•Purpose: to recover and identify the flora of refractory periapical endodontic lesions, i.e. lesions of teeth with apical periodontitis
•36 patients receiving treatment within a period of 6 yr. Dx: asymptomatic apical periodontitis +\-fistula.
•standard RCT: instrumentation in first visit &a 2-3 weeks with calcium hydroxide.
•when apical exudation persisted or fistulas did not close , long-term CaOH2 therapy (3\6 months).
•systemic, antibiotic treatment. If not responding, Dx: refractory apical periodontitis è (apicoectomy)
•Bacterial samples were taken from PA lesion after reflecting the flap , PA lesion was removed by using sterile curettes
•Microbiological Assessment : cultivation, scanning and transmission electron microscopy
Most highlighted Results:
1. Thirty-five of the 36 periapical lesions yielded microbial growth.
2.(51%) were anaerobic. 79.5% were Gram-positive
3.75% of the refractory lesions contained Staphylococcus, Bacillus, Pseudomonas, Stenotrophomonas, Sphingomonas, Enterococcus, Enterobacter, or Candida species.
4.All the periapical samples from the eight patients taken antibiotics before surgery yielded microbial growth.
5.There was no statistical difference in the occurrence of microbial species between patients with the diagnosis of asymptomatic apical periodontitis and those with the diagnosis of apical periodontitis with fistula.
6.25% of the 36 patients, sulfur granules were recovered, Actinomyces israelii, A. viscosus, A. naeslundii, and A. meyeri were identified
7.In TEM of the sulfur granules, bacteria with a Gram-positive and Gram-negative cell wall were observed.
8.By SEM, it was seen that the sulfur granules were tightly packed with microorganisms
A wide variety of microorganisms remained in refractory PA endodontic lesions after long- term, root-canal treatment with calcium hydroxide and systemic- antibiotic treatment.