Browsing by Author "Gregory, R. L."

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    Growth and viability of Streptococcus mutans in sucrose with different concentrations of Stevia rebaudiana Bertoni
    (Springer, 2020) Escobar, E.; Piedrahita, M.; Gregory, R. L.; Biomedical Sciences and Comprehensive Care, School of Dentistry
    Objective To evaluate total absorbance, planktonic growth, biofilm formation, viability, metabolic activity, and pH of Streptococcus mutans UA159 cultures when different dilutions of Stevia rebaudiana Bertoni were applied and to determine the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of Stevia on S. mutans. Materials and methods The effects of different dilutions of Stevia (0–400 mg/ml) on S. mutans total growth, planktonic growth, biofilm formation, viability, metabolic activity, and pH during a 72-h growth period were evaluated in this in vitro study. A stock solution was prepared by mixing 10 ml of tryptic soy broth (TSB) supplemented with 1% sucrose (TSBS) and 4 g of Stevia. Results S. mutans total growth and biofilm formation decreased with reduced concentrations of Stevia. Furthermore, the MIC was 25 mg/ml and the MBIC was 6.25 mg/ml. Complete eradication of S. mutans was not observed with any of the Stevia concentrations. Planktonic growth of S. mutans was not repressed by high concentrations of Stevia and most of the Stevia concentrations generated an increased pH. Conclusion Because Stevia reduces biofilm and acid production, Stevia can be considered a non-cariogenic sweetener. Clinical relevance This study confirms the anticariogenic effect of Stevia, like it has been previously reported, but more studies on the most effective concentration are needed, and in the present study, the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) was determined in the presence of sucrose. Additionally, this is the first study to evaluate the effect of Stevia on S. mutans metabolic activity.
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    Novel bioactive tetracycline-containing electrospun polymer fibers as a potential antibacterial dental implant coating
    (SpringerLink, 2017-07) Shahi, R. G.; Albuquerque, M. T. P.; Münchow, E. A.; Blanchard, S. B.; Gregory, R. L.; Bottino, M. C.; Biomedical Sciences and Comprehensive Care, School of Dentistry
    The purpose of this investigation was to determine the ability of tetracycline-containing fibers to inhibit biofilm formation of peri-implantitis-associated pathogens [i.e., Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi), and Aggregatibacter actinomycetemcomitans (Aa)]. Tetracycline hydrochloride (TCH) was added to a poly(DL-lactide) [PLA], poly(ε-caprolactone) [PCL], and gelatin [GEL] polymer blend solution at distinct concentrations to obtain the following fibers: PLA:PCL/GEL (TCH-free, control), PLA:PCL/GEL + 5 % TCH, PLA:PCL/GEL + 10 % TCH, and PLA:PCL/GEL + 25 % TCH. The inhibitory effect of TCH-containing fibers on biofilm formation was assessed by colony-forming units (CFU/mL). Qualitative analysis of biofilm inhibition was done via scanning electron microscopy (SEM). Statistical significance was reported at p < 0.05. Complete inhibition of biofilm formation on the fibers was observed in groups containing TCH at 10 and 25 wt%. Fibers containing TCH at 5 wt% demonstrated complete inhibition of Aa biofilm. Even though a marked reduction in CFU/mL was observed with an increase in TCH concentration, Pi proved to be the most resilient microorganism. SEM images revealed the absence of or a notable decrease in bacterial biofilm on the TCH-containing nanofibers. Collectively, our data suggest that tetracycline-containing fibers hold great potential as an antibacterial dental implant coating.