Condylar hyperplasia | |
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Other names | Mandibular hyperplasia |
Condylar hyperplasia (mandibular hyperplasia) is over-enlargement of the mandible bone in the skull. [1] It was first described by Robert Adams in 1836 who related it to the overdevelopment of mandible. In humans, the mandibular bone has two condyles which are known as growth centers of the mandible. [2] When growth at the condyle exceeds its normal time span, it is referred to as condylar hyperplasia. The most common form of condylar hyperplasia is unilateral condylar hyperplasia where one condyle overgrows the other condyle leading to facial asymmetry. Hugo Obwegeser et al. [3] classified condylar hyperplasia into two categories: hemimandibular hyperplasia and hemimandibular elongation. It is estimated that about 30% of people with facial asymmetry express condylar hyperplasia. [4]
In 1986, Obwegeser and Makek [3] specifically detailed two hemimandibular anomalies, hemimandibular hyperplasia and hemimandibular elongation. These anomalies can be clinically present in a pure form or in combination.
Condylar hyperplasia has an unknown cause. Several theories exist in literature which related to the cause of condylar hyperplasia. One theory states that an event of a trauma leading to increase in number of repair mechanism and hormones in that area may lead to increase in growth of mandible on that side. [5] Another theory states that an increase in loading of the temporomandibular joint can lead to increase in expression of bone forming molecules. [6] Condylar hyperplasia predominantly affects women with 64% of patients being women. [7]
Diagnosis of asymmetry can be done through many different methods. PA cephalometry, panoramic radiograph, and nuclear imaging are some of the techniques that can be used for diagnosis. [8] Primarily nuclear imaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), and bone scintigraphy are taken along with other data before a patient is diagnosed for Condylar Hyperplasia. [8] In SPECT imaging, an increase uptake of the isotope is seen on the affected in comparison to the non-affected side. A difference of at least 10% or a minimum ratio of 55% to 45% uptake of technetium-99m is seen when comparing affected vs non-affected side respectively. An uptake of more than 55% and difference of at least 10% indicates an active condylar growth. [9]
Hugo Obwegesr and Makek classified condylar hyperplasia into three categories, listed in the table below. [3] Type 1 develops its characteristics from the horizontal vector, and Type 2 develops its characteristics from the vertical vector. Type 1 CH occurs much more common (15x) than Type 2 CH. Wolford et al. [10] in 2014, developed an updated classification of condylar hyperplasia. In 1986, Slootweg & Muller devised a histopathological classification which allows the condylar tissues to be classified into specific categories. [11]
Type | Name | Clinical findings | Histological findings |
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Type 1 | Hemimandibular elongation | - Chin deviation towards contralateral side - Midline shift towards contralateral side - Posterior crossbite on contralateral side | - Excessive growth in the horizontal vector - Enlarged ramus, normal condyle |
Type 2 | Hemimandibular hyperplasia | - Sloping rima oris with minimal chin deviation - Supra-eruption of maxillary molars on affected side - Open bite - Midline shift (minimal to none) | - Excessive growth in the vertical vector - Excessive growth in the condylar head |
Type 3 | Combination of both | - Chin deviation towards contralateral side - Possible open bite - Sloping rima oris with possible chin deviation | - Combination of excessive growth in both vectors |
Many treatment options exist for this type of condition. Orthognathic surgery can be performed once the active condylar growth has finished in some cases. The point of this surgery to wait as long as the condyle is growing and only do surgery when the condyle stops growing, so the chances of any worsening of facial asymmetry lessens. This option, however, does include a person living with the facial asymmetry features all the way up until 18 to 19 years of age. A procedure called condylectomy can also be done which involves removing part of the growing condyle to arrest any active growth. [12] Sometimes condylectomy can be done in conjunction with articular disk repositioning and orthognathic surgery to treat patients with mandibular hyperplasia, such as shown by Wolford et al. [13]
In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the condylar process of mandible below; it is from these bones that its name is derived. The joints are unique in their bilateral function, being connected via the mandible.
Orthognathic surgery, also known as corrective jaw surgery or simply jaw surgery, is surgery designed to correct conditions of the jaw and lower face related to structure, growth, airway issues including sleep apnea, TMJ disorders, malocclusion problems primarily arising from skeletal disharmonies, and other orthodontic dental bite problems that cannot be treated easily with braces, as well as the broad range of facial imbalances, disharmonies, asymmetries, and malproportions where correction may be considered to improve facial aesthetics and self-esteem.
The depressor labii inferioris is a facial muscle. It helps to lower the bottom lip.
Hemifacial microsomia (HFM) is a congenital disorder that affects the development of the lower half of the face, most commonly the ears, the mouth and the mandible. It usually occurs on one side of the face, but both sides are sometimes affected. If severe, it may result in difficulties in breathing due to obstruction of the trachea—sometimes even requiring a tracheotomy. With an incidence in the range of 1:3500 to 1:4500, it is the second most common birth defect of the face, after cleft lip and cleft palate. HFM shares many similarities with Treacher Collins syndrome.
Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, the chubby-faced infants featured in Renaissance paintings, which were often mistakenly described as cherubs.
The mandibular fossa, also known as the glenoid fossa in some dental literature, is the depression in the temporal bone that articulates with the mandible.
Jaw reduction or mandible angle reduction is a type of surgery to narrow the lower one-third of the face—particularly the contribution from the mandible and its muscular attachments. There are several techniques for treatment—including surgical and non-surgical methods. A square lower jaw can be considered a masculine trait, especially in Asian countries. As a result, whereas square lower jaws are often considered a positive trait in men, a wide mandible can be perceived as discordant or masculine on women, or sometimes in certain men, particularly when there is asymmetry.
Facial trauma, also called maxillofacial trauma, is any physical trauma to the face. Facial trauma can involve soft tissue injuries such as burns, lacerations and bruises, or fractures of the facial bones such as nasal fractures and fractures of the jaw, as well as trauma such as eye injuries. Symptoms are specific to the type of injury; for example, fractures may involve pain, swelling, loss of function, or changes in the shape of facial structures.
Cephalometric analysis is the clinical application of cephalometry. It is analysis of the dental and skeletal relationships of a human skull. It is frequently used by dentists, orthodontists, and oral and maxillofacial surgeons as a treatment planning tool. Two of the more popular methods of analysis used in orthodontology are the Steiner analysis and the Downs analysis. There are other methods as well which are listed below.
Mandibular fracture, also known as fracture of the jaw, is a break through the mandibular bone. In about 60% of cases the break occurs in two places. It may result in a decreased ability to fully open the mouth. Often the teeth will not feel properly aligned or there may be bleeding of the gums. Mandibular fractures occur most commonly among males in their 30s.
A jaw abnormality is a disorder in the formation, shape and/or size of the jaw. In general abnormalities arise within the jaw when there is a disturbance or fault in the fusion of the mandibular processes. The mandible in particular has the most differential typical growth anomalies than any other bone in the human skeleton. This is due to variants in the complex symmetrical growth pattern which formulates the mandible.
Dislocations occur when two bones that originally met at the joint detach. Dislocations should not be confused with subluxation. Subluxation is when the joint is still partially attached to the bone.
In jawed vertebrates, the mandible, lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth.
Condylar resorption, also called idiopathic condylar resorption, ICR, and condylysis, is a temporomandibular joint disorder in which one or both of the mandibular condyles are broken down in a bone resorption process. This disorder is nine times more likely to be present in females than males, and is more common among teenagers.
The development of craniofacial growth is a complicated phenomenon that has been the subject of much research for past 70 years. From the first theory in 1940s, many different ideas pertaining to how a face develops has intrigued the minds of researchers and clinicians alike.
Richard Trauner was an Austrian oral surgeon. Trauner is known for introducing the procedure of Sagittal Split Osteotomy to the United States in the 1960s with Hugo Obwegeser.
Hugo Obwegeser was an Austrian Oral and Maxillo-Facial Surgeon and Plastic Surgeon who is known as the father of the modern orthognathic surgery. In his publication of 1970, he was the first surgeon to describe the simultaneous procedure which involved surgeries of both Maxilla and Mandible involving Le Fort I and Bilateral Sagittal Split Osteotomy technique.
Condylar hypoplasia is known as underdevelopment of the mandibular condyle. Congenitally (primary) caused condylar hypoplasia leads to underdeveloped condyle at birth. Hypoplasia of mandible can be diagnosed during birth, in comparison to the hyperplasia which is only diagnosed later in growth of an individual.
Mandibular setback surgery is a surgical procedure performed along the occlusal plane to prevent bite opening on the anterior or posterior teeth and retract the lower jaw for both functional and aesthetic effects in patients with mandibular prognathism. It is an orthodontic surgery that is a form of reconstructive plastic surgery. There are three main types of procedures for mandibular setback surgery: Bilateral Sagittal Split Osteotomy (BSSO), Intraoral Vertical Ramus Osteotomy (IVRO) and Extraoral Ramus Osteotomy (EVRO), depending on the magnitude of mandibular setback for each patient. Postoperative care aims to minimise postoperative complications, complications includes bite changes, relapse and nerve injury.
Joel Ferri is a French Stomatologist, Oral and Maxillofacial Surgeon, academic and author. He is the chairman and head of the Department of Oral and Maxillofacial Surgery at the Lille Medical School.