If the baby teeth in the lower incisors do not fall out and new teeth grow out of them, it may be caused by stagnant baby teeth or supernumerary teeth, etc. Depending on the situation, you can choose temporary observation, dietary modification, extraction of baby teeth and orthodontic treatment. 1. Temporary observation: Under normal circumstances, the permanent teeth start to grow on the lingual side of the milk teeth and gradually erupt, the roots of the milk teeth are gradually absorbed, and the milk teeth will become loose and fall out, etc., which can be observed for the time being. You can observe for a while. Eat more hard food to promote root resorption and eruption of milk teeth, so as to avoid misalignment of permanent teeth. 2. Remove the milk teeth: the milk teeth have not fallen out or loosened, and the new teeth inside have exceeded 1/2 of the height of the milk teeth, then it is best to remove the loosened milk teeth. If necessary, orthodontic treatment can be performed as prescribed by the doctor. 3. Extraction of supernumerary teeth: If the lower incisors are not lost and new teeth grow from inside, they may be supernumerary teeth, which need to be extracted in time to avoid affecting the eruption of permanent teeth. If your lower incisors are not falling out and new teeth are coming in, you should go to the hospital in time and choose the best treatment plan according to the examination results.