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In disease states, maxillary prognathism is associated with Cornelia de Lange syndrome; 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.
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.
Not all alveolar prognathism is anomalous, and significant differences can be observed among different ethnic groups.
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 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.
Stafne defect is uncommon, and has been reported to develop anywhere between the ages of 11 and 30 years old, (although the defect is developmental, it does not seem to be present form birth, implying that the lesion develops at a later age). Usually the defect is unilateral (on one side only) and most commonly occurs in men.
Behavior therapy is important especially when the kids are in their primary dentition in the pre-adolescent age. Improving habits at this time may lead to self-correction of open bite in many cases. Sometimes presence of infantile swallowing into early childhood may lead to an anterior open bite in patients. Habit control through appliances such as Tongue crib or Tongue spurs may be used in adolescent ages if the behavior modification fails to stop the habit.
Retrognathia (or retrognathism) is a type of malocclusion which refers to an abnormal posterior positioning of the maxilla or mandible, particularly the mandible, relative to the facial skeleton and soft tissues.
A retrognathic mandible is commonly referred to as an overbite, though this terminology is not used medically.
A jaw abnormality is disorder in the formation or shape of the jaw. It can involve malocclusion.
Types include:
- Micrognathism
- Prognathism
- Retrognathism
- Pierre Robin syndrome
Treatment is surgical. Osteotomies may be done in case of maxillary macrognathia. Mandibular macrognathia is generally managed by resection of a portion of the mandible followed by orthodontic treatment.
Extra teeth, lost teeth, impacted teeth, or abnormally shaped teeth have been cited as causes of malocclusion. A small underdeveloped jaw, caused by lack of masticatory stress during childhood, can cause tooth overcrowding. Ill-fitting dental fillings, crowns, appliances, retainers, or braces as well as misalignment of jaw fractures after a severe injury are other causes. Tumors of the mouth and jaw, thumb sucking, tongue thrusting, pacifier use beyond age 3, and prolonged use of a bottle have also been identified as causes.
In an experiment on two groups of rock hyraxes fed hardened or softened versions of the same foods, the animals fed softer food had significantly narrower and shorter faces and thinner and shorter mandibles than animals fed hard food. Experiments have shown similar results in other animals, including primates, supporting the theory that masticatory stress during childhood affects jaw development. Several studies have shown this effect in humans. Children chewed a hard resinous gum for two hours a day and showed increased facial growth.
During the transition to agriculture, the shape of the human mandible went through a series of changes. The mandible underwent a complex series of shape changes not matched by the teeth, leading to incongruity between dental and mandibular form. These changes in human skulls may have been "driven by the decreasing bite forces required to chew the processed foods eaten once humans switched to growing different types of cereals, milking and herding animals about 10,000 years ago."
Crowding of the teeth is treated with orthodontics, often with tooth extraction, clear aligners, or dental braces, followed by growth modification in children or jaw surgery (orthognathic surgery) in adults. Surgery may be required on rare occasions. This may include surgical reshaping to lengthen or shorten the jaw (orthognathic surgery). Wires, plates, or screws may be used to secure the jaw bone, in a manner similar to the surgical stabilization of jaw fractures. Very few people have "perfect" alignment of their teeth. However, most problems are very minor and do not require treatment.
Mandible fracture causes vary by the time period and the region studied. In North America, blunt force trauma (a punch) is the leading cause of mandible fracture whereas in India, motor vehicle collisions are now a leading cause. On battle grounds, it is more likely to be high velocity injuries (bullets and shrapnel). Prior to the routine use of seat belts, airbags and modern safety measures, motor vehicle collisions were a leading cause of facial trauma. The relationship to blunt force trauma explains why 80% of all mandible fractures occur in males. Mandibular fracture is a rare complication of third molar removal, and may occur during the procedure or afterwards. With respect to trauma patients, roughly 10% have some sort of facial fracture, the majority of which come from motor vehicle collisions. When the person is unrestrained in a car, the risk of fracture rises 50% and when an unhelmeted motorcyclist the risk rises 4-fold.
Smoking and tobacco use of any kind are associated with increased risk of dry socket. This may be partially due to the vasoconstrictive action of nicotine on small blood vessels. Abstaining from smoking in the days immediately following a dental extraction reduces the risk of a dry socket occurring.
Literature states that very few crossbites tend to self-correct which often justify the treatment approach of correcting these bites as early as possible. Only 0–9% of crossbites self-correct. Lindner et al. reported that in a 50% of crossbites were corrected in 76 four year old children.
Man-Suk Baek and others evaluated long-term stability of anterior open bite by intrusion of maxillary posterior teeth. Their results showed that the molars were intruded by 2.39mm during treatment and relapsed back by 0.45mm or 22.8%. The incisal overbite increased by 5.56mm during treatment and relapsed back by 1.20mm or 17%. They concluded that majority of the relapse occurred during first year of treatment.
Vasoconstrictors are present in most local anesthetics, and are intended to increase the length of analgesia by reducing blood supply to the region which reduces the amount of local anesthetic solution that is absorbed into the circulation and carried from the local tissues. Hence, use of local anesthetics with vasoconstrictors is associated with an increased risk of dry socket occurring. However, frequently use of local anesthetic without vasoconstrictors would not provide sufficient analgesia, especially in the presence of acute pain and infection, meaning that the total dose of local anesthetic may need to be increased. Adequate pain control during the extraction is balanced against an increased risk of dry socket.
Torus mandibularis "(pl. tori mandibulares)" (or mandibular torus "(pl. mandibular tori)" in English) is a bony growth in the mandible along the surface nearest to the tongue. Mandibular tori are usually present near the premolars and above the location of the mylohyoid muscle's attachment to the mandible. In 90% of cases, there is a torus on both the left and right sides, making this finding a predominantly bilateral condition.
The prevalence of mandibular tori ranges from 5% - 40%. It is less common than bony growths occurring on the palate, known as torus palatinus. Mandibular tori are more common in Asian and Inuit populations, and slightly more common in males. In the United States, the prevalence is 7% - 10% of the population.
It is believed that mandibular tori are caused by several factors. They are more common in early adult life and are associated with bruxism. The size of the tori may fluctuate throughout life, and in some cases the tori can be large enough to touch each other in the midline of mouth. Consequently, it is believed that mandibular tori are the result of local stresses and not due solely to genetic influences.
Mandibular tori are usually a clinical finding with no treatment necessary. It is possible for ulcers to form in the area of the tori due to trauma. The tori may also complicate the fabrication of dentures. If removal of the tori is needed, surgery can be done to reduce the amount of bone, but the tori may reform in cases where nearby teeth still receive local stresses.
Unilateral crossbite involves one side of the arch. The most common cause of unilateral crossbite is a narrow maxillary dental arch. This can happen due to habits such as digit sucking, prolonged use of pacifier or upper airway obstruction. Due to the discrepancy between the maxillary and mandibular arch, neuromuscular guidance of the mandible causes mandible to shift towards the side of the crossbite. This is also known as Functional mandibular shift. This shift can become structural if left untreated for a long time during growth, leading to skeletal asymmetries. Unilateral crossbites can present with following features in a child
- Lower midline deviation to the crossbite side
- Class 2 Subdivision relationships
- Temporomandibular disorders
The healing time for a routine mandible fractures is 4–6 weeks whether MMF or rigid internal fixation (RIF) is used. For comparable fractures, patients who received MMF will lose more weight and take longer to regain mouth opening, whereas, those who receive RIF have higher infection rates.
The most common long-term complications are loss of sensation in the mandibular nerve, malocclusion and loss of teeth in the line of fracture. The more complicated the fracture (infection, comminution, displacement) the higher the risk of fracture.
Condylar fractures have higher rates of malocclusion which in turn are dependent on the degree of displacement and/or dislocation. When the fracture is intracapsular there is a higher rate of late-term osteoarthritis and the potential for ankylosis although the later is a rare complication as long as mobilization is early. Pediatric condylar fractures have higher rates of ankylosis and the potential for growth disturbance.
Rarely, mandibular fracture can lead to Frey's syndrome.
Macrognathism is the condition of abnormally large jaws. It is also called "megagnathia" (antonym: micrognathia).
Overbite medically refers to the extent of vertical (superior-inferior) overlap of the maxillary central incisors over the mandibular central incisors, measured relative to the incisal ridges.
The term overbite does not refer to a specific condition, nor is it a form of malocclusion. Rather an absent or excess overbite would be a malocclusion. Normal overbite is not measured in exact terms, but as a proportion (approximately 30–50% of the height of the mandibular incisors) and is commonly expressed as a percentage.
Macroglossia is uncommon, and usually occurs in children. Macroglossia has been reported to have a positive family history in 6% of cases. The National Organization of Rare Disorders lists macroglossia as a rare disease (less than 200 000 individuals in the US).
Condylar resorption is an idiopathic condition, though there are some theories relating to its possible cause. Because condylar resorption is more likely to be in young females, hormonal mediation may be involved. Strain on the temporomandibular joint from orthodontics or orthognathic surgery may be related to the condition. Reactive arthritis, rheumatoid arthritis, and psoriatic arthritis are other possible causes.
These lesions usually present in neonates, although they may not come to clinical attention until adulthood (for cosmetic reasons). There is no gender predilection. They are present in approximately 3-6 per 1000 live births.
Macrostomia, (from the Greek prefix "makro-" meaning "large" and from Greek , "mouth") refers to a mouth that is unusually wide.
Macrostomia is characterized as a physical abnormality that causes clefts to form on the face of affected individuals. These clefts can form on either or both sides of the face, but they are most commonly seen on the right cheek and have a higher rate of occurrence in males. Macrostomia is very irregular and on average occurs only once in every 150,000 to 300,000 live births. It's unusual for macrostomia to occur on its own and it is included as a symptom for many diseases including craniofacial microsomia. The clefts result from improper development and fusion of the mandibular and maxillary processes. The clefts cause problems with facial muscle development. The origin of macrostomia is not yet fully understood it could have multiple causes.
An oral torus is a lesion made of compact bone and occurs along the palate or the mandible inside the mouth. The palatal torus or "torus palatinus" occurs along the palate, close to the midline, whereas the mandibular torus or "torus mandibularis" occur along the lingual side of the mandible.
Occurrences of tori are more frequent in women than in men. Tori are associated with adulthood and rarely appear before the age of 15. The palatal version of tori have a higher occurrence in Native American and Inuit populations.
Treatment is not necessary unless they become an obstruction to chewing or prosthetic appliances.
It is a classed as a pseudocyst, since there is no epithelial lining or fluid content. This defect is usually considered with other cysts of the jaws, since it can be mistaken for such on a radiograph.