Teeth lengthening may be caused by wrong way of brushing, gum recession, missing teeth and tumor. 1. Wrong way of brushing: It may be that the patient often uses hard bristle toothbrush, rubs the gums hard or brushes horizontally horizontally, which can stimulate the gums to shrink and make the crowns of the teeth longer. 2. Gum recession: a large accumulation of plaque and calculus around the gums can lead to a large number of bacterial growth to stimulate the gums, triggering inflammation and causing gum recession. In fact, the teeth did not get longer, just gum recession, the gums below the teeth exposed, giving people an illusion, feel the teeth longer. 3. Missing teeth: when the teeth are missing for a long time, there is no corresponding biting force for the teeth. With the daily chewing movement and the reconstruction of alveolar bone, the teeth will continue to elongate because there is no obstruction. 4. Tumor: When there is a tumor in the jawbone, the alveolar bone may be resorbed, and the tooth lacks the alveolar bone encirclement, showing loose elongation. Teeth elongation may be a dental problem, and it is recommended that patients go to the hospital to clarify the cause of the disease, pay attention to oral hygiene in life, and protect the teeth.