Identification of Culturable and Nonculturable Microorganisms,Lipopolysaccharides, and Lipoteichoic Acids From Root Canals of Teeth With Endodontic Failure

AimTo elucidate the presence of apical periodontitis in the root canal of teeth with secondary/persistent infection, including composition of microbiota, levels of endotoxins and lipoteichoic acid (LTA), and clinical implications of these findings.MethodSamples were collected from root canals of 50 patients who needed endodontic retreatment and had radiographic evidence of apical periodontitis. Microorganisms were identified by using the culture technique and biochemical tests. Nested–polymerase chain reaction (nested-PCR) was used to identify 17 species of specific bacteria. Lipopolysaccharides (LPS) and LTAs were quantified by using, respectively, limulus amebocyte lysate and enzyme-linked immunosorbent assay tests.ResultsBacteria were detected in all samples by culture and molecular methods. A total of 154 gram-positive strains, of 188 strains isolated, were found in the root canals by culture. Enterococcus faecalis and Gemella morbillorum were the most prevalent species identified by the biochemical tests, whereas molecular analyses (nested-PCR) showed a high frequency of P. gingivalis, E. faecalis, and Fusobacterium nucleatum. LPS and LTA were detected in all samples, with mean values being 3.52 EU/mL and 597.83 pg/mL, respectively. Significant statistical correlations were found between levels of LTA and clinical features.ConclusionDespite the prevalence of gram-positives, the microbiota present in secondary/persistent infections showed a large variety of species. Within this diversity, associations were found between specific bacteria and clinical features. In addition, higher levels of LTA were statistically associated with larger periapical radiolucent areas, but no correlation between this feature and LPS was found.     

Evaluation of the presence of microorganisms from root canal of teeth submitted to retreatment due to prosthetic reasons and without evidence of apical periodontitis

Clinical Oral Investigations - The objective of this study was to evaluate the presence of microorganisms in the root canals (RC) of teeth submitted to endodontic retreatment due to prosthetic...     

Effectiveness of calcium hydroxide-based intracanal medication on infectious/inflammatory contents in teeth with post-treatment apical periodontitis

Objective

The objective of this work was to investigate in vivo the effects of calcium hydroxide-based intracanal medication (ICM) on the levels of bacteria, pro-inflammatory cytokines (PICs), and matrix metalloproteinases (MMPs) in root canals and periradicular tissues of teeth with failure of the root canal treatment and apical periodontitis.

Materials and methods

Twenty infected root canals of single-rooted teeth were randomly assigned into two groups according to the irrigant used for chemomechanical preparation (CMP) (n = 10 per group): G1 – 2% chlorhexidine (CHX) gel and G2 – 6% sodium hypochlorite (NaOCl). Root canal contents were taken by using paper points before CMP (S1) and after 30 days of calcium hydroxide-based ICM (S2). Microbial reduction was calculated by means of colony-forming unit count (CFU/mL), with PICs and MMPs (pg/mL) being measured by using enzyme-linked immunosorbent assay (ELISA).

Results

Culturable bacteria (101.2 ± 79.2), PICs (IL-1β 1.2 ± 0.4 and TNF-α 8.8 ± 4.7), MMP-2 (803.7 ± 96.4), MMP-3 (453.9 ± 229.3), MMP-8 (245.9 ± 122.4), MMP-9 (129.4 ± 29.6), and MMP-13 (70.8 ± 12.8) were present in all S1 samples. After 30 days of ICM (S2), a 99.5% microbial reduction was observed, together with a significant reduction of PICs in all groups. Overall, it was observed a decrease in the levels of MMPs (S2), except MMP-13, which was found in increased levels after ICM (P < .05), independently of the groups.

Conclusions

Calcium hydroxide-based intracanal medications have had a positive effect on the microbial reduction by decreasing the levels of PICs and MMPs. Both auxiliary chemical substances (i.e., 2% CHX and 6% NaOCl) presented similar effects when calcium hydroxide was used as intracanal medication.

Clinical relevance

Teeth with failure of the root canal treatment and apical periodontitis, and consequently with high levels of bacteria, PIC, and MMP, may present a better prognosis after a 30 days of a calcium hydroxide-based ICM.