The old man's tusks indicate future generations.

Embedded teeth and impacted teeth: The third molar and canine teeth (tiger teeth), which are called "wisdom teeth", are often occupied by other teeth because of their late eruption, so they cannot grow smoothly and are buried in the bone. Some people don't erupt until part or all of their old teeth fall off, so they are easily mistaken for new teeth.

2

Extra teeth (also called supernumerary teeth): refers to people who have more teeth than normal people, and their shapes are often similar to those of a group of teeth, but slightly smaller. Extra teeth usually erupt at normal times, but they may be buried in the jaw until they are expected to fall out in old age.

three

Some old people have normal number of original teeth, and most or all of them grow new teeth with normal size after falling off. This situation is extremely rare, and its mechanism is still unclear, which needs further study.