Effects of Different Zinc Modulations in Glass Ionomer Cements on Multi-Species Biofilm Formation and Human Tooth Demineralization: An In Vitro Study

Background: Biofilm formation and associated tooth demineralization are key factors influencing the clinical performance of dental materials. Methods: This study compared the antibiofilm and demineralization preventive effects of two zinc-modified glass ionomer cements (Zn-GICs) with a conventional GIC. Disk-shaped specimens of Caredyne Restore (CR), ChemFil Rock (CFR), and Ketac Molar (KM) (n = 6) were evaluated in a multi-species biofilm model using an oral biofilm reactor. Early biofilm formation was analyzed by scanning electron microscopy (after 2 h and 4 h), bacterial accumulation and water-insoluble glucan (WIG) production were quantified (after 12 h). For demineralization assessment, restored human enamel and dentin specimens (n = 6) including an additional resin-based control group (Dura Seal, DS) were subjected to a 14-day biofilm challenge and lesion depth was measured using swept-source optical coherence tomography and confocal microscopy. Results: CR showed significantly lower bacterial accumulation and WIG production than the other materials (p < 0.05). CFR demonstrated lower bacterial levels than KM (p < 0.05), whereas no significant differences were observed between CFR and KM in WIG production (p > 0.05). CR produced the shallowest enamel and dentin lesions, whereas DS exhibited the deepest (p < 0.05); however, no statistically significant differences were observed between CFR and KM in lesion depth (p > 0.05). Conclusions: CR demonstrated superior biofilm suppression and reduced demineralization, whereas CFR showed limited differences compared with the conventional GIC.