There is usually no automatic loss of permanent teeth in 6 year old children after replacement. There are only two sets of teeth in a person’s life, milk teeth and permanent teeth. Milk teeth exist to fall out naturally, but permanent teeth usually do not fall out automatically after they are replaced. If the permanent teeth are lost, there will be no replacement teeth, which means that no new teeth will grow. If you lose your permanent teeth, you may have dental caries or periodontitis. 1. periodontitis: a bacterial infection, severe inflammation of the periodontal tissues will cause alveolar bone resorption and gum recession, resulting in loose teeth and loss of teeth. 2. Dental caries: dental caries is usually not do a good job of cleaning the teeth, food residues left on the teeth, and then through the oral cavity high temperature catalyst, resulting in dental caries, caused by the loss of teeth. There may be other reasons for 6-year-old children to have automatic loss of permanent teeth after replacement, and they should go to the hospital stomatology department in time to find out the reasons and get treatment as early as possible.