The World Health Organization (WHO) lists malocclusion as one of the three major oral diseases (the other two being dental caries and periodontal disease). The incidence rate of malocclusion in China is as high as approximately 49%. Archaeological evidence indicates that early humans either had no or very few instances of malocclusion, suggesting that malocclusion developed alongside the evolution of the human race. This fundamental reason lies in the tremendous changes in living environments. During the evolutionary process, ancient forest apes split into two groups: one group continued to live in forests, developing strong teeth, prominent jaws and brow ridges, eventually evolving into gorillas. The other group gradually adapted to life on the ground, transitioning from crawling to upright walking. After becoming bipedal, their body's center of gravity changed, leading to a reduction in jaw size and tooth size, while brain capacity increased, resulting in the facial features of modern humans.
Due to the use of fire, food evolved from raw to cooked, coarse to fine, and hard to soft, causing the chewing organs to weaken in function and gradually degenerate and shrink, with an imbalance in this degeneration. Muscles degenerate fastest, followed by the jawbone, while teeth degenerate slowest, making it difficult for the jawbone to accommodate all the teeth, leading to tooth crowding and malocclusion.
Malocclusion can also be genetically passed from parents to children, meaning children's face shapes resemble those of their parents. A characteristic of this genetic trait is that regressive expressions dominate. For example, if the father has a wide upper dental arch and the mother has a narrow upper dental arch, then the child's upper dental arch will more likely resemble the mother's. Therefore, genetics is also an important factor in the occurrence and development of malocclusion.
Due to environmental changes, variations may appear during the genetic process of malocclusion, resulting in an increasing number of types of malocclusion and diversified forms of expression. Thus, in the long evolutionary history of humanity, malocclusion has gone through a process from non-existence to existence, and its incidence rate has risen from low to high.
In modern society, living standards are continuously improving, and people's demand for oral health care is also gradually increasing. However, many people do not pay enough attention to relevant knowledge, especially lacking understanding about children's growth and development, the replacement rules of deciduous and permanent teeth. Early problems in children, such as bad oral habits and whether tooth replacement is normal, cannot be detected in time. Due to these reasons, there are quite a number of malocclusions in China, which is one of the reasons for the high incidence rate of malocclusion. Therefore, doing a good job in promoting oral hygiene knowledge, achieving early prevention and treatment, is an effective measure to reduce the incidence rate of malocclusion.