title: The effect of 2 different bleaching regimens on the surface roughness and hardness of tooth-colored restorative materials.
abstract: OBJECTIVE
  The purpose of this in vitro study was to evaluate the effects of 10% carbamide peroxide (Vivastyle/Vivadent) and 6.5% hydrogen peroxide strip bands (Crest Professional Whitestrips) on the surface roughness and hardness of the 3 different tooth-colored restoratives: an ormocer (Definite), a packable composite (Filtek P60), and a flowable composite (Filtek Flow).
  
  
  METHODS
  A total of 48 specimens (10 mm in diameter and 2 mm thick) of each material were fabricated against a mylar surface. After being polished with Sof-Lex discs, they were randomly divided into 3 groups of 16 and treated as follows: group I was stored in distilled water at 37 degrees C for 2 weeks (control), group II was treated with Vivastyle for 2 hours per day for 2 weeks, and group III was treated with Whitestrips for 30 minutes twice a day for 2 weeks. For groups II and III, the specimens were stored in distilled water at 37 degrees C during the hiatus period. At the end of the test period, the specimens were first subjected to surface roughness and then to microhardness tests. The data were analyzed by Kruskal-Wallis and Mann-Whitney U tests.
  
  
  RESULTS
  Both bleaching regimens increased the surface roughness of the materials (P <.05), but Whitestrips significantly increased the roughness of materials more than did Vivastyle (P <.05). Both bleaching regimens decreased significantly the hardness of tested materials except Filtek P60 (P <.05).
  
  
  CONCLUSIONS
  Bleaching agents may affect the surface of existing restorations; therefore, they should not be used indiscriminately when tooth-colored restorations are present.
authors.affiliation: Department of Restorative Dentistry, Hacettepe University, School of Dentistry, Ankara, Turkey. sgurgan@hacettepe.edu.tr
authors.forename: Sevil
authors.initials: S
authors.lastname: Gurgan
authors.forename: Filiz
authors.initials: F
authors.lastname: Yalcin
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry*; D004338:Drug Combinations; D006244:Hardness / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000009:adverse effects*; D016877:Oxidants / Q000009:adverse effects*; D010545:Peroxides / Q000009:adverse effects*; D011140:Polyurethanes / Q000737:chemistry*; D013499:Surface Properties / Q000187:drug effects; D014073:Tooth Bleaching / Q000009:adverse effects*; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D011140:Polyurethanes; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide