Effect of polydopamine incorporated dentin adhesives on bond durability

Abstract

Inspired by mussel-adhesion phenomenon in wet environment, polydopamine (PDA) was tried in recent research reports to improve the dentin adhesive interface with better strength and durability. The aim of this study was to comparatively evaluate the effect of PDA incorporated dentin adhesive systems and conventional adhesive systems on degree of conversion (DC), resin dentin bond strength (SBS), durability and MMP inhibition activity. In this study, PDA was incorporated in total-etch adhesive system (TE) and self-etch adhesive systems (SE) and degree of conversion (DC%) was evaluated using Fourier transform infrared spectroscopy. Dentin slabs obtained from 160 non-carious human premolars were divided into the following: Group 1, TE; Group 2, PDA incorporated TE adhesive (TEP); Group 3, SE; Group 4, PDA incorporated SE adhesive (SEP) and bonding procedures were performed. Samples were stored for either 24 h or 6 months, after which shear bond strength and resin dentin interface was evaluated using universal testing machine and confocal laser scanning microscopy (CLSM), respectively. The zymographic assay was performed on protein extracts obtained from dentin powder treated with each of the adhesives or with or without PDA followed by functional activity assay for MMP-2 and -9. Statistical analysis was done with two-way analysis of variance and Student t-test at significance level as p < 0.05. There was statistically no significant difference in the DC% between PDA incorporated adhesives and control. No significant reduction in SBS was observed in TEP and SEP in pre- and post-aging while CLSM showed better penetration depth of resin and lesser degradation of hybrid layer on aging. Significantly lesser MMP activity was seen in PDA incorporated adhesives qualitatively and quantitatively on zymographic and functional MMP activity assay respectively. HIGHLIGHTS Catechol moieties present in polydopamine provide anti-collagenolytic activity, MMP inhibitory activity and enhances wet adhesion. Polydopamine incorporated dentin bonding systems attempts to provide stable resin dentin bond with increased bond durability. It can inhibit both proteolytic and hydrolytic breakdown of resin–dentin bond degradation.