Effects of Oral Melatonin on Neurosensory Recovery Following Facial Osteotomies - A Randomised, Controlled Clinical Trial

Background:

Orthognathic surgery is a commonly accepted treatment modality for the management of dentofacial deformities. Although in many cases, satisfying, if not excellent, aesthetic and functional results can be obtained with orthognathic surgeries, this is not without risks; and one of the most prevalent and long-term complication encountered is neurosensory disturbance either in the inferior alveolar nerve or the infraorbital nerve depending on the jaw receiving the osteotomy. A systematic review by Jędrzejewski et al. in 2015 reported cranial nerve injury/sensitivity alteration to be the most common complication after orthognathic surgery and is seen in 50% of cases, and almost all patients will report altered sensation in the immediate post-operative period. Although this will decrease over time, Henzelka et al. have reported a 3% incidence of paresthesia in the inferior alveolar nerve 1 year post-surgery, and Thygesen et al. reported sensory changes in the infraorbital nerve in 7 to 60% of patients depending on site of measurement 1 year post-surgery. In Hong Kong, a 10-year retrospective study of 581 patients by Lee et al. in 2013 reported a 5.9% rate of neurosensory disturbance 1-year post-orthognathic surgery. Of these cases, the majority affected the inferior alveolar nerve, and the combination of ramus osteotomies together with anterior mandibular osteotomies significantly increased the chances of permanent neurosensory disturbance.

Biosynthesis of Melatonin:

Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone that is endogenously produced and secreted by the pineal gland in the brain in a circadian rhythm, with a plasma concentration highest at night and lowest during the day. Its normal physiological roles in humans are to regulate diurnal rhythm, sleep, mood, immunity, reproduction, intestinal motility, and metabolism. Oral exogenous melatonin has been used in the management of jetlag and other sleep disorders. Recently, animal and human studies have shown melatonin to improve tolerance to tourniquet pain in patients receiving hand surgery performed under regional anaesthesia, to improve dyspnea in patients with chronic obstructive pulmonary disease, and to have a neuroprotective and neuroregenerative effect after nerve injuries.

Pharmacology of Melatonin: