Dental caries is a significant health problem, particularly in children in developing countries like Syria. The disease arises from plaque accumulation and the subsequent production of acid by cariogenic bacteria, primarily *Streptococcus mutans*. While oral hygiene practices are crucial, additional measures like antibacterial and remineralizing agents are necessary for high-risk individuals. Bioactive glass (BAG) toothpastes, such as BioMin and NovaMin, offer remineralization properties due to their calcium and phosphate content. BioMin F, containing fluoride, forms fluorapatite, releasing fluoride for up to 12 hours. NovaMin, containing calcium sodium phospho-silicate, releases calcium, sodium, and phosphate ions, increasing pH and facilitating remineralization. Previous studies have focused on the remineralization effects of these toothpastes; however, their antimicrobial efficacy against *Streptococcus mutans* remains unexplored. This study aimed to compare the antibacterial effects of BioMin F, NovaMin, and Signal toothpastes against *Streptococcus mutans* isolated from children with severe early childhood caries (SECC).

The literature highlights the complex mechanism of dental caries, involving plaque accumulation, carbohydrate fermentation, acid production, and enamel destruction. *Streptococcus mutans*, with its acidogenic properties and extracellular matrix formation, is a key pathogen. Daily oral hygiene is effective in caries control, but for high-risk individuals, combined antibacterial and remineralizing agents are beneficial. Bioactive glasses (BAGs) are increasingly used in oral health due to their remineralization potential and ability to raise the oral pH. Various commercial BAG products, including BioMin and NovaMin, have shown efficacy in enamel remineralization and reducing post-bleaching sensitivity. However, limited research exists on their direct antimicrobial effects against *Streptococcus mutans*.

This *in vitro* study involved isolating *Streptococcus mutans* from dental plaque samples collected from 10 children (4 males, 6 females) aged 2-6 years with SECC. Ethical approval was obtained. Mitis Salivarius Bacitracin Agar was used for isolation. The isolated *Streptococcus mutans* was confirmed using catalase and Gram staining, and polymerase chain reaction (PCR) tests. The agar diffusion method was employed to assess the antibacterial effects of BioMin F, NovaMin, and Signal toothpastes. A Mueller-Hinton medium was used, and 100 µl of a standardized bacterial suspension (0.5 McFarland standard) was spread on each petri dish. Three wells were created per dish, one for each toothpaste. After 24 hours of incubation at 37°C in a 15% CO2 incubator, the inhibition zone diameters were measured using a digital caliper. Data analysis was performed using SPSS 17, with One-way ANOVA and Bonferroni tests for intergroup and pairwise comparisons, respectively. A p-value < 0.05 indicated statistical significance.

The study revealed significant differences in the mean inhibition zone diameters among the three toothpastes. BioMin F demonstrated the largest mean inhibition zone (2.67 mm ± 0.42), significantly larger than NovaMin (0.39 mm ± 0.42) and Signal (2.19 mm ± 0.26) (p < 0.001 for each pairwise comparison). Signal showed a significantly larger inhibition zone than NovaMin (p < 0.001).

The results refute the null hypothesis that all toothpastes would inhibit *Streptococcus mutans* similarly. BioMin F's superior efficacy is likely attributed to the sustained release of fluoride from fluorohydroxyapatite, which remains active for up to 12 hours in neutral environments, unlike the sodium fluoride in NovaMin and Signal, which loses its effectiveness within 90-120 minutes. The crystalline structure of calcium and phosphate in BioMin F might also contribute to its inhibitory effect on *Streptococcus mutans* biofilm formation. The presence of Sodium Lauryl Sulfate in Signal might also contribute to its relatively better performance compared to NovaMin. These findings align with other studies showing the anti-cariogenic effects of bioactive glasses containing calcium, phosphate, fluoride, and strontium ions. However, differences in methodology and incubation periods may explain some discrepancies between this study and previous research.

BioMin F exhibited significantly superior antibacterial activity against *Streptococcus mutans* compared to NovaMin and Signal toothpastes. This *in vitro* study suggests that BioMin F holds promise as a preventive measure against dental caries. Future research should investigate its efficacy against other cariogenic bacteria and in more acidic environments, mirroring oral conditions more accurately. Furthermore, testing the efficacy of the toothpastes against individual *Streptococcus mutans* strains isolated from each child would strengthen the study's findings.

The study's limitations include focusing solely on *Streptococcus mutans*, neglecting other cariogenic bacteria, and using a Mueller-Hinton medium with moderate acidity, potentially underrepresenting the effect of fluoride in more acidic conditions. The study could be improved by examining the efficacy against a wider range of bacteria and in more clinically relevant media. Furthermore, a direct comparison of the isolated bacterial strains from each child and their response to the respective toothpastes would further refine the results.