Introduction and aim: Chlorhexidine Hydrochloride [Chx.HCl] has a broad-spectrum antibacterial effect, sustained action and low toxicity so it has been recommended as a potential root canal irrigant. The aim of this study was to improve the penetration ability, cleansing and antibacterial effect of Chx.HCl using a newly formulated Chx.HCl nanoemulsion and use it as root canal irrigant. Methods: Chx.HCl nanoemulsions were prepared using two different oils; Oleic acid and Labrafil M1944CS, two surfactants; Tween 20 and Tween 80 and co-surfactant; Propylene Glycol. Pseudoternary phase diagrams were constructed to designate the optimum systems. The prepared nanoemulsion formulae were evaluated for their drug content, emulsification time, dispersibility, droplet size, in-vitro drug release, thermodynamic stability, In-vitro antibacterial activity and ex-vivo study for the selected formula. Comparisons were made of Chx.HCl nanoemulsion with two different concentrations 0.75% and 1.6% vs Chx.HCl normal particle size as root canal irrigant for their penetration ability, cleansing effect and antibacterial effect. Results: The selected formula was F6 with composition of 2% Labrafil, 12% Tween 80 and 6% Propylene glycol. It has small particle size (12.18 nm), short emulsification time (1.67 seconds), and fast dissolution rate after 2 minutes. It was found to be a thermodynamically/physically stable system. The higher concentration of Chx.HClnanoemulsion1.6% shows the best penetration ability compared to Chx.HCl normal particle size due to the smaller particle size. Chx.HCl nanoemulsion 1.6% has the lowest mean value of the remaining debris surface area (2001.47 µm 2 ) when compared to normal particle size material (2609.56 µm 2 ). Conclusion: Chx.HCl nanoemulsion preparation has better cleansing ability and antibacterial effect with high efficacy on Enterococcus faecalis , where high reduction rate or complete eradication of bacterial cells has been achieved.

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Aim:The purpose of this study is to evaluate the antibacterial effect of Diode laser 980 nm, EndoVac and passive ultrasonic irrigation ex vivo. Methods:One hundred and five maxillary central incisors were standardized to 15mm in length. All samples were prepared using Protaper Universal rotary nickel titanium system till size # F4 then contaminated with E. faecalis. The irrigation protocol used was 2.5% sodium hypochlorite followed by 17% EDTA. Samples were randomly divided into 5 groups (n= 20) according to the irrigant activation method. LAI group, Diode laser 980nm. API group, EndoVac system. PUI group, passive ultrasonic activation. The positive control group, in which the irrigating solution was not activated and the negative control group in which the samples were not subjected to irrigation or activation. Residual bacteria were collected with sterile paper point, plated onto BHI media and incubated (37 °C, 48 h) to determine the colony-forming units (CFU mL-1). Data were analyzed using one-way ANOVA followed by performance of Tukey post hoc tests. Significance was set at p < 0.05. Scanning electron microscopy was used to investigate the changes in biofilm. Results:There was a statistically significant reduction in the mean numbers of colony-forming units among all groups. However, none of the activation methods was able to kill E. faecalis biofilm completely. The LAI group behaved most effectively among all groups. Conclusion:The adjunctive use of 980nm laser is an effective method for bacterial reduction after chemo-mechanical instrumentation of the root canal.