Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.
The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s.
Department of Operative Dentistry, Nihon University School of Dentistry, Tokyo, Japan.|Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE, USA.
Akimasa
A
Tsujimoto
Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE, USA.
Wayne W
WW
Barkmeier
Department of Operative Dentistry, Nihon University School of Dentistry, Tokyo, Japan.
Toshiki
T
Takamizawa
Department of Restorative Dentistry, Oregon Health & Science University School of Dentistry, Portland, OR, USA.
Hidehiko
H
Watanabe
Department of Adult Restorative Dentistry, University of Nebraska Medical Center College of Dentistry, Lincoln, NE, USA.
William W
WW
Johnson
Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE, USA.
Mark A
MA
Latta
Department of Operative Dentistry, Nihon University School of Dentistry, Tokyo, Japan.
Masashi
M
Miyazaki
D000134:Acid Etching, Dental; D001840:Dental Bonding; D003738:Dental Cements; D003743:Dental Enamel; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000494:pharmacology*; D019279:Resin Cements; D033081:Shear Strength; D013499:Surface Properties
D003738:Dental Cements; D010756:Phosphoric Acids; D019279:Resin Cements
bond durability; phosphoric acid pre-etching; surface free-energy; universal adhesive