title: Effect of application mode on interfacial morphology and chemistry between dentine and self-etch adhesives.
abstract: OBJECTIVE
  To investigate the influence of application mode on the interfacial morphology and chemistry between dentine and self-etch adhesives with different aggressiveness.
  
  
  METHODS
  The occlusal one-third of the crown was removed from un-erupted human third molars, followed by abrading with 600 grit SiC under water. Rectangular dentine slabs were prepared by sectioning the tooth specimens perpendicular to the abraded surfaces. The obtained dentine slabs were treated with one of the two one-step self-etch adhesives: Adper Easy Bond (AEB, pH∼2.5) and Adper Prompt L-Pop (APLP, pH∼0.8) with (15s, active application) or without (15s, inactive application) agitation. The dentine slabs were fractured and the exposed adhesive/dentine (A/D) interfaces were examined with micro-Raman spectroscopy and scanning electron microscopy (SEM).
  
  
  RESULTS
  The interfacial morphology, degree of dentine demineralization (DD) and degree of conversion (DC) of the strong self-etch adhesive APLP showed more significant dependence on the application mode than the mild AEB. APLP exhibited inferior bonding at the A/D interface if applied without agitation, evidenced by debonding from the dentine substrate. The DDs and DCs of the APLP with agitation were higher than those of without agitation in the interface, in contrast to the comparable DD and DC values of two AEB specimen groups with different application modes. Raman spectral analysis revealed the important role of chemical interaction between acid monomers of self-etch adhesives and dentine in the above observations.
  
  
  CONCLUSIONS
  The chemical interaction with dentine is especially important for improving the DC of the strong self-etching adhesive at the A/D interface. Agitation could benefit polymerization efficacy of the strong self-etch adhesive through enhancing the chemical interaction with tooth substrate.
authors.affiliation: University of Missouri-Kansas City School of Dentistry, 650 E 25th Street, Kansas City, MO 64108, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D055598:Chemical Phenomena; D003188:Composite Resins; D003648:Decalcification Technique; D001840:Dental Bonding / Q000379:methods*; D045662:Dental Etching; D003799:Dental Stress Analysis; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D058105:Polymerization; D019279:Resin Cements; D013059:Spectrum Analysis, Raman; D013382:Subtraction Technique; D013718:Tensile Strength; D014732:Vibration
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C408584:Prompt L-Pop; D019279:Resin Cements; C584661:easy bond