The Bajabo people in Mindanao, off the coast of the Philippines, imitate animals and grind their teeth so sharply that they have the sharpest teeth in the world.

Teeth:

Teeth are the hardest organs in the human body, which not only bear the functions of cutting and chewing, but also play the role of maintaining facial appearance and assisting pronunciation.

Teeth can be divided into incisors, canine teeth, premolars and molars. Each tooth consists of a crown exposed outside the alveolar bone, a root growing in the alveolar bone and a neck between the crown and the root.

The main component of a tooth is dentin, which is surrounded by enamel (at the crown) and cementum (at the root). There is also a periodontal membrane composed of fibers outside the cementum to fix the teeth in the alveolar cavity. There is a dental pulp cavity in the center of the tooth, which is filled with dental pulp and rich in blood vessels and nerves.

People have to grow teeth twice in their lives. The 1 eruption is called deciduous teeth, with 5 teeth on the left and right sides of the upper and lower jaws and 20 teeth * * *, which fully grow from 6 months after birth to about 3 years old. At the age of 6 ~ 7, deciduous teeth begin to fall off. The second eruption is called permanent teeth, with 8 teeth on the left and right sides of the upper jaw and 32 teeth on the upper jaw. At the age of 6 ~ 7, 1 molars erupted and deciduous teeth began to be replaced. At the age of 13 ~ 14, all deciduous teeth were replaced. But the third molar (also known as "wisdom tooth" or "full head tooth") will not grow until about 20 years old.