title: Effect of hydrogen peroxide on microhardness and color change of resin nanocomposites.
abstract: OBJECTIVE
  To examine the effect of hydrogen peroxide on the microhardness and color change of resin composites containing nanofillers.
  
  
  METHODS
  Three resin nanocomposites with three different shades and two different tooth whitening agents were used. The specimens were given a 3-week treatment with one of three protocols: (1) 7 hours/day treatment of carbamide peroxide (CP) + 17 hours/day immersion in distilled water (DW); (2) 1 hour/week treatment of hydrogen peroxide (HP) + immersion in DW for the rest of the week; and (3) immersion in DW for 24 hours/day. The microhardness and color changes were measured after treatment.
  
  
  RESULTS
  After treatment with the whitening agents, there was an 8.1-10.7% decrease in the original microhardness. These values were similar to those obtained from the samples treated with distilled water. In the same resin product, the decrease was similar regardless of the test agents used. In most cases, the color change was only slight (deltaE*=0.5-1.4). Hydrogen peroxide enhanced the color change but the absolute color change values were similar in the same product and shade, regardless of the test agent used.
authors.affiliation: Department of Dental Materials, School of Dentistry, Pusan National University, Yangsan 626-870, Korea. y0k0916@pusan.ac.kr
authors.forename: Yong Hoon
authors.initials: YH
authors.lastname: Kwon
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Shin
authors.forename: Dong-In
authors.initials: DI
authors.lastname: Yun
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Heo
authors.forename: Hyo-Joung
authors.initials: HJ
authors.lastname: Seol
authors.forename: Hyung-Il
authors.initials: HI
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D004338:Drug Combinations; D006244:Hardness; D006861:Hydrogen Peroxide; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry; D016877:Oxidants; D010545:Peroxides; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives
chemical_list: C520091:CeramX; D003188:Composite Resins; D004338:Drug Combinations; C509998:Grandio; D016877:Oxidants; D010545:Peroxides; C533204:filtek Z350; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide