Markus Haapasalo, DDS, PhD, RCDC(C)
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The most common endodontic infection, apical periodontitis, is caused by invasion of bacteria deep into dentin and the root canal space. Therefore, the short- and long-term success of endodontic treatment depends on eliminating microbes from the root canal system and preventing reinfection via coronal leakage.
All treatment should be based on careful diagnosis followed by a decision on treatment and information to the patient. Treatment consists of access cavity preparation, location of all root canals, instrumentation, irrigation and disinfection, root filling, and coronal restoration of the tooth.
Although instrumentation often gets most of the attention in endodontic media, it is important to remember that there are two major goals for instrumentation; it creates the form and space to allow effective irrigation of the canal, and at the end of treatment, placement of an adequate root filling.
Irrigation plays the main role in eradication of microbes from the root canal system, while root filling is important in an effort to eliminate the possibility of reinfection. Instrumentation, irrigation, locally used disinfecting agents, and root filling (sealer) all contribute to the killing and removal of microbes from the infected root canal, with irrigation regarded as the most important factor.
The effect of mechanical washing, reduction of friction, and control of temperature are all important underlying reasons for irrigation; however, the most important tasks are dissolution of organic and inorganic tissue, and killing of the microbes.
It is well recognized that none of the currently available irrigating solutions truly master all of these tasks when convenience and effectiveness are taken into consideration; therefore, use of a minimum of two solutions to complete these tasks is necessary.
Sodium hypochlorite is the solution of choice during instrumentation due to its strong antibacterial effect and ability to dissolve organic debris (e.g., necrotic pulp tissue); however, hypochlorite cannot remove smear layer that has formed on canal walls that have been in contact with rotary preparation instruments.
Smear layer removal is an important part of the treatment because it contains microorganisms and microbial antigens embedded in the amorphous mixture of inorganic and organic dentin and necrotic tissue. Smear layer has traditionally been removed by 17% EDTA (ethylenediaminetetraacetic acid), and citric acid has also been used for this purpose.
Hypochlorite irrigation during instrumentation dissolves the organic matter in smear layer, and EDTA removes the inorganic substance, revealing a clean canal wall with open dentinal tubules; however, EDTA lacks the antibacterial effect that is highly desirable when removing the smear layer. Recent observations of the effect of hypochlorite on dentin (weakening, erosion) suggest caution regarding the use of hypochlorite as the final rinse after EDTA.
QMix™ 2in1 is a new root canal irrigant built on the effectiveness of EDTA that removes smear layer at least as effectively as 17% EDTA, and has proven to be a highly effective antimicrobial agent (≥99.99% disinfection per independent studies).
It kills planktonic (free-floating) bacteria, including Enterococci, within seconds, and research shows it is capable of penetrating biofilms due to its unique blend of antibacterial substances and their combined synergistic effect. QMix™ 2in1 is a premixed, ready-to-use, colorless and odorless solution that is free of antibiotics. No evidence of tooth staining has been observed in laboratory conditions following use of this solution.
The proprietary formula is based on an advanced chemical design to minimize any undesirable reactions with other root canal irrigants. The manufacturer (DENTSPLY Tulsa Dental Specialties, Tulsa, Okla.) recommends 60 to 90 seconds of continuous irrigation as the final rinse of the root canal before root filling.
Markus Haapasalo, DDS, PhD, RCDC(C), is professor of endodontics, University of British Columbia, Vancouver, Canada. He is the chair of the Division of Endodontics, head of the Department of Oral Biological and Medical Sciences, and a fellow of the Royal College of Dentists. Reach him at [email protected].
