Periopathogenic bacteria in persistent periapical lesions: an in vivo prospective study

The aim of this in vivo prospective study was to detect the presence of periopathogenic bacteria in persistent periapical lesions and to compare the reliability of two different methods: anaerobic culture and the DNA hybridization technique.

Samples were obtained from 24 patients with persistent periapical lesions referred for surgical endodontic treatment. A sterile paper point was inserted into the periapical lesion for 10 seconds. The point was stored in sterile transfer tubes and analyzed by DNA hybridization. Tissue samples were transported in transfer medium and analyzed further using anaerobic culture.

At least one periodontal pathogenic bacterium was found in seven of 24 cases. Bacterial species present were Treponema denticola (three cases), Porphyromonas gingivalis (three cases), Tannerella forsythensis (four cases), Prevotella intermedia (one case), and Actinobacillus actinomycetemcomitans (three cases). No particular signs or symptoms were associated with the presence of these bacterial species. Anaerobic culture failed to identify any of the periopathogenic bacteria.

Periodontal pathogenic bacterial DNA can be detected in persistent periapical lesions. Anaerobic cultures failed to detect the periodontal pathogenic bacteria in positive hybridization assays, suggesting that standard culture methods lack sensitivity or that hybridization assays are flawed with low specificity. The clinical significance of the presence of bacterial DNA in persistent periapical lesions remains to be determined.