Corrective Jaw Orthognathic Surgery Animation
Corrective jaw surgery, or orthognathic surgery, is a group of procedures performed to correct dentofacial irregularities, most commonly manifested as misalignments of the jaws. These deformities not only cause malocclusion or bad bite, but also create problems in the temporomandibular joint the TMJ and the airway, resulting in difficulties chewing, swallowing, speaking and breathing. While the surgery is performed to correct functional problems, patient’s appearance may be dramatically improved as a result. Open bite is a condition where the upper and lower front teeth do not touch when the mouth is closed or at rest. An open bite can lead to a number of oral health conditions including.
Tooth wear, tooth breakage and TMJ disorders. It may also cause speech problems known as â€˜lisping’ in some individuals. Open bite surgery involves removing some of the bone of the upper jaw to move it to a new position. Once the jaws are aligned, plates and screws are used to secure the bones in place. Protruding lower jaw is corrected in a procedure called mandibular setback surgery. The toothbearing portion of the lower jaw is separated from its base and moved backward for proper alignment. In a similar way, receding lower jaw, or â€œweak chinâ€�, is corrected with mandibular advancement surgery. In this case, the toothbearing portion of the lower jaw is repositioned forward. Orthognathic surgeries are commonly performed.
In combination with orthodontic treatments and may take several years to complete.
The word mandible comes from the Latin word mandibula, which means jaw or jawbone. The mandible is the lower jawbone and it is the largest and strongest bone of the face. Everyday actions such as talking and chewing are some of the most important tasks that utilize the mandible. When performing these tasks, the temporomandibular joint allows the mandible to easily move up and down with the assistance of attached ligaments and muscles. The temporomandibular joint is composed of the condylar process of the mandible and the mandibular fossa of the temporal bone. Inferior to the condylar process is the ramus of the mandible and connecting the ramus to the body of the mandible is the mandibular angle. One of the most important muscles for chewing, the masseter, originates on the zygomatic bone and inserts at the mandibular angle and ramus. The masseter allows for the up and down motion that is necessary when chewing.
Superior to the mandibular angle is the coronoid process. The temporalis muscle inserts on the coronoid process and ensures that the mandible is able to move up and down. The alveolar processes form the superior border of the body of the mandible. The alveolar processes contain the alveoli, or tooth sockets. Just below the alveolar processes of the mandible is the alveolar margin. The alveolar margin can be felt with the tongue, just below the teeth on the mandible. The mandibular foramen contains the alveolar nerve, which supplies sensation to the teeth on the lower jawbone. When administering anesthetic, a dentist would feel for the mandibular foramen in order to inject the anesthetic into the alveolar nerve and temporarily eliminate tooth sensation. Located in the body of the mandible is the mental foramen. This foramen contains several nerves and blood vessels that lead to and from the lower lip and chin. Commonly referred to as the chin, is the mental protuberance this is where the mandible is fused together at the mandibular symphysis. The mandibular symphysis is formed when the two halves of the mandible are joined. The fusion usually occurs during the first 6 to 9 months after birth.
Fractures of the mandible are most easily classified by the location of the fracture such as condylar, alveolar, or ramus, but can also be classified as the type of fracture such as simple or compound. One of the most common locations for a mandibular fracture is of the condylar process. A condylar fracture could refer to the fracture of one or both condylar processes. This type of fracture can be dangerous because there is a potential for the fracture to cause the tongue to interfere with the airway. Most fractures generally require a cast to immobilize the bone, but since the mandible cannot be put into a cast, the mandible is often wired shut after the bone has been set in order to allow for proper healing without movement. Over time, some patients may develop a temporomandibular joint disorder, also known as a TMJ disorder, which can be caused by grinding teeth, stress, trauma, or simply just wear and tear on the temporomandibular joint. Symptoms of a TMJ disorder usually include pain andor swelling near the temporomandibular joint, but vary depending on the disorder. Since there are a large number of issues that can occur on or near the temporomandibular joint, pain around the temporomandibular joint is generally classified as a TMJ disorder. Included under the classification of TMJ disorders are dislocations, arthritis, inflammation, or infection on or near the temporomandibular joint.
Fortunately, most TMJ disorders are resolved without any specific treatment, but individuals that frequently experience TMJ disorders are often encouraged to take precautions such as wearing a mouth guard, cutting food into small pieces, and avoid chewing gum. These precautions can help to eliminate or minimize the stress on the temporomandibular joint. This tutorial was prepared as part of the course requirements of Human Anatomy at Saddleback College.