(email from an NTI user):
"I made an NTI for this young lady in October and at her 2 wk check, she was
thrilled to death. Headaches almost 100% gone!
Today, she comes in with this extreme wear. I have never seen an NTI wear
this much and her headaches have returned.
What to do next?"

Some patients' parafunctional activity will wear a divot into the DE.  As their vertical dimension decreases, one of two circumstances may occur: 
-clenching intensity increases, and/or; 
-a posterior contact is able to occur, thereby allowing clenching intensity to increase.

The remedy is to fill and polish the divot back to the original contour of the DE, and not to grind the DE down to the depth of the divot.

In the event the patient wears a divot into the DE with considerable frequency, a "slidebar" can be made on the opposing incisors with the Universal device. (the above example,  the DE has been reduced to close the vertical as much as possible).