Efficacy of reciprocating and ultrasonic activation of 6% sodium hypochlorite in the reduction of microbial content and virulence factors in teeth with primary endodontic infection

Efficacy of reciprocating and ultrasonic activation of 6% sodium hypochlorite in the reduction of microbial content and virulence factors in teeth with primary endodontic infection:

Abstract

Aim

To evaluate in a clinical trial the efficacy of reciprocating and ultrasonic activation of 6% sodium hypochlorite (NaOCl) in microbial composition and reduction of microbial load as well as in levels of lipopolysaccharide (LPS) and lipoteichoic acid (LTA) in teeth with primary endodontic infection.

Methodology

Samples were collected from 24 root canals with pulp necrosis and periapical lesions, before and after chemo‐mechanical canal preparation. The teeth were randomly divided according to the activation protocol as follows: control group without activation (WA, n = 8), reciprocating activation group using Easy Clean tip (EC, n = 8) and ultrasonic activation group using Irrisonic insert (US, n = 8). Microbiological specimens were processed using a culture technique and microbiota composition was analysed by using the checkerboard technique. The levels of LPS and LTA were quantified using limulus amebocyte lysate (LAL) and enzyme‐linked immunosorbent assay (ELISA), respectively. The Fisher's exact test, Kruskal Wallis, Dunn and Wilcoxon’s test with a significance level of p < 0.05 were used for statistical analysis.

Results

All initial specimens had a growth of viable bacteria in fastidious anaerobe agar (FAA), with an average of 10⁵ CFU/ml, whereas only one case had such growth after chemo‐mechanical canal preparation. LPS and LTA were recovered in 100% of the cases. Chemo‐mechanical canal preparation significantly decreased the levels of LPS and LTA (p < 0.05), but no significant differences were found between the groups (p> 0.05). Through the checkerboard technique, bacteria were found in 100% of the initial specimens with concentrations between < 10⁵ and 10⁶. The most frequently identified microorganisms were Prevotella nigrescens and Enterococcus hirae. After chemo‐mechanical canal preparation, many species were not detected in any the three groups tested. A significant reduction occurred in Group US, followed by Groups EC and WA.

Conclusions

Activation of 6% NaOCl reduced the levels of LPS and LTA without a difference between the groups. However, ultrasonic activation was associated with a greater reduction in the microbial load within root canals.