I am yet to see or heard about any great yogi who got enlightenment or something near to that by cutting the frenum under the tongue. But I know many yogis who can touch the uvula with the tip of the tongue. Many great yogis have different views on Kechari Mudra. Touching the third eye is one end of the Kechari Mudra story. Thre are many other stories. People are often confused. The basic question is what is achieved by these exercise? Of course, the first answer is bliss. However, just turning the tongue backward and meditation on the tip of the tongue is having several other benefits.
According to Paramhansa Yogananda one of the benefits of practicing Khechari Mudra is “It draws energy from the cerebrum and medulla by connecting the tip of the big tongue with the little tongue (uvula).” Again he said “Right attitude, devotion, and attunement to the Guru are more important than an over-reliance on exotic techniques such as Khechari Mudra.”
In the book “Yoga and Vipassana: An Integrated Life Style” Sri Amit Ray of Himalaya, Uttarkashi brilliantly explained “I have seen several yogis buttering, massaging and pulling their tongue in the morning and in the evening. Definitely, these practices helped them to keep their attention on the tongue area. There are many sensitive invisible micro astral nerves on the palates and on the tongues. Physically, numerous taste cells are positioned not only on the tongue but also on the uvula, soft palate, larynx, pharynx, and epiglottis. This type of tongue massaging activates those taste buds on the tongue, and stimulates the secretion of certain endorphin like hormones. This produces some bliss energy in the third eye area. That is definitely a good incentive for a new yoga student. But that temporary bliss is not the objective of a true yogi. Even to get that great bliss energy you don’t need to cut the frenum under the tongue. With the help of some herbs and mantra kriya practices on the tongue you can get much better result. It is foolishness to cut the frenum under the tongue.
Kechari Mudra is much more than that. It is a great mystery. It is the mystery of exploring the inner vastness. It is merging into the nectar of inner and outer vastness. The role of physical exercise is very limited. Discovering the micro astral nerves on the palates and the uvula is the first challenge. For that you need to focus your one pointed awareness and attention in the area of ….”
Before proceeding to true Khechari Mudra, you need to do other practices to prepare the body and mind. It needs purification. It needs the practice of Sila, Samadhia and Panna. Just cuting the frenum and turning the tongue backwards and touching the palate is not enough.
When our mind will be pure and heart is full of love Kechari Mudra will occur spontaneously. Our mental purification is more important than tough physical exercise.