It's inconclusive that a surgical procedure called lingual frenotomy (also referred to as frenulotomy, frenulectomy or frenectomy) can slightly lengthen one's tongue, according to Caroline Bowen, PhD. There are many claims that a minor lengthening of the tongue occurs as a result of the process, but are not substantiated by medical evidence.
Lingual frenotomy allows for fuller tongue extension and freedom of movement, as concluded by Aetna.
The procedure, a process wherein a membrane under the tongue is clipped in order to free it from constriction, is intended for patients who were born with a shortened lingual frenum, according to WebMD. The frenum is the thin, vertical fold of tissue that connects the underside of the tongue to the floor of the mouth. When the frenum is too short, the patient may experience ankyloglossia (tongue-tie), or an inability to pronounce certain words. The condition presents itself at birth, and results in limited movement or extension of the tongue. In infants, it inhibits the ability to latch onto it's mother's breast and feed normally.
In cases of ankyloglossia, it's common for the tongue to be unable to protrude past the upper or lower incisors, as described by speech and language pathologist, Carolyn Bowen, PhD. She further explains that it rarely impairs speech and may correct itself over time.