Incorrect teething sequence is mainly an abnormal order of eruption of permanent teeth. It can be caused by stagnation of milk teeth, insufficient space for tooth eruption and periapical infection of milk teeth. 1. Retained milk teeth: During the period of milk teeth, if the periapical infection causes the root of milk teeth to adhere to the alveolar bone or the root resorption of milk teeth is abnormal, it can lead to the retention of milk teeth. Retained milk teeth can prevent the permanent teeth below them from erupting, and eventually late eruption occurs. This can be accomplished by removing the retained milk teeth to facilitate the eruption of permanent teeth. 2. Insufficient eruption space: After early loss of milk teeth or permanent teeth, the teeth may move or tilt towards the gap, resulting in insufficient space for permanent teeth to erupt, causing them to erupt late. This can be prevented by using a gap retainer and leaving enough space for the eruption of permanent teeth by means of orthodontics. 3. Periapical infection of milk teeth: This disease can cause damage to the embryonic follicles and alveolar bone of the permanent teeth underneath them, causing the permanent teeth underneath them to erupt prematurely. Permanent teeth erupt too early, the roots have not yet formed or only formed a small part, it is easy to fall off due to injury or infection. In this case, an eruption stopper can be used to prevent eruption, and regular observation can follow. Late or early eruption of permanent teeth can lead to abnormal eruption sequence and should be prevented. When an abnormal eruption sequence occurs, consult your dentist to determine if treatment is necessary.