Upper lip protrusion can be hereditary, or it can be caused by acquired factors. Upper lip protrusion is usually caused by maxillary protrusion. If the parents are maxillary protruding, it will be more likely that the child will also be maxillary protruding, but it is not a certainty that the child will develop maxillary protrusion. Maxillary protrusion can be caused by the anterior maxillary teeth protruding forward, or it can be caused by the maxilla protruding too far forward or the mandible retracting too far back. Malformations of the teeth and jaws may be caused by heredity or by acquired habits or diseases. If the protrusion of the upper lip is severe or accompanied by other symptoms, it is recommended to visit a hospital in time to receive targeted treatment after the cause is clarified with the help of a doctor.