Japanese food is soft, such as rice and natto, which hardly needs to be bitten or torn. Lotus root and American ginseng are hard foods, so the dishes are stewed thoroughly. If you only eat soft food, your teeth will lack good exercise. When children chew bones, their gums are strongly squeezed. This kind of squeezing is a benign stimulus to the gums, which can force the gums to grow fully, and the teeth will grow neatly after tooth replacement.
China's teeth are like a sharp knife, because they often chew bones, while Japanese teeth are like a rusty knife, because they don't bite bones. No matter what its texture is, it can't work normally. Generally speaking, the root cause is that compared with other countries, Japanese people eat relatively soft food, which directly leads to Japanese people chewing less. From a medical point of view, chewing hard objects will cause the gums to be strongly squeezed. This kind of squeezing is a kind of stimulation to the gums, which can force the gums to open completely and the neat teeth will grow out.
Actually, you don't have to chew hard. Like Europeans and Americans, more people like chewing gum. On the one hand, they think that chewing gum can exercise a good-looking chin, especially for men. On the other hand, they unconsciously exercise their teeth and jaws to make them more developed. Japanese women don't want a developed chin, so the Japanese chin is smaller than before, but the teeth are irregular.
The teeth are irregular, the brushing effect drops sharply, many places can't be brushed, and the tooth decay is also very serious, which leads to the Japanese losing their teeth. Orthodontics in Japan is quite expensive, and it takes a lot of effort to train dentists. It takes six years to study dentistry. It is relatively difficult for Japanese to correct their teeth because most people have small maxilla and large mandibular plane angle. The bones of orientals are harder than those of westerners. These factors make it more difficult to correct teeth. Due to the long adjustment period and great economic pressure, they had to give up.