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The word prognathism derives from Greek pro (forward) and ganathos (jaw). Strictly speaking, the word refers to a faciocranial structure where the either the maxillary (upper) dental arch, or the mandibular (lower) dental arch, protrudes beyond the plane of the forehead. Alveolar prognathism is a protrusion of that portion of the maxilla where the teeth are located, in the dental lining of the upper jaw. Prognathism also can be used to describe ways that the maxillary and mandibular dental arches can relate to one another. Orthodontists often refer to this type of maxillofacial relationship as Skeletal Class III. When there is maxillary prognathism, the condition is called an overbite. When the lower jaw extends beyond the upper, the condition commonly is called an underbite.

The vast majority of prognathism in humans is due to normal variation among phenotypes. In human populations where prognathism is not the norm, it may be a malformation, the result of injury, a disease state or a hereditary condition.

Use in forensic science and anthropology

Humankind historically has been grouped into racial categories based on sets of phenotypical characteristics. While the concept of race has fallen into disfavor, certain clusters of phenotypical characteristics historically assigned to closely related human populations remain useful today in various archaeological and forensic disciplines. The degree to which prognathism is, or is not, present commonly is used today to help establish the relatedness of human populations, living and dead; their likely geographic origins; and, still, to assign racial classification. It is also one of many commonly utilized metrics in the identification of human remains, including in the field of forensic reconstruction.

Broadly speaking, prognathism is most common among Negroid, Australoid and Capoid, peoples whose ancestors were indigenous to Africa (except for Maghreb Berbers); Australoid peoples of Australia, New Guinea, various Malaysian populations and peoples of the Indian subcontinent. Alveolar prognathism a forward projection of the dental lining, that portion of the maxilla where the teeth are rooted. Alveolar, as well as maxillary and mandibular prognathism are more common in these populations. Caucasoid peoples, generally considered indigenous to Europe and nearby regions, commonly have an orthognathous, or flat profile, with Mongoloids, or those indigenous to Asia, generally having prognathism to a moderate degree. There are, however, frequent exceptions to these broad categories, which defy narrow racial and/or ethnic classifications.

Scientific racism and white supremacy

A number of anthropologists of the nineteenth century believed that a classification into strict racial categories and the social development of peoples could be determined by measuring the facial angle, jaw structure and the shape of the human head. Further, they and asserted that people possessing the phenotypical characteristics associated with white Caucasoids, among them being a more orthognathous profile, were inherently superior to people with differing physical characteristics, because whites were more highly evolved than other races.

After Darwin popularized the idea that humans are descended from apes, the prognathous (protruding) jaw became a sign of lower development and of a closer relationship to primitive man. It also became the basis of much racial stereotyping of the Irish, and racial anthropologists argued that working class people were more prognathous than their social superiors- who were- self-flatteringly described as also biologically superior. In his very influential book, The Races of Man (1862), John Beddoe, the future president of the Anthropological Institute, emphasized the vast difference between the prognathous (protruding) and orthognathous (less prominent) jawed people of Britain. These were terms originally The Irish, Welsh, and significantly, the lower class people, were among the prognathous, whereas all men of genius were orthognathous. (Beddoe also developed an Index of Nigressence, from which he argued that the Irish were close to Cro-Magnon man and thus had links with the "Africinoid" races!) These activities were reminiscent of Pieter Camper's theory of a 'facial angle'. One should emphasize, however, that such craniological and anthropometric studies "always represented a minority" of the papers presented at the Anthropological Institute, 1871-1899. These late nineteenth-century anatomical and anthropological descriptions of 'races' and their characteristics, measurements etc. were later the inspiration for the sort of mid twentieth-century racial anthropology as promulgated in Nazi Germany. (Anthony S. Wohl )

Abnormal manifestations

Prognathism
Specialty	Orthodontics

Prognathism in all its kinds can be a hereditary condition which develops during growth or may be, more seldomly, the result of injury or disease.. It exists to varying degrees and takes different forms.

Alveolar prognathism

An alveolar prognathism is limited to the dento-alveolar region of the jaw. It can be limited to one jaw or to both of them (biprotrusion). In these cases the front teeth are inclined forward. Alveolar prognathism can be combined to maxillary or mandibular prognathism.

Harmful habits, such as thumb sucking or tongue thrusting can result in or exaggerate an alveolar prognathism, causing teeth to misalign. Functional appliances can be used in growing children to help modify bad habits and neuro-muscular function, with the aim of correcting this condition.

Alveolar prognathism can be easily corrected also with fixed orthodontic therapy. However, relapse is quite common, unless the cause is removed or a long term retention is used.

Maxillary prognathism

Maxillary prognathism is a protrusion of the maxilla and, as noted above, is also a common feature of many human populations. It affects a large area of the face, causing it to jut out, thereby increasing the facial area. In disease states, it is associated with de Lange Syndrome. False maxillary prognathism, where there is a lack of growth of the mandible, is by far a more common malformation.

Abnormal prognathism, if not extremely severe, can be treated in growing patients with orthodontic functional or orthopaedic appliances. In adult patients, this condition can be corrected by means of a combined surgical/orthodontic treatment, in most cases, a mandibular advancement.

Mandibular prognathism (Progenism)

Pathologic mandibular prognathism is a disfiguring, genetic disorder where the lower jaw outgrows the upper, resulting in an extended chin.

The condition is colloquially referred to as Habsburg jaw, Habsburg lip or Austrian Lip (see Habsburg) due to its prevalence in that bloodline. The trait is easily traceable in portraits of Habsburg family members. This has provided tools for people interested in studying genetics and pedigree analysis.

It is alleged to have been derived through a female from the princely Polish family of Piasts, its Masovian branch. The deformation of lips is clearly visible on tomb sculptures of Mazovian Piasts in Warsaw and was, perhaps, first observed in Maximilian I (1459-1519).

Traits such as these that were common to royal families are believed to have been passed on and exaggerated over time through royal intermarriage which caused extreme inbreeding. Due to the common custom of politically motivated intermarriage among Habsburgs, the dynasty was virtually unparalleled in the degree of its inbreeding. Charles II of Spain is said to have had the most pronounced case of the Habsburg jaw on record. His jaw was so deformed that he was unable to chew.

Many dog breeds have underbite, particularly those with short faces. These can get caught in their jowls.

Notable people with abnormal mandibular prognathism

• Charles II of Spain suffered from the condition and was unable to chew as a result.
• Charles V, Holy Roman Emperor (Charles I of Spain)
• Bill Cowher
• Cymburgis of Masovia, Piast princess through whom the condition was brought into the Habsburg family
• Bruce Forsyth
• Jimmy Hill
• Jay Leno
• Maximilian I, Holy Roman Emperor
• Philip II of Spain
• Philip IV of Spain
• Michael Schumacher

• Dentistry
• House of Habsburg
• Physical anthropology