The most crucial factor in effective root canal irrigation is the volume of irrigating solution used. Adequate volume ensures thorough flushing out of debris, bacteria, and necrotic tissue from the complex root canal system, including inaccessible areas and lateral canals. Higher volumes increase the mechanical cleansing effect and improve the penetration of the irrigant, enhancing disinfection. While concentration, type, and temperature influence efficacy, they are secondary to ensuring sufficient irrigant reaches all parts of the canal system. Hence, maintaining an ample volume is essential for optimal debridement and successful endodontic therapy.

Reference: Cohen's Pathways of the Pulp, 12th Edition.