20 June 2023

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New 2-in-1 root canal irrigants

Lara Figini

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Disinfection of the root canal system is critical to endodontic success and can be achieved through mechanical instrumentation, irrigation with disinfectant solutions, and the application of intermediate root canal dressings. Literature studies have demonstrated that mechanical instrumentation alone cannot completely engraft microbes present in accessory canals, anastomoses and deep dentinal tubules. Approximately 35-53% of the root canal surface remains intact during mechanical instrumentation which results in biofilm retention. 

This highlights the need for a root canal irrigant capable of removing the smear-layer and disinfecting the root canal system at the same time. Manufacturers have now combined a chelating agent and a disinfectant in a single solution (2-in-1 irrigant). The use of this type of irrigant would presumably reduce treatment time and should increase the effectiveness of root canal therapy.

These types of 2-in-1 irrigants include:

• QMix 2 in 1 (Dentsply Sirona, Charlotte, NC, USA) able to remove the smear layer as effectively as 17% EDTA and is an effective antimicrobial agent against Enterococcus faecalis (E. faecalis) biofilms.
• Irritrol (Essential Dental Systems, Hackensack, NJ, USA) which is a recently introduced single-phase disinfectant endodontic irrigating solution consisting of EDTA and chlorhexidine (CHX).
• SmearOFF (Vista Dental Products, Racine, WI, USA) is a recently introduced smear layer removal agent in endodontics. According to the manufacturer, mixing SmearOFF with NaOCl does not cause precipitation. This negates the need for a second rinse after NaOCl irrigation. To date, no comparative studies are available to evaluate the physical and chemical characteristics properties of 2-in-1 irrigation solutions.

Materials and methods

In a study published online in April 2023 in the Journal of Dentistry, the authors evaluated the ability to remove the smear layer from canals, the antibacterial activity and the cytotoxicity of three new 2-in-1 root canal irrigants (chelator + antibacterial). 

Forty single-rooted teeth were mechanically instrumented and irrigated with QMix, SmearOFF, Irritrol or 0.9% saline (control group). Each tooth was evaluated for smear layer removal using scanning electron microscopy. Precipitation after interaction with sodium hypochlorite (NaOCl) was evaluated with 1H nuclear magnetic resonance and mass spectroscopy. Laser scanning confocal microscopy was used to evaluate the antimicrobial activity of irrigants against Enterococcus faecalis biofilms.

Clonogenic assays were performed on Chinese hamster V79 cells to evaluate the short-term and long-term cytotoxicity of irrigants.

Results

No significant difference was found between QMix and SmearOFF in the elimination of smear layers from the coronal third and middle third of the root canal. In the apical third, SmearOFF has been shown to be able to remove the smear-layer more effectively. Irritrol has been shown to incompletely remove the smear-layer from all thirds of the channel. When mixed with NaOCl, precipitation was only evident with Irritrol. QMix demonstrated a higher E. faecalis cell death rate and lower biovolume. SmearOFF showed a greater decrease in biovolume than Irritrol, although Irritrol led to a higher cell death rate. Irritrol was more cytotoxic than all other short-term irrigants. In terms of long-term cytotoxicity, both Irritrol and QMix were found to be cytotoxic.

Conclusions

From the data of this study, it can be concluded that QMix and SmearOFF offer better results in the removal of the smear layer and in the antimicrobial activity. QMix and Irritrol are more cytotoxic than SmearOFF.

Nidambur Vasudev Ballal et al. "Biological and chemical properties of 2-in-1 calcium-chelating and antibacterial root canal irrigants," Journal of Dentistry, Volume 134, 2023, 104526, ISSN 0300-5712, https://doi.org/10.1016/j.jdent.2023.104526.