Increasing vertical dimension can decrease clenching intensity
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Occasionally, when treating a "primary clenching" patient in the attempt to decrease headache frequency and/or intensity, increasing the vertical dimension may be required.

The EMG recordings above show the effect on temporalis contraction intensity when the "usual and customary" NTI device is delivered (middle).  Although clenching (temporalis intensity) is decreased with the NTI, for some patients, it may not be adequate enough of a reduction to noticeably reduce headache frequency and/or intensity.   By enhancing the Discluding Element by 1 to 2.5 mm or so, clenching intensity may be further reduced and may allow headache frequency and/or intensity to decrease.   Thanks to Barry Glassman for providing EMG recordings

Below is a question (indicated by the >'s) emailed to Dr. Boyd regarding vertical dimension with the NTI:

>If it is good to close the vertical with a patient with TMJ pain,

Thereby keeping translation to a minimum in excursive...

> and if it is true that for migraineurs the vertical should be kept at the vertical of the stock NTI (or increased)

False.  You assume that a "primary clencher"/migraineur will eventually look for a way to beat you (that is, clench excursively) so you *reduce* the DE if necessary to maintain disclusion daylight in all excursive positions.  (one of the worst things that could happen is for a migraineur to suddenly have *real bad* joint pain after the third night of NTI use because the vertical was unnecessarily too open.  They run off the their local TMJ specialist to tell on you who then announces "See, I told you the NTI is dangerous!)
So you increase vertical on a headache/migraine patient as necessary/needed.

> then what do you suggest for a migraineur with TMJ pain?

Start out with ideal protocol (minimal opening, minimal disclusion
daylight) and sneek it open *if you need to*.

-Jim