title: Effect of bleaching agents on surface free energy parameters of resin composite coated with saliva biofilm.
abstract: OBJECTIVE
  To assess the effect of 10% carbamide peroxide and 10% hydrogen peroxide bleaching preparations on the surface free energy of resin composite with and without saliva biofilm coating.
  
  
  METHODS
  72 light-cured resin composite samples were used. The samples were either coated with fresh human saliva or left uncoated. Each sample was placed in a plastic assay tube containing 2 ml of either 10% carbamide peroxide (CP), 10% hydrogen peroxide (HP), or phosphate buffer solution. The tubes containing the composite samples were then placed in a dry incubator at 37 degrees C for 1- and 3-day time intervals. After each time interval the samples were rinsed with distilled water and subjected to wetting measurements using a captive bubble technique. Measurements were taken in triplicate and determination of contact angles done by using film negatives on an enlarger. The differences between pre-treatment and post-treatment measurements and between samples coated with saliva and non-coated samples were analyzed statistically for each time period and treatment group.
  
  
  RESULTS
  10% CP reduced octane contact angle of all exposed composite groups after 1 day of treatment regardless of saliva coating. Differences between the pre-bleached and post-bleached groups were statistically significant only for octane contact angles measured in saliva-coated samples (P < 0.05). 10% CP reduced both the octane and air contact angles of all exposed composite surfaces after 3 days of treatment. The reduction was statistically significant only for octane contact angles measured in the saliva-coated samples (P < 0.05). Additionally, 10% CP significantly reduced the surface free energy of saliva-coated samples after 1-day treatment as compared to non-coated samples. 10% HP reduced octane contact angle of all exposed composite groups after 1 day of treatment regardless of saliva coating. The differences between the pre-bleached and post-bleached groups were statistically significant only for octane contact angles measured in the saliva-coated samples (P < 0.05). 10% HP reduced both the octane and air contact angles of all exposed resin composite surface samples after 3 days of treatment regardless of saliva coating. However, the differences between the groups were not statistically significant.
authors.affiliation: Department of Endodontics, Hacettepe University, Ankara, Turkey.
authors.forename: Hatice Dogan
authors.initials: HD
authors.lastname: Buzoglu
authors.forename: Menemse
authors.initials: M
authors.lastname: Gümüsderelioğlu
authors.forename: Ilan
authors.initials: I
authors.lastname: Rotstein
mesh_terms: D000388:Air; D000465:Algorithms; D002021:Buffers; D000077463:Carbamide Peroxide; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D008422:Materials Testing; D009795:Octanes / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D012463:Saliva / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry; D017155:Wettability
chemical_list: D002021:Buffers; C084111:Charisma composite resin; D020099:Coated Materials, Biocompatible; D003188:Composite Resins; D003764:Dental Materials; D004338:Drug Combinations; D009795:Octanes; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C026728:octane