The authors proposed an algorithm for the analysis of genetic material of oral streptococci, giving significantly more precision to generic identification of bacteria associated with destruction of hard dental tissues. The method based on analysis of parts of the gene for 16S rRNA was verified in laboratory for generic identification of 87 isolates of oral streptococci and correctness of the results was confirmed by the “absolute” method, i.e. by DNA sequencing of the analyzed segment. The proposed procedure can be used in general and the analysis can be extended to other clinically important microorganisms of oral cavity, e.g. bacteria of mucosa associated with the periodontium diseases. The proposed financially modest method makes an unequivocal generic identification possible even for genera, which are difficult to differentiate by biochemical methods. For example it safely differentiates streptococci within the S. mutans group.

        Key words: oral streptococci - S. mutans - S. sobrinus - DNA techniques