Titanium dioxide nanoparticles addition to a conventional glass-ionomer restorative: Influence on physical and antibacterial properties

Objectives: The aim of this study was to evaluate the addition of titanium dioxide (TiO2) nanoparticles to a conventional glass-ionomer (GI) on physical and antibacterial properties. Methods: TiO2 nanoparticles were incorporated into the powder component of Kavitan (R) Plus (SpofaDental, Czech Republic) at 3%, 5% and 7% (w/w). Unblended powder was used as control. Fracture toughness, compressive strength, flexural strength and microtensile bond strength were evaluated using a universal testing machine. Surface microhardness was measured using Vickers microhardness tester. Setting time was determined as specified in the ISO standard. The antibacterial activity was evaluated using direct contact test against Streptococcus mutans. Fluoride release and SEM analysis were carried out. Data were analysed using ANOVA and Tukey's test. Results: GI-containing 3% and 5% (w/w) TiO2 nanoparticles improved the fracture toughness, flexural strength and compressive strength compared to the unmodified GI. However, a decrease in the mechanical properties was found for GI-containing 7% (w/w) TiO2 nanoparticles. GI-containing 5% and 7% (w/w) TiO2 nanoparticles compromised the surface microhardness. Setting time of GI-containing TiO2 nanoparticles decreased but the values remained within ISO limits. The addition of TiO2 nanoparticles to the conventional GI did not compromise its bond strength with dentine or fluoride release of the GI. GI-containing TiO2 nanoparticles possessed a potent antibacterial effect. Conclusions: GI-containing 3% (w/w) TiO2 nanoparticles is a promising restorative material with improved mechanical and antibacterial properties. This novel experimental GI may be potentially used for higher stress-bearing site restorations such as Class I and II. (C) 2011 Elsevier Ltd. All rights reserved.