title: Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents.
abstract: OBJECTIVE
  This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc.) and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents.
  
  
  METHODS
  Thirty composite resin (Filtek Z250; 3M/ESPE) samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent), group II (exposed to a compounded bleaching agent) and group III (control - Milli-Q water). After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%.
  
  
  RESULTS
  After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II.
  
  
  CONCLUSIONS
  The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching).
authors.affiliation: Post Graduate Program in Dental Sciences, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Renata Plá Rizzolo
authors.initials: RP
authors.lastname: Bueno
authors.forename: Paloma Salomone
authors.initials: PS
authors.lastname: Viaro
authors.forename: Paulo Cícero
authors.initials: PC
authors.lastname: Nascimento
authors.forename: Roselaine Terezinha
authors.initials: RT
authors.lastname: Pozzobon
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry*; D006801:Humans; D007477:Ions / Q000737:chemistry; D008422:Materials Testing; D010545:Peroxides / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D003188:Composite Resins; D007477:Ions; D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea