It surely can’t be worse for you than not brushing your teeth at all, right?
If you ever find yourself in a situation without toothpaste, then go ahead, brush regardless.
It should help stimulate your gums, strengthening them and remove some of the plaque you’d find on the surface of your teeth.
Of course it won’t be as beneficial as using the abrasives found in most toothpastes but it’s much better than just letting bacteria eat away at all those little delicious bits of carbohydrates, proteins and fats left behind after eating/drinking.
Think of abrasives as sandpaper.
Brushing often leaves your teeth feeling nice and smooth afterwards!
Even without the use of toothpaste, your teeth should feel noticeably more polished.
So if you find yourself without your favorite minty toothpaste, don’t hesitate to brush anyway.