The authors recommend a simple algorithm for the restriction-endonuclease analysis of genetic material of microorganisms present on mucous membrane of oral cavity. The method provides a significantly more precise species identification of bacteria associated with diseases of periodontium. The method is based on analysis of the part of the gene for 16S rRNA and its use is therefore universal and may be combined with identification of other clinically important organisms of oral cavity, e.g. viridans streptococci. The requirements of the method for equipment and cost are not high, as it uses a limited number of restriction enzymes. Although the method is comparable with classical biochemical methods as far as the cost is concerned, it represents an improvement due to unequivocal classification of the microorganisms, which is a general feature of molecular-genetic techniques.

        Key words: microorganisms of oral cavity – periodontal pathogens – DNA techniques