It might be like what happens to your legs from socks with tight bands.
They leave quite an indentation in the legs which takes hours to disappear.

Some nights you might clamp your jaw more, so the tissue between the
teeth and the bone gets compressed the same way. Then the teeth can be
closer together for a while.

Try a change of lifestyle, diet, or perhaps something which might
interrupt the clenching at night, such as a mouthguard.

When it is said that teeth 'elongate' it does not mean that they expand,
just that they rise a little in the gums, isn't it?

O my Balaclava,
I wear it at night,
not too tight,
so warm blood flows in my veins,
easing away pains.
Ears get all warm                    * -^- *
and jaw muscles their proper      /<<<<<>>>>>>\
Neck goes unstiff                |>>>>>>><<<<<<<
and less do I sniff.             | ##~ []] ~## |
Eyes open clear,                  ** 0 ]][ 0 **
and it isn't too dear,             ***********
and all that palaver:                *#####*
bank jobs etcetera;                     *
make it distinctive for the camera.
And if you don't like wool,
or want a little more cool,
make one from cotton,
just a little hott'n.

[It also can protect the eyes from stray light at night - the light
reduces melatonin as well as the mag fields at night?]

Brian Sandle