Effectiveness in root canal disinfection and biocompatibility of a final in vitro irrigation protocol based on cellulases and a hyperosmotic solution

Objective: To evaluate the antimicrobial capacity and cell viability of a final irrigation protocol based on the use of a hydrolases enzymes mixture (HEM) and a hyperosmotic solution (HS) as an alternative to conventional protocols.

Methods: Root canals from 28 human first molars were used to develop multispecies anaerobic biofilms in standard reactors and irrigated with various protocols according to the following groups. Group A: control (sterile saline), group B: 2.25 % NaOCl, group C: 1 % NaOCl, group D: HS, group E: 100 U/mL HEM + 1 % NaOCl, group F: 100 U/mL HEM + HS, or group G: 100 U/mL HEM. The disinfection evaluation per group was carried out by CFU counting and Scanning Electron Microscopy (SEM). The viability was determined on fibroblasts.

Results: The F group, which consisted in irrigating with HEM + HS, had a biofilm elimination of over 5.33 (Log reduction), as well as the groups treated with NaOCl with eliminations of up to 5.34 (Log reduction). In addition, the evaluation of viability reflects a biocompatibility of the F group treatment, as opposed to the groups treated with NaOCl.

Conclusions: The irrigation protocols with HEM+HS and HEM+NaOCl turned out to be as efficient as the conventional protocol using NaOCl; moreover, the irrigation protocol with HEM+HS had low cell cytotoxicity in the viability assay when compared to cell cultures exposed to NaOCl.

Clinical significance: It is imperative that new and innovative ways are found for root canal therapy to ensure that the root canal system can be thoroughly cleaned.