TiO₂ nanotubes improve physico-mechanical properties of glass ionomer cement

The aim of this study was to determine the physico-mechanical properties of a high viscosity glass ionomer cement (GIC) reinforced with TiO₂ nanotubes (TiO₂-nt).

TiO₂-nt was incorporated into the GIC powder components (Ketac Molar EasyMix™) in concentrations of 0% (control group), 3%, 5%, 7% by weight. Compressive strength (n = 10/group), three point bending for flexural strength (n = 18/group), microshear bond strength to dentin and failure mode (n = 20/group), and surface roughness and weight loss before and after brushing simulation (30,000 cycles) (n = 8/group) were evaluated. Data were submitted to Shapiro-Wilk, ANOVA, Tukey and Chi-square tests (α ≤ 0.05).

Addition of 5% of TiO₂-nt into GIC presented the highest values for compressive strength and differed from the control, 3% and 7% groups (p = 0.023). There were no significant differences in flexural strength (p = 0.107) and surface roughness before and after the dental brushing (p = 0.287) among the groups. GIC added with 5% TiO₂-nt showed the lowest weight loss values (p = 0.01), whereas the control, 3% or 5% TiO₂-nt groups presented similar microshear bond strength values (p ≥ 0.05). The 5% TiO₂-nt group featured higher microshear bond strength than the 7% TiO₂-nt group (p = 0.034). Cohesive in material was the most representative failure mode for all groups.

The incorporation of TiO₂-nt did not affect GIC's adhesiveness to dentin, but improved its compressive strength at 5%. Furthermore, TiO₂-nt decreased the percentage of weight loss after GIC's surface wear.