Medicine:Prognathism

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Prognathism is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull.[clarification needed]

In the case of mandibular prognathism (never maxillary prognathism), this is often also referred to as Habsburg chin, Habsburg's chin, Habsburg jaw or Habsburg's jaw[1][2] especially when referenced with the context of its prevalence amongst historical members of the House of Habsburg.[1]

Mandibular prognathism is typically pathological, whereas maxillary prognathism is often the result of normal human population variation.


Presentation

Mandibular prognathism, where teeth have almost reached their final, straight position by dental braces, making the prognathism more obvious

In humans, non-pathological maxillary and alveolar prognathism can occur due to normal variation among phenotypes.

However, mandibular prognathism is usually anomalous, and it may be a malformation, the result of injury, a disease state, or a hereditary condition.[3]



Prognathism should not be confused with micrognathism, although combinations of both are found.


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.


Classification

Alveolar prognathism

Alveolar prognathism, caused by thumb sucking and tongue thrusting in a seven-year-old girl

Not all alveolar prognathism is anomalous, and significant differences can be observed among different ethnicities.[4]

Harmful habits such as thumb sucking or tongue thrusting can result in or exaggerate an alveolar prognathism, causing teeth to misalign.[5] Functional appliances can be used in growing children to help modify bad habits and neuro-muscular function, with the aim of correcting this condition.[5]

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.[6]

Maxillary prognathism

In disease states, maxillary prognathism is associated with Cornelia de Lange syndrome;[7] 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.

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.[8]

Mandibular prognathism (progenism)

Portrait of Leopold I, showing progenism

Mandibular prognathism is a potentially disfiguring genetic disorder where the lower jaw outgrows the upper, resulting in an extended chin and a crossbite. In both humans and animals, it can be the result of inbreeding.[9]

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.[10]

In brachycephalic or flat-faced dogs, like shih tzus and boxers, it can lead to problems such as underbite.[11]

In humans, it results in a condition sometimes called lantern jaw, reportedly derived from the shape of early lanterns.[lower-alpha 1] Traits such as these were often exaggerated by inbreeding, and can be traced within specific families.[9][13]

Although the pathology is more common than appreciated, its best known historical example is Habsburg jaw, or Habsburg or Austrian lip, due to its prevalence in members of the House of Habsburg, which can be traced in their portraits.[14] The process of portrait-mapping has provided tools for geneticists and pedigree analysis; most instances are considered polygenic,[15] but a number of researchers believe that this trait is transmitted through an autosomal recessive type of inheritance.[16][14]

Allegedly introduced into the family by a member of the Piast dynasty, it is clearly visible on family tomb sculptures in St. 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,[17] due to the high number of consanguineous marriages in the dynasty preceding his birth.[16][14]

Charles II of Spain showing Habsburg jaw, a severe type of mandibular prognathism
File:Vlad Ţepeş, the Impaler, Prince of Wallachia (1456-1462) (died 1477).jpg
Vlad III of Wallachia
File:Arveprins Frederik (Juel).JPG
Frederick, regent of Denmark-Norway
File:Pedro II of Brazil 1851 edit.png
Pedro II of Brazil. His mother was Archduchess Maria Leopoldina of Austria, a member of the House of Habsburg-Lorraine by birth.

Treatment of mandibular prognathism

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 of orthodontics and orthognathic surgery. The orthodontics can involve braces, removal of teeth, or a mouthguard.[18]

In insects

In entomology, prognathous means that the mouthparts face forwards, being at the front of the head, rather than facing downwards as in some insects.[19]

See also

  • Dental pathology

Footnotes

  1. ↑ The OED uses a slightly different definition: "long thin jaws, giving a hollow appearance to the cheek". Earliest cited reference is from William Langland's 1362 Piers Plowman: "Hongur ...buffeted the Brutiner aboute bothe his chekes; he lokede lyk a lanterne al his lyf after."[12]

References

  1. ↑ 1.0 1.1 Peacock, Zachary S.; Klein, Katherine P.; Mulliken, John B.; Kaban, Leonard B. (September 2014). "The Habsburg Jaw-re-examined". American Journal of Medical Genetics. Part A 164A (9): 2263–2269. doi:10.1002/ajmg.a.36639. PMID 24942320. 
  2. ↑ Zamudio Martínez, Gabriela; Zamudio Martínez, Adriana (2020). "A Royal Family Heritage: The Habsburg Jaw". Facial Plastic Surgery & Aesthetic Medicine 22 (2): 120–121. doi:10.1089/fpsam.2019.29017.mar. PMID 32083497. 
  3. ↑ MedlinePlus Encyclopedia Prognathism
  4. ↑ Vioarsdóttir, O'Higgins & Stringer 2002, pp. 211–229.
  5. ↑ 5.0 5.1 Singh, Tenali Sushmitha; Sridevi, Enuganti; Sankar, Avula Jogendra Sai; Kakarla, Pranitha; Vallabaneni, Siva Sai Krishna; Sridhar, Mukthineni (2020). "Cephalometric Assessment of Dentoskeletal Characteristics in Children with Digit-sucking Habit". International Journal of Clinical Pediatric Dentistry 13 (3): 221–224. doi:10.5005/jp-journals-10005-1761. ISSN 0974-7052. PMID 32904107. 
  6. ↑ Sahil, Sahil; Soni, Sanjeev; Kaur, Gurpreet (2021-12-31). "Challenging Malocclusion in Orthodontics: the Open Bite" (in en). International Journal of Health Sciences: 125–134. doi:10.53730/ijhs.v5nS2.5581. ISSN 2550-6978. https://www.neliti.com/publications/426601/challenging-malocclusion-in-orthodontics-the-open-bite. 
  7. ↑ "Medical Definition of de Lange syndrome". https://www.medicinenet.com/de_lange_syndrome/definition.htm. 
  8. ↑ Rae, Todd C.; Koppe, Thomas; Stringer, Chris B. (27 October 2010). "The Neanderthal face is not cold adapted". https://edisciplinas.usp.br/pluginfile.php/6200375/mod_resource/content/1/The%20neanderthal%20face%20is%20not%20cold%20adapted%20%28Rae%20et%20al%202011%29.pdf. 
  9. ↑ 9.0 9.1 Vilas et al. 2019, pp. 563–571.
  10. ↑ Kulkarni, Shilpa Devdatt; Bhad, Wasundhara A.; Doshi, Umal H. (2020). "Association Between Mandibular Prognathism and MATRILIN-1 Gene in Central India Population: A Cross-sectional Study". Journal of Indian Orthodontic Society 55 (1): 28–32. doi:10.1177/0301574220956421. 
  11. ↑ Beuchat 2015.
  12. ↑ lantern jaw (3rd ed.), Oxford University Press, September 2005, http://www.oed.com/view/Entry/105665  (Subscription or UK public library membership required.)
  13. ↑ Online Mendelian Inheritance in Man (OMIM) PROGNATHISM, MANDIBULAR -176700
  14. ↑ 14.0 14.1 14.2 Vilas et al. 2019.
  15. ↑ Wolff, Wienker & Sander 1993, pp. 112–116.
  16. ↑ 16.0 16.1 Безуглый, Т. А. (2020). "Влияние На Человека Признаков, Передаваемых По Аутосомно-Рецессивному Типу (на Примере Династии Габсбургов)" (in ru). https://www.elibrary.ru/item.asp?id=44270977. 
  17. ↑ Mitchell 2013, pp. 303–308.
  18. ↑ "Treating Prognathism: Ways to Correct Abnormal Jaw Alignment". https://www.colgate.com/en-us/oral-health/developmental-disabilities/treating-prognathism-ways-to-correct-abnormal-jaw-alignment. 
  19. ↑ "Prognathous". https://www.earthlife.net/insects/glossary.html#16. 

General and cited sources

Classification
External resources

Template:Dentofacial anomalies and jaw disease



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