title: Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentine.
abstract: The purpose of this study was to compare the effect of traditional and alternative bleaching agents on microhardness of human dentine when used intracoronally. Thirty-six premolars were divided into six groups and bleaching agents were sealed into the pulp chambers as follows: group 1--distilled water (control), group 2--30% hydrogen peroxide solution, group 3--sodium perborate mixed with distilled water, group 4--sodium perborate mixed with 30% hydrogen peroxide solution, group 5--35% carbamide peroxide gel, group 6--35% hydrogen peroxide gel. Access cavities were sealed and the teeth were stored in distilled water at 37 degrees C. After 7 days, each tooth was sectioned at the cemento-enamel junction level and microhardness testing was carried out on dentine. The results showed that treatment with 35% hydrogen peroxide gel, 30% hydrogen peroxide solution and 35% carbamide peroxide gel reduced the microhardness of outer dentine to a small extent while treatment with sodium perborate mixed with water and sodium perborate mixed with 30% hydrogen peroxide solution did not significantly alter the microhardness of dentine.
authors.affiliation: Faculty of Dentistry, Department of Restorative Dentistry, National University of Singapore, Singapore. rsdchk@nus.edu.sg
authors.forename: H K
authors.initials: HK
authors.lastname: Chng
authors.forename: A U J
authors.initials: AU
authors.lastname: Yap
authors.forename: P
authors.initials: P
authors.lastname: Wattanapayungkul
authors.forename: C P C
authors.initials: CP
authors.lastname: Sim
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001881:Borates / Q000494:pharmacology*; D000077463:Carbamide Peroxide; D003804:Dentin / Q000187:drug effects / Q000502:physiology*; D004338:Drug Combinations; D005782:Gels; D006244:Hardness; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D010545:Peroxides / Q000494:pharmacology*; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D001881:Borates; D004338:Drug Combinations; D005782:Gels; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C027707:sodium perborate