Convexity of the mouth can be determined by soft tissue lateral view and cephalometric analysis, the latter of which requires an orthodontist to analyze and determine, and is more accurate. Convexity of the mouth can be caused by excessive protrusion of the teeth, excessive growth and development of the jaws, concave base of the nose, fuller lips and other factors, and some people can often be accompanied by a gummy smile, lines are more obvious than those of the same age and other symptoms. There are two ways to determine this. 1. Soft tissue side view observation method: mainly connecting the tip of the nose and the point in front of the chin to form a straight line, i.e., the E line, if the lips are located in front of this line, then it can be initially judged as a convex face type, but this method is more rough, and it needs to be further diagnosed by the orthodontist. 2. Cephalometric analysis method: measurements are made after taking lateral cephalometric films, in which the increased SNA or SNB angle represents the corresponding maxillary or mandibular protrusion, and maxillary protrusion or both maxillary and mandibular protrusion often lead to bony convexity; the maxillary or maxillary mandibular incisors have a larger labial inclination, which often leads to dental convexity; the facial angle and nasolabial angle are smaller than the normal minimum value, which also often manifests a convex face type. If you have a convex mouth, you need to consult a professional orthodontist and improve your oral examination and imaging examination, so that you can make the correct diagnosis and treatment.