Bonding efficacy of a low-pH one-step adhesive system Adper Prompt L-Pop

Abstract

This study was aimed to evaluate the bonding efficacy of a one-step adhesive system Adper Prompt L-Pop. Inmicrotensile bond testing to human dentin, 23 out of 30 specimens were broken down at the bonding interfaceduring trimming of the specimens. The result was 2.7±5.89 MPa or 11.6±6.87 MPa when n=30 or n=7, respectively. FE-SEM observation of the fractured surfaces showed that most failures occurred at the interface between adhesive resin and resin composite, and void-like structures were appeared on the adhesive resin surfaces. FE-SEM figures of the bonding interfaces revealed the tight adhesions to enamel, sound dentin and caries-affecteddentin, while voids formation was found at the interface between adhesives and composites. At the interface withdentin, there was a hybrid layer approximately 2-3μm thick. In TEM observation, the oxygen inhibition layerswere created in the superficial adhesive resin layer. Due to a low pH of approximately 0.9 and a strong demineraliz-ing effect, this system might create a hybrid layer composed of mainly collagen and impregnated monomers.However, it was suggested that its highly hydrophilic and acidic properties likely caused poor bonding with the resin composite.