Children generally change their teeth at the age of 6 ~ 7, and their deciduous teeth gradually fall off and their permanent teeth erupt one after another. Permanent teeth have erupted, but the deciduous teeth in the corresponding position have not yet fallen off, which is called "deciduous teeth retention", also known as deciduous teeth delay.
There is a close relationship between deciduous teeth loss and permanent teeth eruption in children during tooth replacement. Because there is a permanent tooth embryo growing under each deciduous tooth root, the permanent tooth embryo will gradually press the deciduous tooth root in the process of growing and erupting to the oral cavity, and the bone absorption will be thinned through the action of osteoclasts. At the same time, the root cause of deciduous teeth
The oppressed stimulus is gradually absorbed, and the root becomes shorter and shorter until it disappears, so the deciduous teeth loosen, and finally only the crown of the deciduous teeth sticks to the mucosa. At this time, as long as you bite a little hard food, the deciduous teeth will fall off. So we see that deciduous teeth have no roots. There are many deciduous teeth falling off.
You can see the outcrop of permanent teeth.
There are three main reasons for delayed deciduous teeth:
① Malposition of the permanent tooth embryo: that is, it does not grow under the deciduous teeth, resulting in that the permanent teeth and the root of the deciduous teeth cannot contact. Because the root of deciduous teeth can't be oppressed and stimulated by permanent teeth, the root doesn't absorb, so it doesn't loosen on the gums, which leads to the deciduous teeth falling off slowly.
② Peri-root infection secondary to deciduous tooth disease leads to permanent tooth germ necrosis, or the deciduous tooth root and alveolar bone adhere to each other due to inflammation, so that the deciduous tooth root can't be absorbed completely or at all, and the deciduous tooth can't fall off.
③ Tooth germ with congenital absence of permanent teeth: Because the permanent teeth are not developed, the root of deciduous teeth can not be oppressed and stimulated, so it will not be absorbed and will naturally stay on the gums for a long time. Sometimes this kind of residual deciduous teeth still has a certain chewing function in adulthood. Whether deciduous teeth that have not fallen off for a long time need to be pulled out depends on the actual situation. If the X-ray shows that there are no permanent teeth under the deciduous teeth and the deciduous teeth are arranged neatly, it is still ok. Should be retained. If the deciduous teeth occupy space and cause dislocation and eruption of permanent teeth, they should be pulled out. Dislocated permanent teeth should be treated by orthodontics to correct them to their normal positions.
There are four main reasons for delayed eruption of permanent teeth:
(1) Child malnutrition: lack of vitamins A and D, etc. It will cause calcium and phosphorus metabolism disorder in children. When changing teeth, permanent teeth often can't erupt on time.
2 endocrine and metabolic disorders: such as hypothyroidism and dysfunction of the anterior pituitary gland under the hypothalamus directly affect the normal development of various organs of the body, and permanent teeth often fail to erupt on time.
③ Injury of deciduous teeth: the root of deciduous teeth adhered to alveolar bone, which hindered the normal eruption of permanent teeth.
(4) Premature extraction of deciduous teeth: The soft tissue in the missing teeth often rubs against food, which makes the mucous membrane on the gums thicker and tougher, thus increasing the resistance to eruption of permanent teeth, leading to delayed eruption of permanent teeth.
Why does calcium deficiency affect children's tooth eruption?
Calcium deficiency is the most common cause of tooth eruption in children. In the process of tooth construction, calcium deficiency caused by any reason will affect the formation and calcification of tooth germs, leading to poor calcification of teeth, thus slowing down or even stopping the deposition of calcium in teeth and jaws. Excessive consumption of food containing alkaline phosphate and oxalate, such as spinach, will affect the absorption of calcium, because it can combine with calcium to form insoluble compounds. Intestinal peristalsis is fast, and the food stays in the intestine for a short time, which also hinders the absorption of calcium, so children with diarrhea are prone to calcium deficiency. According to the measurement, an adult only needs to absorb 17% calcium from the diet every day, 1 1 ~ 16-year-old children need to absorb 37% calcium from the diet, while nursing babies need it. The younger the age, the higher the demand for calcium, and the easier it is to lack calcium. Human calcium is mainly absorbed in the upper part of small intestine. Vitamin D can not only promote the absorption of calcium in small intestine, but also improve the function of blood calcium and blood phosphorus, which is beneficial to the calcification of bones and teeth. If children are short of calcium and vitamin D, rickets and osteomalacia will occur, leading to tooth and jaw dysplasia, alveolar bone osteoporosis, periodontal tissue lesions and tooth eruption. Therefore, in the process of tooth calcification, many parents think that children's teeth are defective in development, and giving children some calcium tablets is conducive to the good growth of teeth. It is true that the tissues in all parts of teeth are highly calcified substances, and the enamel on the surface of teeth contains 96% inorganic salts, 90% of which are calcium phosphate, so calcium is an important element in the development of teeth. It is beneficial to take enough calcium in the calcification stage of teeth. However, once the teeth erupt, calcification is complete. Eating calcium tablets again won't make your teeth better. Teeth are the organs on which people eat food, and teeth will be further calcified by external influences, but the degree is extremely limited. Calcified teeth can not rebuild the main body through metabolism after eruption. To make children's teeth develop well, they should have diet, nutrition, oral hygiene, strengthen exercise, get more sunshine, get in touch with the air and water in nature, and enhance their physique.