Melatonin As Pain Therapy & Other Insights From The American Academy of Orofacial Pain

Recently I attended the American Academy of Orofacial Pain’s Annual Literature Review, which this year was focused on sleep and pain. Of the scientific articles that were selected and distributed to the participants prior to the meeting,  three stood out to me as particularly interesting.

These three articles discussed melatonin as pain therapy, assessing mandibular advancement appliance positioning for sleep related breathing disorders, and the use of high-resolution pulse oximetry (HRPO) as a screening tool in children.

Here are some highlights:

Melatonin has been used for a number of years to help normalize circadian rhythms resulting in sleep improvement. This strategy for improving sleep has found it’s way into the world of pain management, as better sleep has been associated with improved pain thresholds. For patients where melatonin improves sleep, the pain resulting from sleep bruxism can be reduced.

In addition, for patients with somatic pain (such as muscle/joint, for instance) secondary to injury-induced inflammation, studies have shown that melatonin can induce pain reduction due to the inhibition of prostaglandin release.

Beyond normalization of the circadian rhythm, there is now evidence that melatonin also has an independent analgesic effect. This analgesic effect was diminished in the presence of naloxone (opiate antagonist), suggesting that melatonin’s pain-reducing capacity is due to its ability to activate central pain modulation systems.

Melatonin has also been shown to diminish the suffering associated with neuropathic pain and the associated allodynia (pain prompted by normal life stimuli). As migraine headaches are associated with central pain mechanisms, recent studies show the use of drugs that bind to melatonin receptors can diminish the frequency and duration of migraine attacks. Melatonin has also shown benefit in reducing persistent toothache pains that have a neuropathic origin.

The pain reduction capacity of melatonin has been compared to that of gabapentin (Neurontin) in the treatment of neuropathic pain.

Due to melatonin’s high safety profile it should merit attention for those suffering with chronic orofacial pain. Time-release melatonin preparations are now available.

The initial treatment positions using mandibular advancement appliances (MADs) to treat OSA have arbitrarily been set at somewhere between 50-75% of maximum protrusion. No studies ever verified these frequently made clinical recommendations.

When using MADs for OSA, the intent has been either to prevent mandibular retrusion during sleep or to actively pursue advancement of the mandible. The decision to choose one direction or the other has often been influenced by the severity of the airway obstruction, the specific maxillo-mandibular profile of the patient, the Mallampati index, the size of the tongue, and the ability of the patient to breath through his or her nose.

Recent studies have shown that reduction of the AHI and improvement of oxygen saturation can occur by setting the initial appliance position to a centric occlusion (MIP) position and preventing retrusion of the mandible from that position. In particular, I have found in patients who are clenchers (and as a result bring the appliance rims into contact in this neutral position and don’t move back) this is a strategy that is often effective. If results are inadequate, the titration forward can then commence.

Checking the efficacy MAD appliances is critical if you want to determine whether the goals of treatment are being reached. Certainly, home sleep testing devices are a way to achieve this investigation, but the use of high-resolution pulse oximetry may be even a better option. To better understand the use of high-resolution pulse oximetry, HRPO check out Dr. James Metz’s video on You Tube .

In children that are suspected of having airway challenges, it is difficult, if not impossible, to get an overnight sleep lab study and or use Home Sleep Testing systems because many are not tolerated and/or feared by young patients. In a population where an airway problem may predispose to learning and emotional development concerns, using high-resolution pulse oximetry (HRPO) appears to be an excellent screening tool.

Recent studies suggest that HRPO has 75.2 % accuracy for diagnosing apnea in kids. If the HDPO identifies five desaturation events per hour, it is likely that on a polysomnogram (PSG) there will be an AHI> 5. (AHI of 1-5 in a child is mild OSA, 5-10 is moderate.)

With this type of screening now available, pediatric dentists, orthodontists and all general dentists who see kids are now in the position to identify airway problems early on – if they include basic questioning and observation in their every day routines.

I welcome your thoughts.