You're probably thinking of an NTI-tss, made by Dr. Jim Boyd. See
DrJimBoyd.com and the related link, HeadachePrevention.com. On the
Headache page is a link to find dentist near you who are trained to
create an NTI for you.

Hello--

I have a jaw that pops occasionally on one side.  I can go months
without it popping, but once it starts it will pop three or four times
a week and then go away again in a couple weeks.  It's frequently
started by an extended dentist visit -- and I've had several of those
this year with having an implant done.

I also have tori (spelling?) where the bone ridges are growing on the
outside of my upper jaw and on the inside of my lower jaw.  I clench my
jaws when I sleep apparently, but do not grind.  I think it is stress
related.

At one point my dentist did a molded night guard for me that was just
one of those clear flexible things.  It had a sharp ridge across the
roof of my mouth and was uncomfortable when my tongue hit it -- and it
was right where my tongue went.  So what would happen is that my tongue
would apparently push at the back of my front teeth and when i'd wake
up in the morning, my bite was different and my teeth would shift back
during the day and start all over again.

When I started to explain to my dentist, I didn't even get the first
couple sentences out before he told me that what I really needed was
extensive work to realign my jaws because dentists now know that
clenching isn't caused by stress but by improperly aligned jaws and he
cited my occasional popping as proof.  He said that things like braces,
possible crowns, and possibly bone work might be necessary to perfectly
align jaws and it could cost $20,000 - $30,000.  I just don't have that
kind of money to spend right now and it wouldn't be covered by
insurance.

Recently, I have read about a different kind of bite guard, though that
is something only your front teeth bite down on.  I cannot remember the
name of that kind of guard.  Before that I hadn't known that different
kinds were available.  What kind might be best to prevent me from
clenching and causing the bone ridges to get even bigger?

Thanks!