This is the secret of Taoist health preservation, that is, knocking on the upper and lower teeth every day (at least 100 times a day, which can delay tooth loss for several years or even longer), and swallowing saliva frequently (the method is: the tip of the tongue gently touches the gums, and the middle part of the tongue bulges slightly, so that the saliva secretion speed in the mouth will be accelerated, and then swallowing. In Taoism, there is a famous name called "longevity wine", which seems to be good for gastrointestinal function. My wife's grandfather is an old military doctor. He is 85 years old and hasn't lost a tooth. He loves chicken feet and chews them clean, which makes me feel ashamed (better than my teeth). His old man often says these two words.

Not necessarily accurate, I'll give you a reference.