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Streptococcus mutans (S. mutans) antisense vicK RNA (ASvicK) is a non-coding RNA that regulates cariogenic virulence and metabolic activity. Dimethylaminohexadecyl methacrylate (DMAHDM), a quaternary ammonium methacrylate used in dental materials, has strong antibacterial activity. This study examined the effects of S. mutans ASvicK on DMAHDM susceptibility and their combined impact on inhibiting S. mutans biofilm formation and protecting enamel hardness. The parent S. mutans UA159 and ASvicK overexpressing S. mutans (ASvicK) were tested. The minimum inhibitory concentration (MIC) and minimum bactericidal concentrations for planktonic bacteria (MBC-P) and biofilms (MBC-B) were measured. As the ASvicK MBC-B was 175 µg/mL, live/dead staining, metabolic activity (MTT), colony-forming units (CFUs), biofilm biomass, polysaccharide, and lactic acid production were investigated at 175 µg/mL and 87.5 µg/mL. The MIC, MBC-P, and MBC-B values for DMAHDM for the ASvicK strain were half those of the UA159 strain. In addition, combining S. mutans ASvicK with DMAHDM resulted in a significant 4-log CFU reduction (p < 0.05), with notable decreases in polysaccharide levels and lactic acid production. In the in vitro cariogenic model, the combination achieved the highest enamel hardness at 67.1% of sound enamel, while UA159 without DMAHDM had the lowest at 16.4% (p < 0.05). Thus, S. mutans ASvicK enhanced DMAHDM susceptibility, and their combination effectively inhibited biofilm formation and minimized enamel demineralization. The S. mutans ASvicK + DMAHDM combination shows great potential for anti-caries dental applications.

RESUMEN

PURPOSE: To investigate antifungal and mechanical properties after the impregnation of Dimethyl Amino-ethyl Hexa-decyl Di-methacrylate (DMAHDM) alone or in combination with Nystatin in polymethylmethacrylate. METHODOLOGY: The control group was fabricated by mixing powder and liquid of PMMA at the ratio of 2.5:1 g/mL. The DMAHDM was added to PMMA liquid and were mixed with PMMA powder. The Nystatin (500,000 International Units (IU)) was mixed with PMMA powder, whereby the composite powder was mixed with the DMAHDM-based liquid. The prepared specimens were tested for fungal adhesion testing (at days 1 and 30), impact strength and flexural strength. Oneway ANOVA post-hoc Tukey's test were used for statistical analysis. RESULTS: Statistical analysis for the adhesion assay revealed that the antifungal activities of unaged and aged specimens in experimental groups were statistically significant as compared to control group A. The groups containing DMAHDM with Nystatin have shown statistically reduced flexural strength. The impact strength test revealed that groups containing 20% DMAHDM alone and DMAHDM with Nystatin showed statistically reduced impact strength compared to the control group. CONCLUSION: Antifungal activities of experimental PMMA resin was increased. The addition of DMAHDM alone in PMMA resin has no deleterious effects on impact and flexural strength, however, at higher concentration values were reduced.

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OBJECTIVE: The bonding interface of dental filling therapy is the weak point in resisting secondary caries. Adhesives containing nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) have been demonstrated in vitro to prevent bacteria from producing acid and to promote tooth remineralization. The present study aimed to evaluate the efficacy of adhesive with NACP and DMAHDM to prevent secondary caries in vivo. MATERIALS AND METHODS: Artificial cavities were created on the first molar on both sides of the maxillary in a rat model. One side was treated with adhesive containing NACP + DMAHDM, while on the other side, a commercial adhesive served as control. After 24 days of cariogenic feeding, the degree of secondary caries was evaluated by micro-CT and a modified Keyes scoring method. Quantitative real-time PCR (qPCR) and colony-forming unit (CFU) counts were used to evaluate the antibacterial efficacy of the materials. Biocompatibility was also investigated. RESULTS: In the rat model, the adhesive with NACP + DMAHDM showed excellent biocompatibility and effectively decreased the amount of bacteria. The experimental group demonstrated excellent remineralization effectiveness, with a lower modified Keyes score and mineral loss of 34.16 ± 2.13 vol% µm, compared with 77.44 ± 7.22 vol% µm in the control group, according to micro-CT (P < 0.05), showing excellent capacity to inhibit secondary caries. CONCLUSIONS: The NACP-DMAHDM-containing adhesive exhibited good performance in preventing secondary caries in vivo. CLINICAL RELEVANCE: Adhesives containing NACP and DMAHDM have great potential for use in clinical dentistry to prevent secondary caries by inhibiting bacterial growth and promoting remineralization.

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