Journal of Dental Medicine

Background and Aims: Dental caries is the most common infectious diseases. Among the oral bacteria, Streptococcus mutans and Streptococcus sobrinus are considered as the main causes of tooth decay. The aim of this study was to evaluate the production of hyperimmune bovine colostrum containing specific antibodies against cariogenic bacteria and its antimicrobial effects on the growth and adhesion of Streptococcus mutans and Streptococcus sobrinus in the laboratory.

Materials and Methods: In this experimental study, three pregnant bovine immunized with killed antigens of strains of Streptococcus mutans, Streptococcus mutans with Streptococcus Sobrinus and Streptococcus sobrinus through intramuscular injections. After delivery, The colostrum samples were collected, and the changes of anti-streptococci antibodies titers in colostrum and serum were determined by agglutination. Also,their antimicrobial effects against the growth and adhesion of oral streptococci were surveyed by the microtiter plate method. Data were analysed by One-Wey ANOVA in SPSS software.

Results: The results showed that in hyperimmunized bovine , the antibodies titers against injected bacteria were from 1.1000 to 1.3000 in sera samples and from 1.320 to 1.1280 in whey of colostrum samples. Colostrum of hyperimmune cows reduced the attachment of Streptococcus mutans and Streptococcus Sobrinus about 69 and 43 percents, respectively and also, the low dilutions of it reduced bacterial growth.

Conclusion:  According to the antibacterial effect immune colostrum on two strains of cariogenic bacteria in vitro, It appears that this material could be useful in the prevention and control of dental caries.

Background and Aims: Dental caries is an infectious disease transmitted by multiple factors in the mouth and one of the most common chronic diseases in the world that requires a lot of treatment expenses. The aim of this study was to evaluate the effect of fluoride 0.2% and Fuchs mouthwash (a combination of xylitol and fluoride 920 ppm) against two bacterial growths (Streptococcus mutans and Lactobacillus acidophilus).

Materials and Methods: In this in vitro study, first the well diffusion method and then MIC method (minimum inhibitory concentration) were used. Data were analyzed with Excell (2016).

Results: The results of the MIC method showed inhibitory effect of both mouthwashes in pure concentration (128 μg/ml). However, fluoride was effective in concentration higher than 32 μg/ml for Streptococcus mutans and higher than 2 μg/ml for lactobacillus acidophilus. Fuchs was effective for both bacteria at concentration higher than 64 μg/ml and in lower concentration it was ineffective. The results of the well diffusion test showed the inhibition of fluoride mouthwash in pure concentration on the Streptococcus mutans was (17 mm) and on the lactobacillus acidophilus 24 mm was obtained. In Fuchs mouthwash was zero and it represented effectiveness of fluoride on bacteria and ineffectiveness of Fuchs.

Conclusion: The fluoride mouthrinse in different concentrations, because of having a good inhibitory effect in both methods on Streptococcus mutans and Lactobacillus acidophilus was more effective compared with that of Fuchs mouthrinse.

Background and Aims: Nowadays, new techniques are used to control dental caries that have the ability to kill cariogenic bacteria. Recently, the addition of antibiotics to glass ionomers has been proposed to reduce the overall number of saliva bacteria. The aim of this study was to compare the antimicrobial effect and compressive strength of resin- modified glass ionomer (RMGI) containing different antibiotics on Streptococcus mutans.
Materials and Methods: A total of 120 specimens were prepared in 3 groups (n=40) including RMGI containing doxycycline with a concentration of 1.5%, RMGI containing a combination of ciprofloxacin, metronidazole and minocycline with a concentration of 1.5%, and RMGI without antibiotics as control group. To measure the antibacterial effect, the disk diffusion method and counting of Streptococcus mutans bacterial colonies were used and then the compressive strength test was performed. Data were collected into SPSS25 and analyzed by ANOVA and Kruskal-Wallis tests and the significance level was considered α=0.05.
Results: The mean number of bacterial colonies in the RMGI group containing doxycycline in all three time intervals 1, 24 hours and 7 days was significantly lower than the specimens in the RMGI group containing the triple antibiotic (P<0.001). The mean compressive strength of the two experimental groups was lower than the control group but was not statistically significant (P=0.326).
Conclusion: The addition of antibiotics at a concentration of 1.5% to RMGI resulted in a favorable antibacterial property with no significantly change in the compressive strength.

Background and Aims: To prevent dental caries, investigations have focused on finding new antibacterial and anti-biofilm agents without the drawbacks of the currently used synthetic agents. This study aimed to assess the effect of methanolic extract of Zingiber officinale (Z. officinale) on expression of virulence genes of Streptococcus mutans (S. mutans) using real-time polymerase chain reaction (PCR).
Materials and Methods: In this in vitro study, which was conducted in the year 1402, at the Microbiology Department of the Faculty of Medicine and the Faculty of Dentistry at Shahid Beheshti University of Medical Sciences, the methanolic extract of Z. officinale was obtained by the maceration technique. 10 clinical isolates of S. mutans were obtained from the patients with dental infection. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract against S. mutans were determined by the microtiter plate technique. The effect of extract on the expression of relA, comDE, brpA, gtfC, and spaP virulence genes by the clinical isolates was evaluated by the real-time polymerase chain reaction (PCR) technique. Data were analyzed by the Wilcoxon and Mann-Whitney tests (alpha=0.05).
Results: The mean MIC and MBC of the methanolic extract of Z. officinale against S. mutans were 32±11.8 and 64±26.12 mg/mL, respectively. The extract caused down-regulation of relA, comDE, brpA, and gtfC by 50%, 40%, 70%, and 70%, respectively. It also caused 4 times reduction in expression of spaP gene.
Conclusion: The methanolic extract of Z. officinale caused significant down-regulation of gtfC, brpA, relA, comDE, and spaP genes, indicating its optimal efficacy to control the virulence of S. mutans.