Accidental intraoral injection of formalin instead of local anaesthetic represents a rare but significant iatrogenic emergency in dental practice. Although formalin is an essential fixative for histopathology, its highly caustic nature makes it dangerous in the operatory environment when stored improperly. The incident typically occurs when colorless solutions are kept in unlabeled or repurposed local anaesthetic vials, a practice still prevalent in some clinical settings in India. Once injected, formalin produces immediate coagulative necrosis, severe inflammation, oxidative stress, and potential systemic toxicity. Published literature shows that all reported cases of such incidents originate from India, highlighting unique workflow and storage challenges in these settings. This review provides an in-depth analysis of the chemical properties of neutral buffered formalin (NBF), mechanisms of fixation, tissue injury patterns, clinical presentation, evidence-based management strategies, prevention, and medico-legal implications. Recommendations emphasize strict labelling, proper storage, clinician supervision, and staff training to eliminate the risk of such preventable events.
