 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Prognathism" – news ·newspapers ·books ·scholar ·JSTOR(September 2018) (Learn how and when to remove this message) |
| Prognathism | |
|---|---|
| Other names | Habsburg jaw (in the case of mandibular prognathism) |
 | |
| Illustration of different types | |
| Specialty | Orthodontics  |
| Types |
|
| Causes | Multifactorial |
| Treatment | Orthodontics;oral and maxillofacial surgery |
| Frequency |
|
Prognathism is a positional relationship of themandible ormaxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in thecoronal plane of the skull.[clarification needed]
In the case ofmandibular prognathism (never maxillary prognathism), this is often also referred to asHabsburg chin,Habsburg's chin,Habsburg jaw orHabsburg's jaw[2][3] especially when referenced with the context of its prevalence amongst historical members of theHouse of Habsburg.[2]
Mandibular prognathism is typically pathological, whereas maxillary prognathism is often the result of normal human population variation.
Ingeneral dentistry,oral and maxillofacial surgery, and orthodontics, this is assessed clinically or radiographically (cephalometrics). The wordprognathism derives from the Greek πρό (pro, meaning 'forward') and γνάθος (gnáthos, 'jaw'). One or more types of prognathism can result in the common condition ofmalocclusion, in which an individual's topteeth and lower teeth do not align properly.[citation needed]
In humans, non-pathological maxillary and alveolar prognathism can occur due to normal variation amongphenotypes.
However, mandibular prognathism is usually anomalous, and it may be a malformation, the result of injury, a disease state, or a hereditary condition.[4]
Prognathism is considered a disorder only if it affectschewing,speech or social function as a byproduct of severely affected aesthetics of the face.[citation needed]
Clinical determinants include soft tissue analysis where the clinician assesses nasolabial angle, the relationship of the soft tissue portion of the chin to the nose, and the relationship between the upper and lower lips; also used is dental arch relationship assessment such asAngle's classification.[citation needed]
Cephalometric analysis is the most accurate way of determining all types of prognathism, as it includes assessments of skeletal base, occlusal plane angulation, facial height, soft tissue assessment and anterior dental angulation. Various calculations and assessments of the information in a cephalometric radiograph allow the clinician to objectively determine dental and skeletal relationships and determine a treatment plan.[citation needed]
Prognathism should not be confused withmicrognathism, although combinations of both are found.
Alveolar prognathism is a protrusion of that portion of the maxilla where the teeth are located, in the dental lining of the upper jaw.[citation needed]
Maxillary prognathism affects the middle third of the face, causing the maxilla to jut out, thereby increasing the facial area.
Mandibular prognathism is a protrusion of the mandible, affecting the lower third of the face.
Prognathism can also be used to describe ways that the maxillary and mandibular dental arches relate to one another, including malocclusion (where the upper and lower teeth do not align). When there is maxillary or alveolar prognathism which causes an alignment of the maxillary incisors significantly anterior to the lower teeth, the condition is called anoverjet. When the reverse is the case, and the lower jaw extends forward beyond the upper, the condition is referred to asunderbite (reverse overjet).[citation needed]
Not all alveolar prognathism is anomalous, and significant differences can be observed among different ethnicities.[5]
Harmful habits such asthumb sucking ortongue thrusting can result in or exaggerate an alveolar prognathism, causing teeth to misalign.[6] Functional appliances can be used in growing children to help modify bad habits and neuro-muscular function, with the aim of correcting this condition.[6]
Alveolar prognathism can also easily be corrected with fixed orthodontic therapy. However, relapse is quite common, unless the cause is removed or a long-term retention is used.[7]
In disease states, maxillary prognathism is associated withCornelia de Lange syndrome;[8] however, so-called false maxillary prognathism, or more accurately,retrognathism, where there is a lack of growth of the mandible, is by far a more common condition.[citation needed]
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, where most of the time a mandibular advancement is performed. The same can be said for mandibular prognathism.[citation needed]
On average, Neanderthals were far more prognathic than modern humans regarding the maxilla. This maxillary prognathism, along with their wide noses, suggests that their faces were not adapted to cold climate.[9]
Mandibular prognathism is a potentially disfiguring genetic disorder where the lowerjaw outgrows the upper, resulting in an extendedchin and acrossbite. In both humans and animals, it can be the result ofinbreeding.[10]
Unlike alveolar or maxillary prognathism, which are common traits in some populations, mandibular prognathism is typically pathological. However, it is more common among East Asian populations but overall, the condition is polygenic.[11]
In brachycephalic or flat-faced dogs, likeshih tzus andboxers, it can lead to problems such as underbite.[12]
In humans, it results in a condition sometimes calledlantern jaw, reportedly derived from the shape of earlylanterns.[a] Traits such as these were often exaggerated by inbreeding, and can be traced within specific families.[10][14]
Although more common than appreciated, the best known historical example isHabsburg jaw, or Habsburg orAustrian lip, due to its prevalence in members of theHouse of Habsburg, which can be traced in their portraits.[15] The process of portrait-mapping has provided tools forgeneticists andpedigree analysis; most instances are consideredpolygenic,[16] but a number of researchers believe that this trait is transmitted through an autosomal recessive type of inheritance.[17][15]
Allegedly introduced into the family by amember of thePiast dynasty, it is clearly visible on family tomb sculptures inSt. John's Cathedral, Warsaw. A high propensity for politically motivated intermarriage among Habsburgs meant the dynasty was virtually unparalleled in the degree of its inbreeding.Charles II of Spain, who lived 1661 to 1700, is said to have had the most pronounced case of the Habsburg jaw on record,[18] due to the high number ofconsanguineous marriages in the dynasty preceding his birth.[17][15]
_(died_1477).jpg)
Prior to the development of modern dentistry, there was no treatment for this condition; those who had it simply endured it. Today, the most common treatment for mandibular prognathism is a combination oforthodontics andorthognathic surgery. The orthodontics can involvebraces, removal of teeth, or amouthguard.[19]
Inentomology, prognathous means that the mouthparts face forwards, being at the front of the head, rather than facing downwards as in some insects.[20]
The dictionary definition ofprognathism at Wiktionary.JPG)