A tooth (plural teeth) is a small, calcified, whitish structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are covered by gums.
Symptoms can include: 1  A popping sound (or a popping or snapping feeling) at the time of injury can sometimes be heard (or felt) if a ligament is completely torn. 2  Swelling of your knee. 3  Pain in your knee.  Tenderness around your knee on 1  touching. Not being able to use or move your knee normally.
Twisting the knee is a common cause of overstretched or torn ligaments of the knee. The knee may give out suddenly when the ACL is torn and there may be a popping sound upon injury. Symptoms of a torn ACL include knee pain, swelling, stiffness, and bruising.