Sadia Ambreen Niazi
Published: 2011
Total Pages: 734
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Refractory root canal infections are polymicrobial and their prevention and treatment present as a major challenge in clinical practice. The aim of this study was to investigate the predominant cultivable microflora of of teeth associated with refractory lesions and to develop a reproducible in vitro stressed multispecies model biofilm on extracted human teeth in order to determine the biofilm killing and disrupting efficacy of various chemomechanical procedures. The characteristics of Propionibacterium acnes and Staphylococcus epidermidis isolates from root canals associated with refractory lesions and peri-oral skin samples from the same subjects were also investigated. The predominant cultivable microbiota from 20 refractory endodontic lesions (9 with abscesses and 11 without abscesses) were determined, and P. acnes and S. epidermidis were among the most predominant organisms. The number of species identified from lesions with abscesses was significantly greater than the number from lesions without abscesses. Comparison of peri-oral isolates using repetitive extragenic palindromic PCR of the same species from the same subject demonstrated that the endodontic and skin populations were significantly different. The P. acnes isolates were typed on the basis of recA gene sequence comparison and types IA, IB, II, and III were identified among 125 isolates examined. The types IA and IB were primarily isolated from skin, while type II and III were significantly more likely to be isolated from endodontic lesions. Moreover, the robustness of the recA phylotypes was not strong by comparing the partial gene sequences of six putative virulence determinants, PAmce, PAp60, PA-25957, PA-5541, PA-21293, and PA-4687. The resulting neighbour-joining trees were incongruent, and significant evidence of recombination was demonstrated, with significant phylogenetic heterogeneity being apparent within the clusters.