Prognathism: MedlinePlus Medical Encyclopedia

P Prognathism is an extension or bulging out (protrusion) of the lower jaw (mandible). It occurs when the teeth are not properly aligned due to the shape of the face bones.

T Considerations
P Prognathism may cause malocclusion (misalignment of the biting surfaces of the upper and lower teeth). It can give a person an angry, or fighter's appearance. Prognathism may be a symptom of other syndromes or conditions.

T Causes
P An extended (protruding) jaw can be part of a person's normal face shape that is present at birth.
P It can also be caused by inherited conditions, such as Crouzon syndrome or basal cell nevus syndrome.
P It may develop over time in children or adults as the result of conditions such as gigantism or acromegaly.

T When to Contact a Medical Professional
P A dentist or orthodontist may be able to treat abnormal alignment of the jaw and teeth. Your primary health care provider should also be involved to check for underlying medical disorders that can be associated with prognathism.
P Call a provider if:
- You have difficulty talking, biting, or chewing related to the abnormal jaw alignment.
- You have concerns about jaw alignment.

T What to Expect at Your Office Visit
P The provider will perform a physical exam and ask questions regarding your medical history. Questions may include:
- Is there any family history of an unusual jaw shape?
- Is there difficulty talking, biting, or chewing?
- What other symptoms do you have?
P Diagnostic tests may include:
- Skull x-ray
- Dental x-rays
- Imprints of the bite (a plaster mold is made of the teeth)
P This condition may be treated with surgery. An oral surgeon, plastic facial surgeon, or ENT specialist may perform this surgery.

T Alternative Names
P Extended chin

T Images
- Prognathism

T References
P Taub DI, Jacobs JMS, Jacobs JS. Anthropometry, cephalometry, and orthognathic surgery. In: Neligan PC, ed. Plastic Surgery. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 16.
P Whyte MP. Hereditary disorders of the skeleton. In: Jameson JL, De Groot LJ, de Kretser DM, Giudice LC, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 68.

T Review Date 2/22/2016
P Updated by: Michael Kapner, DDS, general and aesthetic dentistry, Norwalk Medical Center, Norwalk, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M.

