2.2. Growth Curve of S. mutans

One milliliter of bacterial suspension (in cell concentration 10⁹ CFU ml^−L) from overnight culture was taken and diluted to a proximal cell concentration of 10⁷ CFU ml^−L in a fresh nutrient broth (BHI broth) and cultivated for 5, 10, 15, 20, and 24 h at 37 °C. The growth of bacteria was measured with pour plate counts on a BHI agar (the standard was ISO 4833-1:2013—the microbiology of the food chain: horizontal method for the enumeration of microorganisms—Part 1: colony count at 30 ℃ by the pour plate technique). Eventually, the inhibitory effect of the tested materials on bacterial growth was tested in parallel aliquots with the presence of tested materials (plates of 100 mm²).