The protruding mouth, or bimaxillary prognathism, refers to a prominently projecting mouth that blunts the natual contouring of the lower third of the face. The condition is more common in people of Asian descent.
Ideally, the tip of the nose projects farther out from the face than any other element. With a protruding mouth, the lips may not only compete with the nose in side profile but sometimes surpass it.
With a protruding mouth, the lips often stay open when the face is at rest and sometimes expose too much of the gums. When closed, they may appear inharmonious with the chin. Attempting to close the mouth completely may cause wrinkling on the chin. The mouth and lips may feel dried out upon awakening in the morning.
The lips are usually large and thick and too much gum tissue may be visible when smiling. The space between the base of nose and top of the upper lip appears too short.
The cause of such appearance has little to do with the soft tissues of the skin and lips and more to do with the underlying bone, usually the maxilla (cheek bone) but sometimes also the mandible (jaw bone).
If the degree of protrusion is mild, it may helped by tooth extraction followed by prolonged orthodontic treatments. However, if the gums are protruded as well as the teeth and the amount of protrusion is than 4 mm, surgery is generally indicated.
Cutting cheek bone (black lines), \
removal of bone and tooth (red),
followed by repositioning of remaining
teeth and bone backwards
Surgical correction requires extensive preoperative analysis and planning. Some teeth may be removed, after which the remaining teeth and gums are moved backwards.
Doing so requires an incision made along the gums, fracturing of the upper jaw bone (maxilla) alone if mild, or both jaws bones (maxilla and mandible; known as "double jaw surgery") if more severe, removal of cut bone and/or teeth, surgical repositioning and fixation of each jaw bone, and finally wiring.
Orthodontia with braces may be required for a year after surgery, although sometimes use of a simpler dental prosthesis is adequate.