title: The Effect of 3% Phosphate Ascorbyl Gel on Bond Strength of Composite Resin to Enamel treated with 35% Hydrogen Peroxide.
abstract: To evaluate the effect of 3% phosphate ascorbyl gel (PA) in different times onto the microshear bond strength of composite resin (CR) to bovine enamel treated with 35% hydrogen peroxide (HP).
  
  
  
  Thirty enamel blocks of bovine incisors were made and divided into 5 groups (n = 6) with three specimens per group (n = 18), according to treatment: G1= No bleaching + CR; G2 = HP + CR after 15d; G3 = HP + CR after 24 hours; G4 = HP + PA (15 min) + CR after 24 hours; G5 = HP + PA (2 hours) + CR after 24 hours. The resin cylinders were made by Tygon matrices. Microshear bond strength test was performed using universal testing machine with a 50N load at a speed of 0.5 mm/min. Fracture modes were assessed by a stereomicroscope 40 ×. Microshear bond strength values were submitted to the analysis of variance (ANOVA) one-way and Tukey test (p < 0.05).
  
  
  
  G1 had significant results when compared to G3 and G5 (p < 0.01). However, G2, G3, G4 and G5 have showed no significant differences among groups (p > 0.05). Failure modes were categorized into adhesive (90%) and mixed (10%).
  
  
  
  The use of 3% phosphate ascorbyl gel for 15 minutes was able to improve bond strength of composite resin to bleached bovine enamel, but when 3% phosphate ascorbyl gel was applied during 40 minutes it negatively interfered in the adhesion of the resin to bleached bovine enamel.
authors.affiliation: Department of Dentistry, Federal University of Maranhão São Luís, Maranhão, Brazil.
authors.forename: Milena de Fátima Schalcher
authors.initials: Mde F
authors.lastname: de Castro
authors.affiliation: Department of Dentistry, Federal University of Maranhão São Luís, Maranhão, Brazil.
authors.forename: Alice Carvalho
authors.initials: AC
authors.lastname: Silva
authors.affiliation: Department of Dentistry, Federal University of Maranhão São Luís, Maranhão, Brazil.
authors.forename: Marcela Mayana Pereira
authors.initials: MM
authors.lastname: Franco
authors.affiliation: Department of Dentistry, Federal University of Maranhão São Luís, Maranhão, Brazil.
authors.forename: Ana Paula Brito
authors.initials: AP
authors.lastname: Silva
authors.affiliation: Deparment of Dentistry, CEUMA University, São Luís Maranhão, Brazil.
authors.forename: Fausto da Silva
authors.initials: Fda S
authors.lastname: Bramante
authors.affiliation: Deparment of Dentistry, CEUMA University, São Luís Maranhão, Brazil.
authors.forename: Monica Barros
authors.initials: MB
authors.lastname: da Silva
authors.affiliation: Adjunctive Professor, Department of Dentistry, Universidade Federal do Maranhão, Av. Portugueses s/n, Campus Universitário Bacanga, 65085-580, São Luís, Maranhão, Brazil, Phone: 55 98 3272-8577, e-mail: darlonmartins@yahoo.com.br.
authors.forename: Darlon Martins
authors.initials: DM
authors.lastname: Lima
authors.affiliation: Department of Dentistry, Federal University of Maranhão São Luís, Maranhão, Brazil.
authors.forename: Adriana de Fátima Vasconcelos
authors.initials: Ade F
authors.lastname: Pereira
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000737:chemistry / Q000494:pharmacology*; D014867:Water / Q000737:chemistry
chemical_list: D000975:Antioxidants; D003188:Composite Resins; D003764:Dental Materials; C444701:Filtek Z250; D019279:Resin Cements; D058205:Tooth Bleaching Agents; D014867:Water; C011669:ascorbate-2-phosphate; C041330:Scotchbond; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid
keywords: Antioxidants; Tooth bleaching; Hydrogen peroxide; Composite resins; Shear strength.