Crooked teeth can be treated by removing some of the teeth and orthodontics. The main cause of crooked teeth is crowding. 1. The ectopic eruption of permanent teeth caused by the non-shedding of milk teeth during the period of replacement teeth is common; the lack of physiological stimulation of milk teeth during the period of replacement teeth causes no loosening, and the root of milk teeth is not resorbed, which can be solved by removing part of the milk teeth in time and carrying out orthodontic treatment. 2. The main reason for the teeth misalignment and crookedness in the period of permanent teeth is the lack of bone volume and the lack of space for teeth arrangement caused by too large teeth, which results in the crookedness of the teeth. Some teeth need to be extracted for orthodontic treatment to restore normal tooth alignment. 3. For some of the teeth caused by supernumerary teeth, it is necessary to remove some of the supernumerary teeth for later correction. It is recommended to have the teeth straightened or extracted as soon as possible.