Hi Doctor. My Seventeen Month Old Daughter Just Tripped, And

Hi Doctor. My seventeen month old daughter just tripped, and unfortunately fell on her face. Now her bottom lip has a cut from either her tooth hitting it, or she bit down on it. It was bleeding, and she was crying, but after about five minutes or so, the bleeding stopped. And now she seems to be fine. My question is, how do I know if stitches are needed? I don't know if they're really necessary or not. Thank you so much for your help!