Extraradicular infection: a methodological study.

Whether bacteria live or die in periapical lesions of endodontic origin is debated. Sampling of periapical bacteria is difficult due to possible contamination from the indigenous microflora. The aim of this study was to examine whether bacteria were present in periapical lesions of asymptomatic teeth before sampling or were transferred there during sampling. Thirty patients with root-filled teeth and periapical radiolucencies were divided into two groups, each containing 15 patients. In Group 1, a marginal incision was made to explore the periapical lesion. In Group 2, a submarginal incision was made. Before incision, the gingiva and mucosa were washed with 0.2% chlorhexidine gluconate. Bacterial samples were taken from the mucosa before reflecting the flap, and from the alveolar bone and the periapical lesion immediately after. All samples were cultured anaerobically on all-purpose and selective media. In Group 1, 12 of the 15 patients (80%) yielded bacteria from their mucosal samples despite the chlorhexidine wash. Bacterial growth was observed in all samples (100%) from the alveolar bone while the periapical lesions gave bacterial growth in 11 of 15 cases (73%). In Group 2, bacteria were cultured from the mucosa in 11 of 15 (73%) patients. Three samples (20%) from the alveolar bone and 10 from the periapical lesions (67%) gave positive growth. The predominant cultivable bacteria were anaerobic. Phenotypic profiling, performed with the data-based API bioMérieux system, indicated that the sampling technique used prevented mucosal bacteria from reaching the exposed bone and the periapical lesions. Profiling also indicated that following marginal incision, bacteria from the periodontal pocket might have reached the underlying tissues by surgeon-released bacteremia or direct translocation. Most organisms detected in the periapical lesions were clearly different from the bacteria present at neighboring sites and appeared to have been there before sampling.