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

OBJECTIVE

Formulate experimental adhesives containing titanium dioxide nanotubes (nt-TiO) or titanium dioxide nanotubes with a triazine-methacrylate monomer (nt-TiO:TAT) and evaluate the effect of these fillers on the physical, chemical, and biological properties of the adhesives.

METHODS

First, nt-TiO were synthesized via a hydrothermal method. The nt-TiO were mixed with a triazine-methacrylate monomer (TAT) to formulate nt-TiO:TAT, which were characterized by transmission electron microscopy (TEM). The nt-TiO, TAT, and nt-TiO: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. nt-TiO or nt-TiO:TAT were incorporated at 2.5 wt.% and 5 wt.% in the adhesive. The base resin without nt-TiO or nt-TiO: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 (ΔKHN%), ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μ-TBS).

RESULTS

TEM confirmed the nanotubular morphology of TiO. FTIR, UV-vis, and micro-Raman analyses showed the characteristic peaks of each material, indicating the impregnation of TAT in the nt-TiO. Adhesives with nt-TiO: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-TiO and both groups containing nt-TiO:TAT showed higher values ​​of Knoop hardness compared to the control (p < 0.05). The groups with nt-TiO:TAT presented lower ΔKHN% (p < 0.05) and higher UTS (p < 0.05) than the control group. After one year, the group with 5 wt.% of nt-TiO, as well as both groups containing nt-TiO:TAT, showed higher μ-TBS than the control (p < 0.05).

SIGNIFICANCE

The mixing of a triazine-methacrylate monomer with the nt-TiO 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-TiO:TAT a promising filler for dental adhesive resins.