The influence of neutral MDP-Na salt on dentin bond performance and remineralization potential of etch-&-rinse adhesive

Abstract Objectives. To investigate the effect of neutral 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-Na salt on the dentin bond strength and remineralization potential of etch-&-rinse adhesive. Methods. Two experimental etch-&-rinse adhesives were prepared by integrating varying weight percentages (0wt%, 20wt%) of neutral MDP-Na into a base primer. A commercial etch-&-rinse adhesive Adper Single Bond 2 (SB, 3M ESPE) was used as control. Following this, microtensile bond strength (MTBS) was evaluated after subjecting the samples to 24 h of water storage or a 6-month incubation in artificial saliva. Fourier-transformed infrared spectrometry was used for assessment of the degree of conversion of the experimental adhesives and the adsorption properties of MDP-Na on the dentin organic matrix. Furthermore, the efficacy of neutral MDP-Na in facilitating the remineralization of two-dimensional collagen fibrils and the adhesive–dentin interface was investigated using transmission electron microscopy and selected-area electron diffraction. Results. The addition of MDP-Na into the primer increased both the short- and long-term MTBS of the experimental adhesives (p = 0.000). No difference was noted in the degree of conversion between the control, 0 wt% and 20 wt% MDP-Na-containing groups (p = 0.336). The intra- and extra-fibrillar remineralization of the two-dimensional collagen fibril and dentin bond hybrid layer was confirmed by transmission electron microscopy and selected-area electron diffraction when the primer was added with MDP-Na. Conclusions. The use of neutral MDP-Na results in high-quality hybrid layer that increase the dentin bond strength of etch-&-rinse adhesive and provides the adhesive with remineralizing capability. This approach may represent a suitable bonding strategy for improving the dentin bond strength and durability of etch-&-rinse adhesive.