title: Effect of non-vital tooth bleaching on microleakage of coronal access restorations.
abstract: This study evaluated the effect of non-vital tooth bleaching on microleakage of composite resin/bovine tooth interface at different post-bleaching times. A total of 320 teeth were cleaned. A pulp chamber access cavity was made at the lingual surface of each tooth. The teeth were randomly divided into four groups: SPH - sodium perborate + 30% hydrogen peroxide; SPW - sodium perborate + distilled water; CP-37% carbamide peroxide; and CON-distilled water (control). The bleaching agents were replaced every 7 days, over 4 weeks. Following bleaching procedures, the groups were divided into four subgroups (n = 20), according to the post-bleaching times: 0 (baseline), 7, 14 and 21 days. After that, the cavities were restored with an adhesive system (Single Bond; 3M Co., St Paul, MN, USA) and a composite resin (Z100/3M). The specimens were thermocycled, stained with 2% methylene blue solution (pH 7), and sectioned longitudinally. The teeth were evaluated blind and independently by three previously calibrated examiners, to provide representative scores. The data were submitted to Kruskal-Wallis and multiple comparison tests (alpha=0.05). At baseline and 7 days, the SPH group showed a higher degree of dye penetration than the CON (P=0.04). At 14 and 21 days, there were no differences among groups. The association of sodium perborate with 30% hydrogen peroxide or with water may affect the sealing ability of composite resin restorations performed up to 7 days after bleaching procedures.
authors.affiliation: Department of Restorative Dentistry, Piracicaba School of Dentistry, State University of Campinas, São Paulo, Ribeirão Peeto School of Dentistry, USP, São Paulo, Brazil.
authors.forename: E C N
authors.initials: EC
authors.lastname: Teixeira
authors.forename: A T
authors.initials: AT
authors.lastname: Hara
authors.forename: C P
authors.initials: CP
authors.lastname: Turssi
authors.forename: M C
authors.initials: MC
authors.lastname: Serra
mesh_terms: D000268:Adhesiveness / Q000187:drug effects; D000818:Animals; D001881:Borates / Q000633:toxicity; D000077463:Carbamide Peroxide; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods; D003763:Dental Leakage / Q000139:chemically induced*; D003793:Dental Restoration, Permanent; D004338:Drug Combinations; D006861:Hydrogen Peroxide / Q000633:toxicity; D010545:Peroxides / Q000633:toxicity; D013997:Time Factors; D014073:Tooth Bleaching / Q000009:adverse effects* / Q000379:methods; D014508:Urea / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: D001881:Borates; D003188:Composite Resins; D004338:Drug Combinations; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C027707:sodium perborate