Influence of titanium dioxide nanotubes with alkyl ammonium alkyl bromide on the physicochemical properties and adhesion of experimental adhesive resins to dentin

Objective: This study evaluated the effect of the incorporation of titanium dioxide nanotubes with alkyl trimethyl ammonium bromide (ntTiO 2 /ATAB) into experimental adhesive resins on their physicochemical properties and adhesion to dentin. Materials & methods: The experimental adhesive resins were formulated with 66.66 wt% Bis-GMA and 33.33 wt% HEMA, photoinitiator with addition of ntTiO 2 /ATAB (1:1) in different concentrations: G 1% , G 2.5% , and G 5% . One groups with no ntTiO 2 /ATAB addition was used as control (G 0% ). An optical tensiometer was used to analyze the contact angle (COA) by the sessile drop method (distilled water and alpha-bromonaphthalene) (n = 5), while the surface free energy (SFE) was calculated using Owens-Wendt-Rabel-Kaelble method. Flexural strength (FS) test (three-point bending) of polymerized adhesive samples was performed according to ISO 4049:2019 (n = 10) after 24 h or one year of water storage at 37 degrees C, as well as for the microtensile bond strength (mu TBS) test, in which a commercial adhesive (G SBMP ) was also used as control (n = 10). The adhesive -dentin interfaces were evaluated by scanning electron microscopy and X-ray spectrometry (n = 5). Data were analyzed by one-way (COA and SFE), two-way (FLE and mu TBS) ANOVA and Tukey 's test ( alpha = 0.05). Results: G 5% showed the highest COA with nonpolar liquid and higher SFE than G 0% . The G 5% showed decreased FS compared to G 0% . The mu TBS of both controls (G 0% and G SBMP ) decreased after one year. TiO 2 /ATAB-containing adhesives to dentin showed no significant decrease after one year. All adhesives formed hybrid layer and the resin tags inside the dentinal tubules. Conclusions: The incorporation of 1 and 2.5% of ntTiO 2 /ATAB into experimental adhesive resins did not impar the SFE. After one year, any concentration of ntTiO 2 /ATAB reduced the FS compared with control, but did not impair the mu TBS.