[Critical assessment of microbiological diagnostics in periodontal diseases with special focus on Porphyromonas gingivalis].

Periodontitis is caused by an opportunistic infection with pathogenic microorganisms of the oral biofilm. In this paper, we discuss the usefulness of microbial diagnostics with respect to the differential diagnosis or the treatment approaches of periodontal diseases. Several diagnostic techniques, based on morphological, enzymatic, cultural, genetic or antigenetic properties have been established to analyze the microbial flora. Among the bacterial species some virulent genotypes of P. gingivalis play an important role in the etiology of periodontitis. Expression of fimbriae or different proteases have been identified as potential virulence factors of this gram negative anaerobic rod. To date a characterization of virulence of specific strains or a correlation between expression of different virulence factors and distinct periodontal conditions, however, is missing. Therefore, the importance of a routine identification of P. gingivalis still needs further evaluation.