Titanium dioxide nanotubes with triazine-methacrylate monomer to improve physicochemical and biological properties of adhesives

Objective. Formulate experimental adhesives containing titanium dioxide nanotubes (ntTiO(2)) or titanium dioxide nanotubes with a triazine-methacrylate monomer (nt-TiO2:TAT) and evaluate the effect of these fillers on the physical, chemical, and biological properties of the adhesives. Methods. First, nt-TiO2 were synthesized via a hydrothermal method. The nt-TiO2 were mixed with a triazine-methacrylate monomer (TAT) to formulate nt-TiO2:TAT, which were characterized by transmission electron microscopy (TEM). The nt-TiO2, TAT, and nt-TiO2:TAT were evaluated via Fourier Transform Infrared, Ultraviolet-visible, and micro-Raman spectroscopies. An experimental adhesive resin was formulated with bisphenol A glycerolate dimethacrylates, 2-hydroxyethyl methacrylate, and photoinitiator/co-initiator system. ntTiO(2) or nt-TiO2:TAT were incorporated at 2.5 wt.% and 5 wt.% in the adhesive. The base resin without nt-TiO2 or nt-TiO2:TAT was used as a control group. The adhesives were evaluated for antibacterial activity, cytotoxicity, polymerization kinetics, degree of conversion (DC), Knoop hardness, softening in solvent (AKHN%), ultimate tensile strength (UTS), 24 hand 1 yearmicrotensile bond strength (mu-TBS). Results. TEM confirmed the nanotubular morphology of TiO2. FTIR, UV-vis, and micro-Raman analyses showed the characteristic peaks of each material, indicating the impregnation of TAT in the nt-TiO2. Adhesives with nt-TiO2:TAT showed antimicrobial activity against biofilm formation compared to control (p < 0.05), without differences in the viability of planktonic bacteria (p > 0.05). All groups showed high percentages of pulp cell viability. The polymerization kinetics varied among groups, but all presented DC above 50%. The addition of 5 wt.% of nt-TiO2 and both groups containing nt-TiO2:TAT showed higher values of Knoop hardness compared to the control (p < 0.05). The groups with nt-TiO2:TAT presented lower Delta KHN% (p < 0.05) and higher UTS (p < 0.05) than the control group. After one year, the group with 5 wt.% of nt-TiO2, as well as both groups containing nt-TiO2:TAT, showed higher mu-TBS than the control (p < 0.05). Significance. The mixing of a triazine-methacrylate monomer with the nt-TiO2 generated a filler that improved the physicochemical properties of the adhesive resins and provided antibacterial activity, which could assist in preventing carious lesions around tooth-resin interfaces. The set of physical, chemical, and biological properties of the formulated polymer, together with the greater stability of the bond strength over time, make nt-TiO2:TAT a promising filler for dental adhesive resins. (C) 2020 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Automated summary

This study aimed to formulate experimental adhesives containing titanium dioxide nanotubes or titanium dioxide nanotubes with a triazine-methacrylate monomer and evaluate their effects on the properties of the adhesives. Results showed that adhesives with nt-TiO2:TAT exhibited good antibacterial activity and hardness, potentially providing better cariostatic effects around tooth-resin interfaces.