The correct term for incisors is incisors. One long and one short incisor may be caused by malocclusion, developmental abnormality, eruption abnormality and so on, as follows. 1. Malocclusion: If one incisor has labial or lingual inclination malocclusion, it can be shorter than normal incisors under direct vision, resulting in one long and one short. 2. Developmental abnormality: If there is enamel underdevelopment or dentin underdevelopment of the incisors, the teeth are prone to abrasion, and the uneven abrasion of the two incisors will lead to one long and one short crown. 3. Eruption abnormality: If one of the incisors is blocked and cannot fully erupt to establish a normal occlusion, it will lead to the incisors being one long and one short. There may be other reasons for the incisors to be short and long, so it is recommended to go to the hospital in time to clarify the cause of the disease and then carry out targeted treatment.