Final answer:
The recommended step in the treatment protocol for a sodium hypochlorite accident during endodontic therapy is immediately rinsing with water.
Step-by-step explanation:
The Hales et al (2001) treatment protocol for the management of a sodium hypochlorite accident during endodontic therapy recommends immediately rinsing with water as a recommended step. Sodium hypochlorite, which is an inexpensive bleach and germicide, can cause damage if it comes into contact with soft tissues in the mouth. Rinsing with water helps to dilute and remove the sodium hypochlorite, reducing potential harm.