There are many reasons for chin up and teeth tilted inward, such as genetic factors, jaw protrusion and so on. 1. Genetic factors: chin up lower teeth tilted inward may be hereditary, if the parents or the family has this phenomenon, then the children may also have this phenomenon. 2. Jaw protrusion: Normal lower teeth should be tilted to the outside, if the jaw protrudes forward, it may lead to the lower lip to press the lower teeth, so it will cause the phenomenon of chin up lower teeth tilted inward. There are many reasons why the lower teeth are tilted inward, it is recommended to go to the hospital in time to improve the examination, and then determine whether it is possible to take orthodontic treatment.