title: Influence of postextraction substrate aging on the microtensile bond strength of a dental adhesive system.
abstract: OBJECTIVE
  To investigate the effect of postextraction substrate aging on the microtensile bond strength (muTBS) of an adhesive system (Excite).
  
  
  METHODS
  Sixty sound human third molars were extracted for orthodontic purposes and prepared after the following storage periods in distilled water at 37 degrees C (n = 10): G1 - 1 h; G2 - 24 h; G3 - 7 days; G4 - 30 days; G5 - 1 year; G6 - 2 years. The occlusal surfaces were removed using diamond disks to expose middle dentin and a standardized smear layer was created by polishing with wet 600-grit sandpaper. The adhesive system was applied according to the manufacturer's instructions, and a resin composite block (5 mm in height, Tetric Ceram shade A2/Ivoclar Vivadent) was built in 1-mm increments, each one being light cured for 40 s (600 mW/cm2). After storage in distilled water at 37 degrees C for 24 h, teeth were sectioned to obtain stick-shaped specimens with a cross-sectional area of approximately 0.7 +/- 0.2 mm2. Specimens were submitted to muTBS test in a Kratos universal testing machine at a crosshead speed of 0.5 mm/min. Data were statistically analyzed using one-way ANOVA at a significance level of 5% (p < 0.05)
  
  
  RESULTS
  The mean muTBS in MPa +/- SD were: G1 = 47 +/- 3.1; G2 = 42 +/- 5.1; G3 = 41 +/- 6.4; G4 = 43 +/- 9.8; G5 = 40 +/- 7.0; G6 = 52 +/- 5.7. No statistically significant difference was found among experimental groups.
  
  
  CONCLUSIONS
  Human teeth stored for long periods of time can be used to determine the in vitro muTBS of one-bottle adhesive systems.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227 São Paulo, Brazil. wmiranda@usp.br
authors.forename: Walter G Júnior
authors.initials: WG
authors.lastname: Miranda
authors.forename: Elaine
authors.initials: E
authors.lastname: Placido
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Moura
authors.forename: Paulo E Capel
authors.initials: PE
authors.lastname: Cardoso
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D013718:Tensile Strength; D013997:Time Factors; D014070:Tooth / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C121818:Tetric ceram