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Upper jaw underdevelopment (upper micrognathia, opistognathia): causes, symptoms, diagnosis, treatment
Medical expert of the article
Last reviewed: 05.07.2025
Underdevelopment of the upper jaw (upper micrognathia, opisthognathia) is a type of deformation that is relatively rare and very difficult to treat surgically.
What causes underdevelopment of the upper jaw (upper micrognathia, opisthognathia)?
Underdevelopment of the upper jaw can be caused by endo- and exogenous factors: dysfunction of the endocrine system, congenital non-fusion of the upper lip, alveolar process and palate, nasal breathing disorders, bad habits, previous inflammatory processes of the maxillary bone (osteomyelitis, sinusitis, noma, syphilis, etc.).
Micrognathia often develops as a result of early uranoplasty for congenital non-fusion of the palate.
Symptoms of underdevelopment of the upper jaw (upper micrognathia, opisthognathia)
Micrognathia is a type of so-called "mesial" bite, which occurs in three forms:
- I - underdevelopment of the upper jaw against the background of a normally developed lower jaw;
- II - normally developed upper jaw against the background of excessive development of the lower jaw;
- III - underdevelopment of the upper jaw, combined with excessive development of the lower jaw.
The surgeon has to differentiate true micrognathia (forms I and III) from false micrognathia (form II), in which the upper jaw only appears underdeveloped due to the excessive development of the lower jaw.
Externally, true underdevelopment of the upper jaw is manifested by the sinking of the upper lip and a sharp protrusion of the nose forward. The impression of hypertrophy of the lower lip and chin ("offended profile") is created.
It is impossible to bite off food, since the lower teeth, not finding antagonists, shift forward and upward along with the alveolar process, sometimes causing a picture of a deep reverse bite.
The nasolabial folds are clearly expressed.
The patients' speech is somewhat impaired, and the pronunciation of dental sounds is unclear.
Where does it hurt?
Treatment of underdevelopment of the upper jaw (upper micrognathia, opisthognathia)
Previously, such deformation of the upper jaw was practically not treated surgically, but was limited to deepening the vestibule of the mouth and making a maxillary prosthesis with a protruding frontal section.
Such caution and “passivity” of surgeons is explained by the fact that from time to time in the literature there appear reports of complications of various natures both during and after surgery: significant profuse bleeding, sometimes ending in the death of the patient; partial necrosis of osteotomized fragments; development of subcutaneous emphysema of the face, neck, mediastinum; occlusion of the internal carotid artery; thrombosis of the carotid artery and cavernous sinus.
Frequent relapses of the disease were alarming, reaching 100% according to various authors. Whitaker et al., summarizing the experience of four centers for the treatment of craniofacial deformities, came to the conclusion that in reconstructive surgeries, more than 40% of cases, complications of one kind or another are observed.
However, persistent demands from patients with midface deformities encourage surgeons to resort to radical correction of cosmetic and functional facial deformities (especially in young and middle-aged patients).
Patients motivate surgeons to work on such complex problems as determining the optimal time for surgery, the method and degree of forward mobilization of the upper jaw; the method of fixing the displaced jaw or part of it; the choice of transplants for their placement in the gaps formed after osteotomy of fragments or the entire jaw; eliminating the discrepancy between the new function of the displaced upper jaw and the anatomical shape of the lower jaw; ensuring the growth of the displaced jaw in a patient with incomplete development of the entire facial skeleton; determining the optimal design of the orthodontic device for use after surgery, etc., etc. These problems are gradually being solved by both domestic and foreign surgeons.
Hyperbaric oxygenation, which increases the patient's resistance, contributes to a significant reduction in the risk of complications after surgical reconstructive operations.
Currently, sometimes operations are used in the form of moving forward the entire alveolar process and teeth of the upper jaw or partially moving forward only the frontal part of the jaw together with the teeth.