the extracts was quantified. Data were subjected to statistical analysis.
  
  
  RESULTS
  Higher oxidative stress associated with reduced cell viability, ALP activity, and mineralized nodule deposition was observed for all bleached groups compared with the negative control group. The RMGIC/HD group, which presented the highest H2O2 diffusion, had the lowest values of cell viability, ALP activity, and mineralized nodule deposition, as well as significantly increased IL-1β expression.
  
  
  CONCLUSIONS
  Dental cavities restored with the RMGIC subjected to hydrolytic degradation allowed for more intense diffusion of H2O2 into the pulp chamber, intensifying the toxicity of a 35%-H2O2 bleaching gel to pulp cells.
authors.forename: D G
authors.initials: DG
authors.lastname: Soares
authors.forename: N
authors.initials: N
authors.lastname: Marcomini
authors.forename: F G
authors.initials: FG
authors.lastname: Basso
authors.forename: T N
authors.initials: TN
authors.lastname: Pansani
authors.forename: J
authors.initials: J
authors.lastname: Hebling
authors.forename: C A
authors.initials: CA
authors.lastname: de Souza Costa
mesh_terms: D003188:Composite Resins; D003743:Dental Enamel; D003782:Dental Pulp; D003793:Dental Restoration, Permanent; D003804:Dentin; D005899:Glass Ionomer Cements; D006861:Hydrogen Peroxide; D014073:Tooth Bleaching
chemical_list: D003188:Composite Resins; D005899:Glass Ionomer Cements; D006861:Hydrogen Peroxide