A torn lingual frenulum may be caused by injuries to the mouth or a piercing in the mouth, according to the University of Michigan Health System. Eating something sharp can also cause this.
The lingual frenulum is the flap of skin found under the tongue. The skin connects the tongue to the lower jaw. If the tear is significant, stitches may be used to close or repair the problem. Often, it heals on its own. Some people are born with a thicker than usual lingual frenulum. This is referred to as tongue-tie and can be fixed with surgery, as stated by Mayo Clinic.