A frenum (or frenulum) is a small fold of tissue that secures or restricts the motion of a mobile organ in the body. The primary function of oral frenula is to keep the lips and tongue in harmony with the growing bones of the mouth during development. The frenums of most concern are those found under the tongue, front upper lip, and front lower lip.
Tissue irritations or ulcers related to frenums are 'caused' when the tissue comes into contact with the appliance, i.e. aligner, or is traumatized, like with a toothbrush.
Some frenums are larger than others; some have abnormal attachment locations. For example, if a patient is "tongue tied" then they have an unusually short, thick lingual frenum, connecting the underside of the tongue to the floor of the mouth.
For the more extreme frenum problems, a simple "snipping" or cutting of the frenum is performed.
These can be difficult to detect because the aligner may feel comfortable at first, but as the patient speaks and moves around, the frenum becomes irritated and ulcerated. Unfortunately this dynamic movement is not captured in the impression. Clear photographs can help to identify these. Gingival frenum pulls are rare, but when they occur, they are typically found in the maxillary premolar and midline areas. If this proves to be a problem, you may want to trim the aligner shorter in the affected areas.