Introduction and Aim: Sodium hypochlorite (NaOCl) has proven to be the chosen irrigator in modern practice due to its high tissue solution power, antibacterial, and lubricant properties. This study aimed to use a Lipid-Free Nanoemulsion (LF/NE) to improve the penetration efficiency, antibacterial effect, tissue dissolving, and cleansing ability of NaOCl. Moreover, masking NaOCl taste when used as a root canal irrigant.

Methods: NaOCl LF/NE were comprised of a mixture of surfactants (Tween20 and Tween 80) and cosolvents (Transcutol HP and propylene glycol). The desired size range for dispersed globules was achieved using an ultrasonicator. After then, it was left to equilibrate. To designate the best systems, pseudoternary phase diagrams were constructed. The drug content, dispersibility, droplet size, drug release, and antibacterial activity of the formulae were all evaluated. Ex-vivo study was performed for the selected formula. NaOCl LF/NE was compared with two different concentrations levels 0.75 and 1.6% versus 5.25% NaOCl normal particle size and prepared Chlorhexidine Hydrochloride (CHX.HCl) nano-emulsion (in previous work)for their penetration ability as a root canal irrigant, Antibacterial activity cleansing effect, and tissue dissolving were done.

Results: formula F3 with a composition of 33%Tween 80 and 33% Transcutol HP was selected. It had a small particle size (106 nm) and a maximum dissolution rate after 2 min. It was proven a thermodynamically physically stable system. The ex-vivo study results showed the deepest penetration with a mean depth of 75.71µm for 1.6% NaOCl LF/NE. The result was higher than the previous work of CHX.HCl as the mean for CHX.HCl nanoemulsion irrigant was 11.29µm.

Conclusion: NaOCl LF/NE had better ability in the cleansing of the root canals than both of NaOCl normal particle size and CHX.HCl with high efficacy as an antibacterial agent on Enterococcus faecalis