Influence of Root Canal Irrigation Protocol on Sealer Penetration into Dentinal Tubules

Abstract

Effective elimination of microbes, dentin disinfection, and fluid-tight seal of the prepared canal system are the determining
factors in the long-term success of the root canal therapy. Although mechanical instrumentation has a major role in canal
formation, it will inevitably result in a smear layer which blocks dentinal tubules hindering the absorption of endodontic
sealers. Intrusion of the sealers into such tubules is regarded as a favorable effect, which advances mechanical interlocking,
decreases microleakage, and leads to bacterial entrapment. The irrigation protocol that is used in the course of root canal
preparation is a very critical one that defines the dentinal tubule openness and sealer penetration.
Sodium hypochlorite is the most common irrigant in dissolving organic tissues and antimicrobial action, however, it
fails to act on the inorganic part of the smear layer. The removal of this inorganic fraction can be successfully done using
chelating agents like ethylenediaminetetraacetic acid (EDTA) and citric acid, and this increases the tubule exposure.
Moreover, the order and process of delivery of irrigation such as syringe irrigation process, negative pressure, ultrasonic
or sonic agitation, and laser activation have a significant impact on irrigant penetration and cleanliness. Concurrent
application of sodium hypochlorite and a chelating agent especially when advanced agitation methods are used has been
repeatedly proved to enhance sealer penetration.
The physicochemical characteristics of sealers are also important, in terms of viscosity, flow, setting time and interaction
with the dentin substrate. Epoxy resin based and bioceramic sealers exhibit increased tubular penetration over traditional
zinc oxide-eugenol based formulations particularly in the event of optimal irrigation being undertaken.
In summary, irrigation protocols have a great effect on the level of sealer penetration into dentinal tubules, for which the
resultant effect is on the quality of root canal seal and the long-term outcomes of the treatment.