* Prognathism
The word Prognathism derives from Greek pro (forward) and gnathos (jaw).
Is a term used to describe the positional relationship of the mandible and/or maxilla to the skeletal base where either of the jaws.

* Retrognathism
Retrognathism (or retrognathia) is a type of malocclusion which refers to a mandible which is further posterior than would be expected.

prognathism and Retrognathism is the result of injury or a disease state or a hereditary condition. Prognathism and Retrognathismis considered a disorder only if it affects mastication, speech or social function.