title: Effects of in-office tooth whiteners on hardness of tooth-colored restoratives.
abstract: This study investigated the effects of in-office tooth whiteners on the hardness of hybrid (Spectrum TPH), polyacid-modified (Dyract AP), PRG (Reactmer) composites and a resin-modified glass ionomer cement (Fuji II LC). Twenty-seven specimens of each material were fabricated, randomly divided into three groups of nine and treated as follows--Group 1: stored in distilled water at 37 degrees C for three weeks (control); Group 2: treated with carbamide peroxide (Opalescence Quick) for 30 minutes/week for three weeks; Group 3: treated with 35% hydrogen peroxide power bleach (Opalescence Xtra) for 30 minutes/week for three weeks. For Groups 2 and 3, specimens were stored in distilled water at 37 degrees C during the hiatus periods. The treated specimens were subsequently subjected to microhardness testing (load = 500gf; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's test (p<0.05). For all treatment groups, Spectrum was significantly harder than the other materials and Reactmer was significantly harder than Dyract and Fuji II LC. The effects of in-office tooth whiteners on microhardness were material-dependent. No significant difference in hardness was observed between treatment groups for Dyract and Reactmer. For Spectrum and Fuji II LC, specimens treated with Opalescence Quick were significantly harder than those treated with Opalescence Xtra. No significant difference in hardness was observed between the control and bleached groups for all materials. The hardness of resin-modified glass-ionomer cements, hybrid, polyacid-modified and PRG composites is therefore not significantly affected by the use of 35% carbamide peroxide and 35% hydrogen peroxide in-office tooth whiteners.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
authors.forename: A U J
authors.initials: AU
authors.lastname: Yap
authors.forename: P
authors.initials: P
authors.lastname: Wattanapayungkul
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D004338:Drug Combinations; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D020770:Compomers; D003188:Composite Resins; D003764:Dental Materials; D004338:Drug Combinations; C088486:Dyract; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D008689:Methacrylates; D016877:Oxidants; D010545:Peroxides; D019279:Resin Cements; D012117:Resins, Synthetic; D017640:Silicates; C113300:TPH hybrid; C447779:reactmer bond; D014867:Water; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide