Optimal canal disinfection has been the subject of intense scientific research in the endodontic space in the past decade. Irrigants, irrigant combinations, activation methods and a host of different disinfection systems and methods have been studied and advocated. Regardless of the specific means used to facilitate disinfection, there are a number of literature based strategies in general agreement. These strategies include the following desirable elements (among others):
- greater volumes of irrigation are preferable to lesser
- higher concentrations of irrigant, within biologically tolerable limits, are preferable
- frequent irrigant replenishment
- removal of remnant organic matter (e.g. pulp tissue)
- removal of remnant inorganic matter (e.g. smear layer)
- elimination of vapor lock
- activation of irrigants (sonic, ultrasonic, negative pressure, mechanical, multisonic, laser activated, etc.)
- achievement of apical patency (to prevent blockage of the apical third with canal debris)
- maintenance of the apical foramen at its original position and size (to avoid and/or minimize irrigant extrusion)
- optimizing the apical size and canal taper for the canal anatomy
- passive delivery of irrigants (irrigants should never delivered under pressure or with a locked needle)
- a rubber dam must be used
- the chamber and canals must be cleared as soon as debris is generated to prevent apical debris propulsion
With the above clinical paradigms in mind, this Vista View blog was written to discuss an evidence based protocol for canal disinfection.
Disinfection begins with adequate yet conservative access, achievement of patency, and well-shaped canal systems. It is axiomatic that a well-shaped canal can be disinfected and obturated to a very high standard. The converse is true. Better prepared canal shapes facilitate apical penetration of irrigants and activation throughout the entire canal, from orifice to apex. Irrigants and activation methods are designed and utilized to remove remnant pulpal tissue, smear layer, bacteria, biofilm, and all canal debris. The endodontic literature is absolutely clear that cleaner canals optimize endodontic success rates in combination with post endodontic coronal seal.
In broad terms, the goals of irrigation mentioned above are achieved through the use of a tissue dissolution irrigant, chelator, bactericide and activation. I use Chlor-XTRA™ (tissue dissolution and bactericidal irrigant) in combination with SmearOFF™ (chelating irrigant) and ultrasonic activation using the cordless EndoUltra® activator. The combination of these irrigants and the EndoUltra® provides a simple, inexpensive and highly effective system to provide optimal disinfection.
Sodium hypochlorite (NaOCl) is the most commonly used irrigant due to its excellent antibacterial effects, tissue dissolution properties, and action against biofilms. Commonly, household bleach is used as a source of NaOCl. However, the manufacturing and storage of household bleach is not controlled, which can result in significantly varied NaOCl concentrations during clinical use as NaOCl degrades over time and at elevated temperatures. Furthermore, off-the-shelf commercial bleach does not have surfactants to reduce surface tension and improve canal wetting.
By contrast, Chlor-XTRA™ is an enhanced 6% NaOCl solution designed for irrigation, debridement and cleansing of root canals during and after instrumentation. Compared to standard NaOCl, Chlor-XTRA™ offers greater oxidizing power, wetting ability, tissue digestion and lower surface tension which improves irrigant penetration into canal complexities.
EDTA removes the smeared layer of inorganic canal wall debris that results from root canal instrumentation. Such debris blocks dentinal tubules and becomes packed into otherwise inaccessible canal anatomy (isthmuses, apical deltas, fins, cul de sacs, etc). Sodium hypochlorite kills bacteria and dissolved organic material, however, it cannot alone remove the smear layer. It requires a chelator like EDTA to dissolve inorganic canal debris to facilitate irrigant penetration throughout the canal system.
As a chelator, SmearOFF™ removes the smear layer and provides a coincident bactericide (in the form of chlorhexidine, CHX) potentiated by surfactants similar to Chlor-XTRA™. Common chelating agents like 17% EDTA do not have a bactericidal component nor surfactants. SmearOFF™ can be used independently without Chlor-XTRA™, but these two solutions are optimally used in tandem with the added benefit that their mixture does not form parachloroaniline (PCA) or a precipitate, which typically occurs when standard NaOCl is mixed with chlorhexidine-based irrigants.
The lack of precipitate formation provides a significant benefit because it eliminates the required rinsing steps between CHX and NaOCl irrigants, or vice versa. In essence, SmearOFF™ and Chlor-XTRA™ provide the only true 2-step irrigation protocol as no rinse is needed when using Chlor-XTRA™ in conjunction with SmearOFF™.
Endodontic irrigants are optimally activated for maximum effectiveness. Abundant scientific literature shows that activation by means of mechanical, sonic, ultrasonic and negative pressure irrigation methods, among others, all enhance the antimicrobial properties of irrigating solutions. Acoustic streaming and cavitation of intracanal irrigant via ultrasonic activation has been shown to significantly enhance cleansing of complex anatomy.
EndoUltra® is the only cordless activator unit capable of generating ultrasonic tip frequencies (~45,000 Hz) and is my chosen ultrasonic irrigation activation method. EndoUltra® disrupts biofilm, reduces bacteria levels, improves irrigant penetration and removes vapor lock. The multi-use autoclavable ultrasonic activation tips will not engage or remove tooth structure.
To order Chlor-XTRA™, SmearOFF™, or the EndoUltra®, please visit vistadental.com. If there is a topic you would like addressed in the Vista View, or you have a clinical question about Vista products, contact us at [email protected]. See you at the Apex.
Note: Dr. Mounce is a practicing endodontist who writes and lectures nationally and internationally. He was the Chief Dental Officer of Vista Dental. Literature references available upon request.