(Kiosk 4) Facial Neuropathy Following Root Canal Hypochlorite Toxicity: A Case Report

Case Diagnosis: Neuropathy of the left facial nerve’s buccal branch secondary to hypochlorite toxicity

Case Description or Program Description: 25 year old female with no medical history developed caries and subsequent infection of her bottom left wisdom tooth (#17) which was resistant to amoxicillin. She underwent root canal involving the use of hypochlorite solution for intraprocedural disinfection. She subsequently developed left facial droop particularly near the mouth, and complained of numbness and tingling of the left cheek as well as “clogging sensation” in her left ear. The patient’s symptoms persisted and ultimately underwent electrodiagnostic study of her face. Upon physical exam, there was significant left facial droop primarily around the lips. The forehead appeared unremarkable and the patient was able to close her eyes. Sensation was normal and symmetric throughout the face. Direct stimulation of the left and right facial nerves were normal. EMG of the left orbicularis oris revealed decreased recruitment, whereas the frontalis, nasalis, mentalis, and orbicularis oculi were normal. The patient was ultimately diagnosed with an incomplete isolated neuropathy of the buccal branch of the left facial nerve.

Setting: Outpatient academic EMG clinic

Assessment/Results: Given the close proximity and temporal relationship between the root canal procedure and facial nerve palsy, the patient was diagnosed with an incomplete neuropathy of the left facial nerve’s buccal branch secondary to hypochlorite toxicity.

Discussion (relevance): Sodium hypochlorite (NaOCl) is an irrigant that is commonly used as a disinfectant and debris dissolvant during dental procedures because of its high pH. However, extravasation of NaOCl can cause devastating damage to nearby tissues. Commonly reported examples range from simple erythema and edema of the nearby superficial skin to intraoral ulcers and mucosal necrosis. However, cranial nerve injury is rarely seen given their deeper location in relation to dental procedures.

Conclusions: Facial nerve palsy is a rare but potential adverse event of hypochlorite toxicity during dental procedures.