Inadvertent injection of formalin mistaken for local anesthetic agent: report of a case.

Chemical facial cellulitis, while commonly seen in domestic accidents or attempted suicide, is uncommon in the dental office and hence rarely addressed in the dental literature. We present an unusual case of chemical facial cellulitis caused by inadvertent injection of formalin into the soft tissues of the oral cavity, which was mistaken for local anesthesia solution. This report comprises the immediate symptoms, possible root cause, and management of the difficult situation. We also provide some guidelines to avoid such unfortunate events.