title: Effect of 10% carbamide peroxide dental bleaching on microhardness of filled and unfilled sealant materials.
abstract: OBJECTIVE
  The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials.
  
  
  METHODS
  Fluroshield, Vitroseal Alfa, and one unfilled (Clinpro) sealants were placed in Teflon matrices (4 mm in diameter by 2 mm in height) and polymerized for 40 seconds. A total of 20 specimens were prepared for each material, in which half were assigned as the control group (stored in artificial saliva and no bleaching treatment). For the remaining half, Clarigel Gold bleaching agent (10% carbamide peroxide) was placed over the specimen surface for 4 hours/day during 4 weeks. When specimens were not under bleaching treatment, they were kept in artificial saliva. Afterwards, specimens were subjected to Knoop microhardness testing using a 25-g load for 5 seconds. Five measurements were made on the sealants' surfaces and then calculated in Knoop hardness values. The data were statistically analyzed by two-way analysis of variance and Tukey's tests with a 5% confidence level.
  
  
  RESULTS
  The results of this in vitro study showed that the application of a carbamide peroxide-based bleaching material significantly affected the microhardness values of filled sealant materials. The bleaching agent did not affect the microhardness of the unfilled sealant. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that the bleaching agents altered the surface hardness of filled sealant restorative materials. This could possibly lead to increased wear and surface roughness.
authors.affiliation: Department of Restorative Dentistry, Piracicaba School of Dentistry-Unicamp, Piracicaba, Brazil.
authors.forename: Rodrigo Sversut
authors.initials: RS
authors.lastname: de Alexandre
authors.forename: Renato Herman
authors.initials: RH
authors.lastname: Sundfeld
authors.forename: André Luiz Fraga
authors.initials: AL
authors.lastname: Briso
authors.forename: Ana Karina B
authors.initials: AK
authors.lastname: Bedran-Russo
authors.forename: Thiago Assunção
authors.initials: TA
authors.lastname: Valentino
authors.forename: Maria Lúcia Marçal Mazza
authors.initials: ML
authors.lastname: Sundefeld
mesh_terms: D000077463:Carbamide Peroxide; D004338:Drug Combinations; D006244:Hardness / Q000187:drug effects; D016877:Oxidants / Q000494:pharmacology*; D010545:Peroxides / Q000494:pharmacology*; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D014073:Tooth Bleaching / Q000009:adverse effects*; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D010895:Pit and Fissure Sealants; D000077463:Carbamide Peroxide; D014508:Urea