Effect of Titanium Dioxide (TiO₂) Incorporation on the Properties of Glass Ionomer Cements: A Systematic Review

This systematic review aimed to investigate the effect of titanium dioxide (TiO₂) incorporation on the mechanical, physicochemical, and biological properties of conventional glass ionomer cements (GICs). A systematic search was conducted in June 2026 in PubMed, Scopus, Embase, Web of Science and WorldCat databases. Search terms included combinations of glass ionomer AND titanium dioxide OR TiO₂ OR titanium oxide OR titanium nanotubes OR titanium nanoparticles. The study selection process followed the PRISMA guideline and was organized according to the PECO framework. The search yielded the identification of 475 articles, of which 34 met the eligibility criteria. The included studies investigated different TiO₂ forms, concentrations, and commercial GIC formulations. Many studies reported improvements in compressive strength, surface microhardness, fracture toughness, and antibacterial activity following TiO₂ incorporation. However, the findings were heterogeneous. Several studies reported no statistically significant differences or contradictory outcomes, particularly regarding flexural strength, fluoride release, cytocompatibility, and antibacterial performance. Beneficial effects were most frequently observed at TiO₂ concentrations between 3 and 5 wt%, whereas higher concentrations were occasionally associated with nanoparticle agglomeration and reduced material performance. Variability among studies was likely influenced by differences in TiO₂ characteristics, concentration, testing protocols, and GIC formulation. Overall, TiO₂ incorporation appears to be a promising approach for enhancing selected properties of conventional GICs. However, further standardized studies are required to confirm the consistency and clinical relevance of these effects.