title: Effects of mechanical properties of adhesive resins on bond strength to dentin.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the relationship between the micro-tensile bond strength to dentin and mechanical properties of the cured adhesive resins.
  
  
  METHODS
  Coronal dentin surfaces of extracted human teeth were treated with four commercial self-etching priming systems (Clearfil SE Bond; UniFil Bond; Tokuso Mac-Bond II; and Imperva Fluoro Bond) and bonded with a resin composite. After 24h storage in water at 37 degrees C, the bonded specimens were trimmed and subjected to micro-tensile bond strength testing at a cross-head speed of 1mm/min. Debonded surfaces were observed under a FE-SEM. For testing mechanical properties, 0.7-mm thick slabs of each adhesive resin were prepared, light-cured, and stored dry at the room temperature for 24h. After trimming, ultimate micro-tensile strength was measured. The nano-hardness and Young's modulus were also evaluated using cured adhesives that were prepared in the same manner as described above.
  
  
  RESULTS
  The micro-tensile bond strengths to dentin and ultimate micro-tensile strengths of the resins were not significantly different among all systems (P>0.05). However, the nano-hardness and Young's modulus of Clearfil SE Bond and Imperva Fluoro Bond adhesive resins were significantly higher than those of UniFil Bond and Tokuso Mac-Bond II resins (P<0.05). The micro-tensile bond strength significantly correlated with the ultimate micro-tensile strength of the resins (r(2)=0.77; P<0.05), but was not correlated with the nano-hardness or Young's modulus (P>0.05). SEM observation of the debonded surfaces revealed a mixed type of fracture with a combination of interfacial and cohesive failure within the adhesive resin.
  
  
  CONCLUSIONS
  The four self-etching priming systems exhibited similar dentin bond strengths, which also correlates with the ultimate strength of the adhesive resins.
authors.affiliation: Department of Oral Health Science, Hokkaido University School of Dentistry, North 13, West 7, Kita-ku, Sapporo 060-8586, Japan. akiko@den.hokudai.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Uno
authors.forename: P N R
authors.initials: PN
authors.lastname: Pereira
authors.forename: H
authors.initials: H
authors.lastname: Sano
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D000473:Alkanes / Q000737:chemistry; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004548:Elasticity; D006244:Hardness; D006801:Humans; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000473:Alkanes; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C074806:Imperva-Bond; D008298:Maleates; D019279:Resin Cements; C115514:Tokuso Mac Bond; C407402:Unifil Bond; D014867:Water