title: Effects of phosphoric acid on bovine enamel bleached with carbamide peroxide.
abstract: The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 x 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, specimens were stored in artificial saliva for 0, 24, 72 h, or 7 d and then immersed in 37% phosphoric solution. At 15, 30, 60, 90, and 120 s, 5-ml aliquots were extracted. A control group of specimens was not bleached. Ca(2+) concentrations were measured by atomic absorption spectrophotometry. A larger amount of Ca(2+) was extracted from enamel by phosphoric acid after the application of 30% carbamide peroxide. Twenty-four hours after bleaching, significantly more Ca(2+) was extracted from bleached than from control specimens at all time-points, and this greater susceptibility to the action of the acid persisted for at least 1 wk after bleaching.
authors.affiliation: Department of Restorative Dentistry, University of Paraiba, Campina Grande, Brasil.
authors.forename: Carmen L S G
authors.initials: CL
authors.lastname: de Medeiros
authors.forename: Santiago
authors.initials: S
authors.lastname: González-López
authors.forename: Maria V
authors.initials: MV
authors.lastname: Bolaños-Carmona
authors.forename: Purificación
authors.initials: P
authors.lastname: Sanchez-Sanchez
authors.forename: Jorge
authors.initials: J
authors.lastname: Bolaños-Carmona
mesh_terms: D000134:Acid Etching, Dental / Q000009:adverse effects; D000818:Animals; D002118:Calcium / Q000032:analysis; D000077463:Carbamide Peroxide; D002417:Cattle; D003743:Dental Enamel / Q000187:drug effects*; D003764:Dental Materials / Q000009:adverse effects*; D004338:Drug Combinations; D016877:Oxidants / Q000009:adverse effects*; D010545:Peroxides / Q000009:adverse effects*; D010756:Phosphoric Acids / Q000009:adverse effects*; D013997:Time Factors; D014073:Tooth Bleaching / Q000009:adverse effects*; D017001:Tooth Demineralization / Q000139:chemically induced; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D003764:Dental Materials; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D010756:Phosphoric Acids; D000077463:Carbamide Peroxide; D014508:Urea; C030242:phosphoric acid; D002118:Calcium