title: Effect of priming time on tensile bond strength to bovine teeth and morphologic structure of interfaces created by self-etching primers.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effect of priming time on bovine enamel and dentin adhesion promoted by self-etching primer systems.
  
  
  METHODS
  Two commercial self-etching primer systems, Clearfil SE Bond (SE) and Unifil Bond (UB), were used. Bovine enamel and dentin were treated with each system with various priming times (5, 20, and 60 seconds), and the tensile bond strength was measured. Scanning electron microscopic (SEM) observation was also performed to examine the effect of priming time on the morphology of the resin-tooth interface.
  
  
  RESULTS
  The tensile bond strength to enamel ranged from 10.6 to 14.3 MPa, and no statistically significant difference was detected among products or priming times. To dentin, UB showed the statistically significantly lowest tensile bond strength when primed for 5 seconds, 6.9 +/- 1.1 MPa, but there was no significant difference between the groups primed for 20 and 60 seconds, 13.5 +/- 4.1 MPa and 13.8 +/- 4.6 MPa, respectively. SE created tensile bond strengths ranging from 13.9 to 15.7 MPa and showed no effect of priming time on dentin adhesion. SEM observation revealed that resin penetrated into both enamel and dentin more deeply with extension of priming time.
  
  
  CONCLUSIONS
  Priming times longer than those recommended by the manufacturers did not influence the tensile bond strength to enamel and dentin when using two commercial self-etching primers. In contrast, a shortened priming time, 5 seconds, carried a risk of decreasing dentin adhesion, although it had no adverse effect on enamel adhesion.
authors.affiliation: Department of Operative Dentistry, Okayama University Dental School, 2-5-1 Shikata, Okayama 700-8525, Japan. kousuke@dent.okayama-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Itou
authors.forename: Y
authors.initials: Y
authors.lastname: Torii
authors.forename: T
authors.initials: T
authors.lastname: Takimura
authors.forename: K
authors.initials: K
authors.lastname: Chikami
authors.forename: K
authors.initials: K
authors.lastname: Ishikawa
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D013223:Statistics as Topic; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
chemical_list: C029849:Clearfil Bonding Agent; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C407402:Unifil Bond