Glass Ionomer Cements with Halloysite-CHX: Physicochemical Properties, Antimicrobial Activity, Cell Viability

This study evaluated the physicochemical, cell viability, and antimicrobial properties of conventional glass ionomer cement (GIC) modified by the incorporation of halloysite nanotubes (HNT) doped with chlorhexidine (CHX). HNT-CHX was added to GIC at concentrations of 2.5% and 5% by weight, forming three experimental groups: a control group (GIC only), a group with 2.5% HNT-CHX, and another with 5% HNT-CHX. Hourglass-shaped specimens (n=10) were used to measure cohesive strength and elastic modulus, while fractured specimens were subjected to microhardness testing (n = 5). To assess the alkalinizing activity (pH) and the release of F-, Ca+2, and PO4-3 ions (n = 3), discs were prepared for CHX release analysis by UV-vis after 24 hours. Antimicrobial activity was tested against S. mutans biofilm (CFU/ml), and material cell viability was determined using the MTT assay. Results showed that the 5% HNT-CHX group presented the lowest cohesive strength, while the 2.5% and 5% HNT-CHX groups displayed modulus values similar to the control and did not affect microhardness. All groups exhibited an acidic pH with the control group releasing higher levels of F-, Ca+2, and PO4 -3 ions. The HNT-CHX 2.5% and HNT-CHX 5% groups reduced fluoride ion release compared to the control (GIC). The 5% HNT-CHX group showed the highest levels of free CHX and demonstrated bactericidal activity against S. mutans in CFU analysis. None of the materials presented cytotoxicity. In conclusion, incorporating 2.5% and 5% HNT-CHX affected the mechanical properties and ion release of the GIC. HNT-CHX 5% group exhibited antimicrobial against S. mutans.