On the other hand, in Se mode, the acidic resin monomers are responsible for conditioning and priming the dentin surface by dissolving the smear layer without dissolving calcium phosphate of hydroxyapatite surface, which enables more close chemical interaction with the functional groups of MDP monomers enhancing the chemical bond between adhesive and dentin substrate.[31] For that reasonsreason, the results of µTBS in this study of Single Bond universal adhesive revealed that no difference in the µTBS in both etching modes, which werewas in agreement with preliminary work.[4, 22]
For Adhese Universal adhesive, the results of µTBS showed improved resin-dentin bond strengths when used in the Er mode. Smear layerslayers' presence imposes a physical barrier against resin monomersmonomers' penetration. Phosphoric acid etching process removes the smear layer, advocates demineralization of dentin surface and increases the impregnation of resin monomers.[30] This was also supported by the SEM observations, which revealed a thick hybrid layer formation, fully integrated with the dentin substrate.
However, many other variables in the composition of Single Bond universal adhesive and Adhese Universal adhesive may account for the differences observed between these materials as, for instance, is the presence of the polyalkenoic acid copolymer (PAC) (the so called Vitrebond copolymer). Munoz et al.[23] reported that the Vitrebond...[INCOMPLETE]