Adjunctive treatment of chronic migraine using an oral dental device: overview and results of a randomized placebo-controlled crossover study

Abstract

Objective: To assess the nocioceptive input of habitual nocturnal jaw clenching that acts as a contributing factor in migraine pathogenesis.

Background: Habitual nocturnal jaw clenching has been implicated as a trigger, particularly in those whose headaches are present upon waking or shortly thereafter. Nocturnal EMG studies of patients diagnosed with migraine show nearly twice the temporalis clenching EMG levels and double the bite force as matched asymptomatic controls, leading to the speculation that parafunctional clenching activity may have some role in headache pathogenesis. The NTI (Nociceptive Trigeminal Inhibition) oral device is a dental splint designed to reduce nocturnal jaw clenching intensity and is FDA approved for the prevention of medically diagnosed migraine pain based on open label studies. There are no prior placebo-controlled trials to assess the migraine prevention efficacy of the NTI splint. This is the first placebo-controlled cross-over study to assess the efficacy of the NTI splint in patients with Chronic Migraine.

Method: A placebo controlled, single-blinded cross-over study was done with IRB oversight assessing the efficacy of the NTI splint compared to placebo using the change in the HIT-6 score as the outcome measure.

Results: 68% of refractory chronic migraine sufferers using the NTI as measured by sequential HIT 6 scores had at least a one-category improvement (severe to substantial, or substantial to some, or some to none) compared to 12% when using a placebo device. 36% of subjects using the NTI device reported a two-category improvement in their HIT-6 score, compared to 0% when using placebo.

Conclusion: The improvement in HIT-6 scores produced by the NTI device, suggests that patients with Chronic Migraine may have intense nocturnal jaw clenching as a contributing factor to their headache related disability. An NTI device is one method of assessing whether jaw-clenching is a contributing factor to ongoing migraine.

Trial registration: Current Controlled Trials NCT04871581. 04/05/2021. Retrospectively registered.

Keywords: Clenching; HIT-6 score; Migraine; NTI Splint; Nociceptive.

Conflict of interest statement

The author declares that he has no competing interests.

© 2022. The Author(s).

Figures

Fig. 1

NTI device. 1) Initial closure. 2) Lower device 3) protrusive position. 4) retrusive position. The device must be modified to ensure incisor edge contact in the extremes of each position

Fig. 2

Placebo device. 1. No device. 2. Warmed thermoplastic in place 3. Cooled thermoplastic. 4. Final placebo device. 5. Placebo in place

Fig. 3

Opposing NTI devices to provide for minimal lateral resistance. The greater the surface area of contact, the more intense the clenching activity can be, therefore, the contacting surface area should be minimized

Fig. 4

Improper NTI Protocol. Arrows indicate canine contact on the NTI device when the patient’s jaw shifts laterally. Canine contact allows for intense trigeminal motor hyperactivity (clenching), creating considerable strain to the contralateral temporomandibular joint, potentially producing excessive nociception

Fig. 5

Corrected NTI protocol. By maintaining incisor edge contact and preventing canine or posterior tooth contact during the parafunctional acts, the properly-aligned NTI keeps both the muscle contraction intensity and strain on the distracted temporomandibular joint to a minimum

Fig. 6

Temporalis EMG of Maximum Clenching Intensity over the anterior left and right temporalis muscle (TA-L and TA-R)

Fig. 7

Comparison of effect of NTI vs Placebo on degree of negative impact of Chronic Migraine on individual subjects

Fig. 8

Reduction in categories of negative impact

Fig. 9

Crossover comparisons of the 19 subjects who completed the trial, changes in HIT-6 scores for each group. (a HIT-6 score of ≤ 49 equates to no impact on the subject’s life (percent changes are therefore relative to a score of 49)

Fig. 10

Percent reduction of listed symptoms during second month of NTI use compared to Control Device in the initial FDA trial study

Fig. 11

Percent reduction of migraine events of individual full-coverage control splint users (Elkhart site) during second month of use in the initial FDA trial study

Fig. 12

Percent reduction of migraine events for individual NTI users (Elkhart site) during second month of use in the initial FDA trial study