Introduction: Dental caries is the most common dental disease, caused by demineralisation of enamel. The bacteria Streptococcus mutans is the main cause od dental caries, because it produces acid by metabolising carbohydrates, which disrupts the pH of the oral cavity. Sucrose is considered to be the most cariogenic carbohydrate, causing biofilm porosity and promoting bacterial adhesion. The edges of dental restorations are ideal sites for bacterial adhesion, which can lead to diseases such as secondary caries, parodontitis and periimplantitis. Purpose: The purpose of the bachelor's thesis is to determine how different concentrations of sucrose affect the adhesion of S. mutans on Co-Cr and composite. The aim is to determine at which sucrose concentration, the adhesion is the highest. Methods: In the practical part of the bachelor's thesis, samples of Co-Cr and composite surfaces were prepared. The physical properties of these surfaces were measured. We measured the roughness, hydrophobicity and zeta potential. We prepared a pure cuture of S. mutans and media with different concentrations of sucrose in the microbiology laboratory. Adhesion was measured by SEM method and crystal violet staining. In the dental laboratory, we made a crown with a Co-Cr framework anf a composite veneer. Results: Higher roughness was measured for the composite with ^^ of (0.32 ± 0.06) μm and lower roughness for Co-Cr with ^^ of (0.21 ± 0.03) μm. The superficial limiting angle of the Co-Cr surface is (76,66 ± 2,39) ° and that of the composite is (74,16 ± 2,95)°, indicating that both surfaces are hydrophilic. The average value of the zeta potential for the Co-Cr surface is (-52,428 ± 0,322) mV and for the composite is (-25,912 ± 10,09) mV. Both surfaces are negatively charged. In the SEM method, the highest level of adhesion of S. mutans to Co-Cr and the composite was determined at 5% sucrose and the lowest at 0% sucrose. In the crystal violet dye method, the highest level of adhesion of S. mutans to Co-Cr and the composite was determined at 2,5 % and the lowest at 0 %. Discussion and conclusion: The results of our study show that sucrose has an effect on the adhesion of S. mutans to the surface of Co-Cr and the composite. The adhesion increased with increasing sucrose content. Comparing the individual sucrose ratios, we find that the composite has a higher degree of S. mutans adhesion than Co-Cr. The roughness, hydrophobicity and zeta potential affect the adhesion of S. mutans.
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