Novel riboflavin/VE-TPGS modified universal dentine adhesive with superior dentine bond strength and self-crosslinking potential

Objective. To modify a universal dentine adhesive with different concentrations of riboflavin and D-Alpha 1000 Succinate polyethylene (VE-TPGS) as a chemical enhancer and to assess the micro-tensile bond strength (24h/12 months), determine resin penetration, measurement of intermolecular interactions and cytotoxicity. Materials and methods. An experimental adhesive system based on bis-GMA, HEMA and hydrophobic monomer was doped with RF0.125 (RF - Riboflavin) or RFNE-TPGS ((0.25/0.50)) and submitted to mu TBS evaluation. Resin dentine slabs were prepared and examined using SEM and TEM. Adhesion force was analysed on ends of AFM cantilevers deflection. Quenched peptide assays were performed using fluorescence scanner and wavelengths set to 320 nm and 405 nm. Cytotoxicity was assessed using human peripheral blood mononuclear cell line. Molecular docking studies were carried out using Schrodinger small-molecule drug discovery suite 2018-2. Data from viable cell results was analyzed using one-way ANOVA. Bond strength values were analysed by two-way ANOVA. Nonparametric results were analyzed using a Kruskal-Wallis test at a 0.05 significance level. Results. RF/VE-TPGS(0.25) groups showed highest bond strength results after 24-h storage in artificial saliva (p <0.05). RFNE-TPGS(0.50) groups showed increased bond strength after 12-months of ageing. RF/VE-TPGS modified adhesives showed appreciable presence of a hybrid layer. Packing fraction indicated solid angle profiles describing well sized density and topology relations for the RFNE-TPGS adhesives, in particular with the RFNE-TPGS(0.50) specimens. Qualitative analysis of the phenotype of macrophages was prominently CD163+ in the RF/VE-TPGS(0.50). Both the compounds showed favourable negative binding energies as expressed in terms of 'XP GScore'. Conclusion. New formulations based on the incorporation of RFNE-TPGS in universal adhesives may be of significant potential in facilitating penetration, distribution and uptake of riboflavin within the dentine surface. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.