Sodium chloride and potassium sorbate: a synergistic combination against E nterococcus faecalis biofilms: an in vitro study

Incomplete disinfection of the root canal system is a major cause of post‐treatment disease. This study aimed to investigate the disinfecting property of organic acid salts and sodium chloride ( NaCl ), in a double‐hurdle strategy, on E nterococcus faecalis biofilms. First of all, the high‐throughput resazurin metabolism assay ( RMA ) was used to test a range of organic acid salts. Then, to gain more insight into the efficacy of sorbate salt solutions, 48‐h E . faecalis biofilms were evaluated in colony‐forming unit ( CFU ) assays. Chlorhexidine ( CHX ) and calcium hydroxide [ Ca(OH) 2 ] were tested in parallel as controls. Sorbate salt produced the largest and most significant reduction of fluorescence intensity in the RMA assay. Neither NaCl nor potassium sorbate ( KS ) alone induced a clinically relevant reduction of CFU counts after 1 h. Surprisingly, the combination of the two in a single solution had a synergistic effect on the inactivation of E . faecalis . Potassium sorbate amplified the efficacy of NaCl . Of the salts tested, NaCl with KS eradicated E . faecalis biofilms within 1 h. This study showed that the double‐hurdle strategy indeed leads to synergistic efficacy and is a possible next step in the complete disinfection of endodontic infections.