Influence of conditioning time on enamel adhesion.
OBJECTIVE
The aim of this study was to calculate enamel bond strengths of 4 self-etch adhesives in function of conditioning time.


METHODS
Sixty proximal surfaces of 30 extracted human molars were roughened and assigned to 4 self-etch adhesives: AdheSE (Ivoclar Vivadent), Adper Prompt L-Pop (3M Espe), Clearfil SE Bond (Kuraray America), and Tyrian SPE/One-Step Plus (Bisco). Prime & Bond NT (Dentsply) was used as the total-etch control. For 30 surfaces, the adhesives were applied per the manufacturers' directions. For the remaining 30, enamel was conditioned for twice the time recommended by the manufacturer. Buildups were constructed with Filtek Z250 (3M ESPE). Bonded specimens were sectioned in sticks and tested to tensile failure. Data were analyzed with 2-way ANOVA and Duncan's test at P < .05. The pH of the self-etch solutions and the phosphoric acid gel was measured with a pH meter. A correlation coefficient was computed to measure the linear association between pH and bond strengths.


RESULTS
Tyrian SPE and Prime & Bond NT, the adhesives whose acidic conditioners yielded the lowest pH, ranked in the highest subset regardless of application time. AdheSE and Clearfil SE Bond, which had the highest pH, were the only adhesives for which double application time resulted in statistically higher bond strengths than the recommended time. When means were pooled for application time, Tyrian SPE and Prime & Bond NT resulted in bond strengths that were significantly higher than those of the remaining adhesives. AdheSE resulted in statistically lower bond strengths than any other adhesive. A significant correlation was found between pH and mean bond strengths.


CONCLUSIONS
Doubling the enamel conditioning time might increase bond strengths for specific self-etch adhesives.
Perdigão
Jorge
J
University of Minnesota, Division of Operative Dentistry, Department of Restorative Sciences, 8-450 Moos Tower, 515 SE Delaware Street, Minneapolis, MN 55455, USA. perdi001@umn.edu
Gomes
George
G
Lopes
Maria Manuela
MM
D000134:Acid Etching, Dental / Q000379:methods*; D000180:Acrylic Resins / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D010756:Phosphoric Acids / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors
D000180:Acrylic Resins; C489662:AdheSE cement; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; C408584:Prompt L-Pop; D019279:Resin Cements; C481138:Tyrian SPE