Primary teeth can't fall off during tooth changing: it usually lasts for several months from the beginning of root loosening to real falling off, and it falls off when you are not paying attention, such as when eating. However, some teeth are like a tied thread that will never fall out. At this time, the deciduous teeth are delayed in tooth replacement: the teeth begin to loosen from the root to actually fall off, which usually lasts for several months, and fall off when they are not paying attention, such as when eating. However, some teeth are like a tied thread that will never fall out. At this time, it may affect chewing or make children feel unhappy. In this case, you can ask the child to try to turn it around. If the root of a tooth falls off completely, a slight rotation will make it fall off, but it must not be forced, let alone yanked, because if only half of the root falls off, the consequences of forced pulling are easy to cause injury and infection. In addition, if the child is over 7 years old and has not lost his teeth, he should be taken to the hospital for dental examination. General doctors will check whether permanent teeth are embedded in gums or have any developmental problems by taking X-rays. Generally speaking, the delay in changing teeth will not have any big impact on children. On the contrary, some doctors also believe that permanent teeth can be "bred" under the gums for a long time, making them grow strong and break through the "imprisonment" of the gums smoothly. Early deciduous teeth fall off. The average child's first tooth falls off at the age of 5-7. If the teeth fall off before the age of 4, it is usually caused by internal reasons, which may be systemic or just local oral reasons, such as metabolic disorder or periodontal disease. So early treatment is very important. There is pain in the process of tooth loosening and falling off, but as the deciduous teeth begin to fall off, the child's "six-year-old teeth" will grow out, which may cause gum swelling and make the child complain about toothache. In the meantime, the child may complain that he can't chew, but parents should ensure a reasonable and balanced diet. At this time, parents can make some foods that are easy to chew and swallow, such as vegetable soup and broth, to ensure the needs of the body, and encourage him to brush his teeth and clean his mouth. Congestion of deciduous teeth will cause problems in the arrangement of permanent teeth. Generally speaking, the reason for the crowding of permanent teeth is the contradiction between the width of the teeth themselves and the width that the dental arch can provide. Because the size of teeth has been determined long ago, the width of dental arch is generally set before the age of 3, so whether permanent teeth are crowded or not is related to the space between deciduous teeth. But it is not absolute, because the permanent molars that children grow will be smaller than the deciduous molars, which will prepare a little space for other teeth. If necessary, you can use this space to relieve the crowding of front teeth, which depends on the advice of dental plastic surgeons. Experts remind parents, friends and children that a series of problems such as premature or delayed deciduous teeth falling off, pain when changing teeth and dislocation or gap of permanent teeth caused by deciduous teeth should be paid enough attention. Experts suggest that children should pay more attention to the observation of children's oral cavity during tooth replacement, check whether there are abnormal teeth, deal with problems in time, and take their children to a doctor for oral examination every six months if possible.