"between" the teeth?
'Between my teeth' may refer to two teeth (canine and molar, bit of celery stuck) or 'between my teeth' may refer to 'between two sets of teeth' (my upper set of teeth and my lower set of teeth, and I am biting on a large steak).
In both cases there are only two items in view : two individual teeth, or two sets of teeth.
To say 'among my teeth' means someone has punched me and knocked them all out and I am on my hands and knees, searching for my car keys among my teeth, so I can drive to the Hospital.