Irrigating or irritating – A letter to the editor

Dear Editor, Endodontic literature has given prime importance to root canal debridement and inherent irrigation which is carried out in due course of instrumentation and thereafter.[1] However, we are pretty much unsure of the effects which tend to happen at the periapical terminus or the periapical region after root canal irrigation. It is now clear from the literature evidence that irrigation is key for effective root canal debridement and cleaning.[1] Primary root canal irrigation and irrigant activation are the two critical aspects followed during the endodontic treatment. However, the in vitro literature focused on computational fluid dynamic analysis which elaborates on the forces induced in the periapical region in due course of the irrigation[2] and activation.[3] However, clinically it is impossible and unrealistic to expect an operator to have an idea of the forces and pressures induced by them during the irrigation. From the stage of root canal instrumentation, manual irrigation to irrigant activation, there is continuous contact of the irrigating solution with the periapical area. However, there is no clear-cut idea of the solution which reaches the terminus and way beyond that. Until and unless the apical constriction is not violated, the chances of irrigant extrusions are quite uncommon clinically. The reason is the periapical tissue which offers resistance for extrusion during the irrigation.[4] However, it is beneficial to understand the aftereffects of irrigation at the periapex and the region beyond the apical terminus and at the periapical region too. Usually, the literature showed beneficial periapical healing on using various irrigation systems with less periapical cell inflammatory infiltrate, with no difference in various irrigation systems tested.[5] To have a basic idea, it is better to understand the effect of irrigating solutions at the periapical region when they come in contact with the periapical tissues. The cytotoxicity is severe when there is a clinically noteworthy volume of sodium hypochlorite extrusion.[6] However, the effect is least or almost nil with the other irrigating solutions.[7] However, it is never the irrigating solution alone which gets extruded unless an operator forces the needle pushing the solution with pressure.[2] It is always the debris which gets extruded along the irrigant. Instrumentation-related dentinal debris which might get mixed with the irrigating solution sometimes gets forced into the periapical region. The inflammatory sequence thereafter is quite different and transient. However, the effects after solution extrusion are quite different, and clinical and histological sequences differ based on the irrigating solution type, the volume of solution extruded, and the physiological and pathological nature at the periapex.[6] There are a series of histological responses that tend to happen which are clinically depicted as the inflammatory sequences. The physiological body's immune responses are usually enough to tackle them. Multiple periapical sequences tend to occur leading to phagocytosis. The aftereffects of solution extrusions include the transient necrosis of the region later transforming into a physiological tissue or scar depending on the intensity of extrusion.[6] The hydrodynamic forces induced during irrigation vary depending on the syringe needle type used and the level of needle placement.[2] The same applies based on the activation device choice and level of tip placement.[3] Pushing of dentinal debris is quite common if adequate disinfection and cleaning have not been followed during the irrigation. In those cases when the activation is carried out, the chances of extrusion of dentinal debris or dentinal mud are quite higher. Hence, to avoid debris extrusion, effective smear removal is important during irrigation. However, to prevent the irrigant extrusions, the usage of unbound side vented needles in an optimally prepared root canal at continuous oscillations would prevent the extrusions related to syringe needle irrigation. Care must be ensured on preparing the apex to as minimum as clinically realistic. Overzealous preparation sizes tend to extrude the root canal contents more often. Another prime factor is the forces induced intentionally during the root canal irrigation. Never push the needle nor the irrigating solution during the irrigation. Even the activation tip should always be 2 mm short and oscillated passively. Hence, considering all these factors, the root canal irrigation process should always be a passive phenomenon. Care should always be taken on apical forces, thus improving the lateral shear stresses and enhancing the overall debridement.[2] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.