Antimicrobial potential of new diclofenac hydrogels for disinfection in regenerative endodontics: An in vitro and ex vivo study.

AIM There is a need to explore new alternatives for root canal disinfection in regenerative endodontics, since the current strategies are far from ideal. Currently, the potential use of diclofenac (DC) is being investigated for controlling root canal infections. The objective was to evaluate the antimicrobial efficacy of novel DC-based hydrogels (DCHs) against polymicrobial biofilms grown in radicular dentine and root canals, and to compare results with triantibiotic (TAH) and diantibiotic (DAH) hydrogels, and calcium hydroxide (Ca(OH)2 ). METHODOLOGY The in vitro antimicrobial activity of intracanal medicaments was evaluated against 3-week-old polymicrobial root canal biofilms grown on human radicular dentine. Dentine samples were obtained and randomly divided into the study groups (n = 4/group): 1) 1mg/mL TAH; 2) 1mg/mL DAH; 3) 5% DCH; 4) 2.5% DCH; 5) 1.25% DCH; 6) 1mg/mL DAH +5% DCH; 7) Ca(OH)2 paste; 8) positive control. The microbial viability, in terms of percentage of intact cell membranes, was assessed after 7 days by confocal scanning laser microscopy (CSLM). The ex vivo efficacy of intracanal medications was evaluated in root canals infected with a polymicrobial suspension. Intracanal microbiological samples at baseline (S1) and 7 days post-treatment (S2) were taken; microbial quantification and cell viability were assessed by quantitative polymerase chain reaction (qPCR) and flow cytometry (FC). The mean Log10 of bacterial DNA copies in root canal samples before (S1) and the Log10 reduction of DNA copies S1-S2 in qPCR were recorded. The absolute value of total cells stained, and the percentage reduction of intact membranes cells after treatment (S1-S2), were analyzed by FC. Global comparison was done using the Kruskall-Wallis test, while the Mann-Whitney U test was used for pair-by-pair comparison. RESULTS CSLM analysis indicated that the greatest effectiveness was obtained with 5% DCH, showing significant differences with respect to the other groups (p< 0.001). In root canals, the highest Log10 DNA reduction S1-S2 was obtained with 5% DCH and TAH, with no differences between them. The results of FC showed that only 5% DCH proved significantly superior to the other treatments. CONCLUSIONS Sodium diclofenac hydrogels demonstrate antimicrobial efficacy against endodontic biofilms.