Deep overjaw does not usually result in a square face, and a square face shape may be due to occlusal factors, fat factors, and genetic factors. Deep overjet is a type of malocclusion caused by abnormalities in tooth alignment or jaw development, which is characterized by the incisal edges of the maxillary incisors covering more than 1/3 of the crowns of the mandibular incisors. Deep overjet affects the appearance of the dental arch and the anterior part of the jaw, and is not usually the cause of a square face. Factors that can affect the appearance of a square face include poor chewing habits that cause the bite muscles to develop, or the accumulation of fat in the face that causes the face to become square, as well as hereditary factors, such as a higher likelihood of having square-faced children if their parents are square-faced. If the symptoms of deep overjaw are serious or accompanied by other symptoms, the patient should go to the hospital in time for targeted treatment with the help of the doctor.