Chemomechanical preparation with removal of infected tissues and microbial biofilms is the corner stone of root canal treatment. Since mechanical instrumentation alone cannot adequately disinfect root canals, complete cleaning and shaping involves irrigation with chemicals together with mechanical instrumentation.
In addition to shaping the root canal, the aim of chemical-mechanical preparation of root canals is to eliminate vital or necrotic tissue, microorganisms and their products, and dentin debris that result from instrumentation. However, the complexity of root canal anatomy together with microbial infection hinder this purpose.
Primary endodontic infection is characterized by the presence of a wide range of microbial diversity dominated by anaerobes. The polymicrobial profile of pulp infection involves both Gram-positive and Gram-negative bacterial species.
Besides, the apical third of the root canal system typically has a complex morphology and is difficult to clean. So, it is important to bring irrigants into contact with the entire canal surfaces along its total micro anatomic complexity for effective action especially in the apical portions .
Irrigating solutions used during endodontic handling act through direct contact with the targeted bacteria. However, irrigants have inadequate penetration depth. It is highly desirable that chemical substances selected as endodontic irrigants have antimicrobial and organic tissue dissolution properties besides serving in the debridement of the root canal system and not being toxic to the tissues .Sodium hypochlorite (NaOCl) has been the gold standard for irrigation because of its ability to dissolve organic matter and high antimicrobial potential.
Conventional needle irrigation is the most commonly employed technique for delivering irrigants into the root canal system. However, the disadvantage of conventional needle irrigation is its passive action, and inability to deliver solutions into the narrow anatomical features of the root canal system. Despite the high success rates of root canal treatment, reducing the bacterial load below the level that is required to assure healing has become the accepted goal. Hence, several irrigant activation systems have been developed to increase the effectiveness of irrigation by providing energy within the canal to disperse and move the irrigant around the canal system in anticipation of them removing biofilm more effectively.
Therefore, various activation and agitation systems have been introduced to improve the irrigation penetration and effectiveness. These systems include manual dynamic agitation, sonic, passive ultrasonic, photon initiated photoacoustic streaming (PIPS), laser, XP-endo Finisher file, and Easy-Clean (EC).
The XP-endo Finisher file is a new rotary file presented to be used after root canal instrumentation as a final step in order to improve irrigant penetration and root canal cleaning and disinfection. It is made from a special nickel-titanium (NiTi) MaxWire alloy Hence, it possesses the shape memory effect when inserted into the canal (M-phase changed to A-phase) and exhibits superelasticity during canal preparation.
EC is an irrigation activating device, using an acrylonitrile butadiene styrene plastic instrument designed to produce vigorous intracanal fluid agitation.It has advantages of promoting agitation along the whole length of the instrument with no risk of deforming the canal walls.
There are many methods to evaluate penetration of irrigant solution into root canal but most them laboratory or ex-vivo using dye marker as Rhodamine B stain and methylene blue, while other radiopaque marker as Iohexol are used clinically.
Radiopaque contrast media as Iohexol can be used to assess the effect of various irrigation activating techniques on irrigant penetration into root canals in vivo as they can be seen in dental radiographs. Iohexol has the advantage of being a low osmolality agent that it is readily available in a sterile, pyrogen-free, nontoxic solution. It is widely used for angiocardiographic studies, thoracic and lumbar myelography, and in contrast enhancement for brain computed tomography and imaging of salivary glands.
Activation of irrigantion was considered one important method of bacterial reduction beside decreasing biofilm formation in root canals. on the other hand, it was reported that the activation protocols facilitate the disinfection of anatomical complexities and dentinal tubules.
According to the current knowledge, there is few studies concerning the effect of different irrigation activation techniques on enhancing irrigant penetration into the apical third of root canals and on reducing microbial infection, so this study aims to evaluate irrigant penetration depth and microbial reduction after using different irrigation activation techniques.
