title: Influence of tooth age and etching time on the microtensile bond strengths of adhesive systems to dentin.
abstract: OBJECTIVE
  1. To evaluate the effect of tooth age on the microtensile bond strengths (µTBS) of various adhesive systems to dentin; 2. To evaluate the effect of different etching times on the microtensile bond strengths of different adhesive systems to young vs mature dentin.
  
  
  METHODS
  One hundred twenty intact human teeth were mechanically ground to expose midcoronal dentin and were randomly assigned to three groups (n = 40) according to subjects' age in years: 15 to 25, 35 to 45, and >= 55. Within each group, specimens were further randomized into 8 subgroups according to adhesive (etch-and-rinse 3- and 2-step; self-etching 2- and 1-step) and etching time (manufacturer instructions vs extended). Resin composite was applied to the treated surfaces, and after 24 h, all specimens were processed for microtensile bond strength testing. Data were analyzed by factorial ANOVA and Tukey's test (p = 0.05).
  
  
  RESULTS
  µTBS values ranged from 10.9 MPa (2-step self-etching, extended etching time, age group 15 to 25) to 50.7 MPa (1-step self-etching, extended etching time, age group >= 55). With only one exception, tooth age and etching time had no significant effect on the bond strengths of the adhesives to dentin. The 2-step self-etching system had lower bond strengths than the other systems, regardless of etching time or tooth age.
  
  
  CONCLUSIONS
  Tooth age and etching time did not affect the dentin bond strengths of the adhesives tested.
authors.affiliation: Department of General Dentistry and Oral Medicine, University of Louisville, School of Dentistry, Louisville, KY 40202, USA. gcolive01@louisville.edu
authors.forename: Greice C B
authors.initials: GC
authors.lastname: Oliveira
authors.forename: Gustavo M S
authors.initials: GM
authors.lastname: Oliveira
authors.forename: André V
authors.initials: AV
authors.lastname: Ritter
authors.forename: Harald O
authors.initials: HO
authors.lastname: Heymann
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Swift
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Yamauchi
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000293:Adolescent; D000328:Adult; D000375:Aging; D000704:Analysis of Variance; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin / Q000502:physiology*; D017220:Dentin-Bonding Agents; D006801:Humans; D008875:Middle Aged; D019279:Resin Cements; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D013997:Time Factors; D014070:Tooth / Q000502:physiology*; D055815:Young Adult
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements