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A low-shrinkage-stress (LSS), antibacterial and remineralizing nanocomposite was recently developed; however, validation of its long-term antibacterial potency in modulating human salivary-derived biofilm is an unmet need. This study aimed to evaluate the antibacterial effect of the bioactive LSS composite before and after aging in acidic solution for 90 days using a multi-species biofilm model, and to evaluate its cytotoxicity. The LSS composite consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE), 3% dimethylaminohexadecyl methacrylate (DMAHDM) and 20% nanoparticles of amorphous calcium phosphate (NACP). Biofilm colony-forming units (CFU), lactic acid production, and confocal laser scanning microscopy (3D biofilm) were evaluated before and after three months of aging. Cytotoxicity was assessed against human gingival fibroblasts (HGF). The new LSS composite presented the lowest biofilm CFU, lactic acid and biofilm biomass, compared to controls (n = 6, p < 0.05). Importantly, the new composite exhibited no significant difference in antibacterial performance before and after 90-day-aging, demonstrating long-term antibacterial activity (p > 0.1). The LSS antibacterial and remineralizing composite presented a low cell viability at original extract that has increased with further dilutions. In conclusion, this study spotlighted that the new bioactive composite not only had a low shrinkage stress, but also down-regulated the growth of oral biofilms, reduced acid production, maintained antibacterial activity after the 90-day-aging, and did not compromise the cytocompatibility. [ABSTRACT FROM AUTHOR]

Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3. This novel approach is promising co-adjuvant route for prevention of dental caries dissemination in millions of patients under orthodontic treatment. [ABSTRACT FROM PUBLISHER]