Streptococcus mutans is one of the important bacteria that forms dental biofilm and cause dental caries. Virulence genes in S. mutans can be classified into the genes involved in bacterial adhesion, extracellular polysaccharide formation, biofilm formation, sugar uptake and metabolism, acid tolerance, and regulation. The genes involved in bacterial adhesion are gbps (gbpA, gbpB, and gbpC) and spaP. The gbp genes encode glucan-binding protein (GBP) A, GBP B, and GBP C. The spaP gene encodes cell surface antigen, SpaP. The genes involved in extracellular polysaccharide formation are gtfs (gtfB , gtfC , and gtfD ) and ftf , which encode glycosyltransferase (GTF) B, GTF C, and GTF D and fructosyltransferase, respectively. The genes involved in biofilm formation are smu630, relA , and comDE. The smu630 gene is important for biofilm formation. The relA and comDE genes contribute to quorumsensing and biofilm formation. The genes involved in sugar uptake and metabolism are eno, ldh , and relA . The eno gene encodes bacterial enolase, which catalyzes the formation of phosphoenolpyruvate. The ldh gene encodes lactic acid dehydrogenase. The relA gene contributes to the regulation of the glucose phosphotransferase system. The genes related to acid tolerance are atpD, aguD, brpA, and relA . The atpD gene encodes F1F0-ATPase, a proton pump that discharges H+ from within the bacterium to the outside. The aguD gene encodes agmatine deiminase system and produces alkali to overcome acid stress. The genes involved in regulation are vicR, brpA, and relA .

The objective of this study was to examine the expression pattern of Kelch-like ECH-associated protein 1 (Keap1) in the maxillary 2nd molar germs of rats. We used the maxillary 2nd molar germs in rats’ pup at postnatal day 3 (bell stage), 6 (crown formation stage) and 9 (root formation stage). The investigation on mRNA and protein levels were done using reverse transcription - polymerase chain reaction and western blot. Localization of Keap 1 in the maxillary 2nd molar germs were revealed through immunofluorescence staining. Keap1 from the maxillary 2nd molar germs were mostly manifested on postnatal day 3 and dramatically decreased on postnatal day 6 and 9 at mRNA and protein levels, while amelogenin and ameloblastin increased during the development of maxillary 2nd molar germs. During immunofluorescence analysis, the strong immunoreactivity against Keap1 was detected in the apical side of ameloblasts at the presecretory and secretory stages. However, Keap1 expression was hardly observed in the ameloblasts at the maturation stage. These results shows that Keap1 is strongly expressed in the presecretory and secretory ameloblasts of amelogenesis, and suggest that Keap1 may be a crucial molecule for the regulatory mechanisms tasked with the formation of enamel layer.

It is noted that Streptococcus mutans (S. mutans) triggers dental caries establishment by two major factors: the synthesis of organic acids, which demineralize dental enamel, and the synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Therefore, it is noted that the development of a more effective, substantial and safe preventive agent that works against dental caries and periodontal disease is required at this time. For this reason, the present study was designed to investigate the effect of croton seed ethanol extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of S. mutans. In this case, the ethanol extract of croton seed showed concentration dependent inhibitory activity against the growth, acid production and adhesion of S. mutans. Especially, it is important to note that it has produced significant inhibition at the concentration of 0.1 and 0.2 mg/ml as compared to the control group. Moreover, these results suggest that the application of croton seed extract may be considered to be a useful method for the prevention of dental caries.

Dental caries is the most common chronic disease in the dental field. Streptococcus mutans (S. mutans) is the most important bacteria in the formation of dental plaque and dental caries. In a previous study, we confirmed that the essential oil of Chrysanthemum boreale has antibacterial activity against S. mutans. Alpha-pinene is one of the major chemical components of Chrysanthemum boreale essential oil. In the present study, we investigated the inhibitory effects of ɑ-pinene on cariogenic properties such as growth, acid production, biofilm formation, and bactericidal activity on S. mutans. Alpha-pinene at a concentration range of 0.25-0.5 mg/mL significantly inhibited the growth of S. mutans and acid production of S. mutans. Biofilm formation was significantly inhibited at > 0.0625 mg/mL ɑ-pinene, similar to the data from scanning electronic microscopy. Under confocal laser scanning microscopy, the bacterial viability was decreased by ɑ-pinene in a dose-dependent manner. These results suggested that ɑ-pinene may be a useful agent for inhibiting the cariogenic properties of S. mutans.

Streptococcus mutans (S. mutans) is one of the most important bacteria in the formation of dental plaque and dental caries. S. mutans adheres to an acquired pellicle formed on the tooth surface, and aggregates with many oral bacteria. It initiates plaque formation by synthesizing glucan from sucrose, which is catalyzed by glucosyltransferases. Propolis is a resinous mixture produced by honeybees, by mixing saliva and beeswax with secretions gathered from wood sap and flower pollen. Bees prevent pathogenic invasions by coating the propolis to the outer and inner surface of the honeycomb. Propolis has traditionally been used for the treatment of allergic rhinitis, asthma and dermatitis. We investigated the inhibitory effects of propolis ethanol extract on biofilm formation and gene expression of S. mutans. The biofilm formation of S. mutans was determined by scanning electron microscopy (SEM) and safranin staining. We observed that the extract of propolis had an inhibitory effect on the formation of S. mutans biofilms at concentrations higher than 0.2 mg/ml. Real-time PCR analysis showed that the gene expression of biofilm formation, such as gbpB, spaP, brpA, relA and vicR of S. mutans, was significantly decreased in a dose dependent manner. The ethanol extract of propolis showed concentration dependent growth inhibition of S. mutans, and significant inhibition of acid production at concentrations of 0.025, 0.05, 0.1 and 0.2 mg/ml, compared to the control group. These results suggest that the ethanol extract of propolis inhibits gene expression related to biofilm formation in S. mutans.

Retinoic acid plays an important role in the regulation of cell growth and differentiation. In our present study, we evaluated the effects of all-trans retinoic acid (RA) on cell proliferation and on the cell cycle regulation of human gingival fibroblasts (HGFs). Cell proliferation was assessed using the MTT assay. Cell cycle analysis was performed by flow cytometry, and cell cycle regulatory proteins were determined by western blot. Cell proliferation was increased in the presence of a 0.1 nM to 1μM RA dose range, and maximal growth stimulation was observed in cells exposed to 1 nM of RA. Exposure of HGFs to 1 nM of RA resulted in an augmented cell cycle progression. To elucidate the molecular mechanisms underlying cell cycle regulation by RA, we measured the intracellular levels of major cell cycle regulatory proteins. The levels of cyclin E and cyclin-dependent kinase (CDK) 2 were found to be increased in HGFs following 1 nM of RA treatment. However, the levels of cyclin D, CDK 4, and CDK 6 were unchanged under these conditions. Also after exposure to 1 nM of RA, the protein levels of p21 WAF1/CIP1 and p16 INK4A were decreased in HGFs compared with the control group, but the levels of p53 and pRb were similar between treated and untreated cells. These results suggest that RA increases cell proliferation and cell cycle progression in HGFs via increased cellular levels of cyclin E and CDK 2, and decreased cellular levels of p21 WAF1/CIP1 and p16 INK4A.

In our present study, we investigated the effects of continentalic acid on Streptococcus mutans (S. mutans) biofilm. Methanol extract of Aralia continentalis (A. continentalis) was suspended in water and sequentially partitioned with CHCl3, ethyl acetate (EtOAc), and n-butanol (n-BuOH). The CHCl3 fraction showed the highest activity and an antibacterial compound against S. mutans was isolated from this preparation through various chromatography methods by bioassay guided fractionation. MS, 1H - NMR and 13C-NMR analysis showed that the active principle was continentalic acid which was confirmed to show significant inhibitory effects against S. mutans biofilm. These results may provide some scientific rationale for the traditional use these extracts for the treatment of dental diseases.