My 2 year old fell and hit his mouth. he bit the inner of his lips. would he need stitches?

Sometimes: If the cut crosses from the fleshy pink inner tissue over into the outside skin, stitches are sometimes needed to make sure the border of the lip does not heal in a jagged line. If the cut is only in the inner pink tissue they are often left alone. Saliva has anti germ qualities but stitches there can trap germs & get infected easily. I would contact his doc. It may need to be seen to be sure.