Its called a frenulum.
It is the little piece of tissue that connects your lip to your gums.
Its also the little piece of tissue that connects your
tongue to the floor of your mouth.
Why is it important to know what this little piece of tissue is?
Because in certain instances this tissue isn't formed just right and
you may need a procedure done on it called a frenectomy.
That is where the doctor will cut the little piece of tissue in half.
This frees the lip or tongue from being too tightly attached to
whatever is on the other end of the frenulum.
If your dentist hasn't mentioned it in the past then you are probably
okay, but its always a good to check next time you are in.
And there is always the option of piercing your frenulum.
But.... I'm not a big fan of that.