title: Effect of fluoride-treated enamel on indirect cytotoxicity of a 16% carbamide peroxide bleaching gel to pulp cells.
abstract: The aim of this study was to evaluate the possibility of fluoride solutions applied to enamel to protect pulp cells against the trans-enamel and transdentinal cytotoxicity of a 16% carbamide peroxide (CP) bleaching gel. The CP gel was applied to enamel/dentin discs adapted to aicial pulp chambers (8 h/day) during 1, 7 or 14 days, followed by fluoride (0.05% or 0.2%) application for 1 min. The extracts (culture medium in contact with dentin) were applied to MDPC-23 cells for 1 h, and cell metabolism (MTT assay), alkaline phosphatase (ALP) activity and cell membrane damage (flow cytometry) were analyzed. Knoop microhardness of enamel was also evaluated. Data were analyzed statistically by ANOVA and Kruskal-Wallis tests (α=0.05). For the MTT assay and ALP activity, significant reductions between the control and the bleached groups were observed (p<0.05). No statistically significant difference occurred among bleached groups (p>0.05), regardless of fluoride application or treatment days. Flow cytometry analysis demonstrated 30% of cell membrane damage in all bleached groups. After 14 days of treatment, the fluoride-treated enamel presented significantly higher microhardness values than the bleached-only group (p<0.05). It was concluded that, regardless of the increase in enamel hardness due to the application of fluoride solutions, the treated enamel surface did not prevent the toxic effects caused by the 16% CP gel to odontoblast-like cells.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Diana Gabriela
authors.initials: DG
authors.lastname: Soares
authors.forename: Ana Paula Dias
authors.initials: AP
authors.lastname: Ribeiro
authors.forename: Adriano Fonseca
authors.initials: AF
authors.lastname: Lima
authors.forename: Nancy Tomoko
authors.initials: NT
authors.lastname: Sacono
authors.forename: Josimeri
authors.initials: J
authors.lastname: Hebling
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: de Souza Costa
mesh_terms: D000469:Alkaline Phosphatase / Q000187:drug effects; D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents; D003743:Dental Enamel / Q000187:drug effects*; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects*; D003786:Dental Pulp Cavity / Q000187:drug effects; D003804:Dentin / Q000187:drug effects; D005459:Fluorides / Q000494:pharmacology*; D006244:Hardness; D009804:Odontoblasts / Q000187:drug effects / Q000378:metabolism; D010545:Peroxides / Q000633:toxicity*; D011419:Propidium; D020011:Protective Agents / Q000494:pharmacology*; D013385:Succinate Dehydrogenase / Q000187:drug effects; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000633:toxicity*; D014508:Urea / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: D004396:Coloring Agents; D010545:Peroxides; D020011:Protective Agents; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D011419:Propidium; D014508:Urea; D013385:Succinate Dehydrogenase; D000469:Alkaline Phosphatase; D005459:Fluorides