Correctıve Jaw Surgery – Orthognatic Surgery

4 January 2018
Çene cerrahisi - kemal uğurlu

The face is one of the most important parts of the body in every respect. In addition to its basic aesthetic appearance, it is the region where many vital functions such as eating, breathing, speaking, mimicry, taste, feeling, etc. are made. Anatomically; we see that the upper and lower jaws cover two thirds of the face when we distinguish between upper (forehead), middle (upper jaw-cheeks) and lower face (lower jaw). Jaw bones; unlike other bones, they have teeth on them and are in close co-operation with them. Corrective jaw surgery is the department of surgery that covers all diseases such as congenital-developmental diseases and trauma-tumors of this region.

Structural and Functional Properties of Jaw Bones

To better understand corrective jaw surgery, it is helpful to look at the anatomical features of the region. Jaw bones; are evaluated in two separate parts taking into consideration the structural features of the segments with teeth and those without teeth. Alveolar bone (toothed segment); A spongy structure in the teeth that is attached to the teeth by special bonds and is a soft-bone segment that allows minimal movement. This bone that surrounds the teeth can survive only with the teeth, when the teeth are pulled, it is pulled slowly and leaves a space of for a bone in place. Gingival weakness in this area may cause a reduction in soft tissue support, resulting in aesthetic problems, as well as the misalignment of other teeth into this region, which may result in a deterioration of the healing due to the change in the relationship between the two jaws. Orthodontic treatment can be carried out by correcting the misalignment of the teeth, bringing the teeth to the appropriate area, burying the teeth, stretching the teeth, etc., all due to the structural properties of the alveolar bone.

Bacillar (basic) bone;

It is the basic compact (hard) bone part of the upper and lower jaw. It carries the alveolar bone on top. It provides the sense that the alveolar bone and teeth are nourished by the veins and the nerves it contains. It is a hard and durable bone, but the alveolar gets weaker and starts to dissolve in parallel to the bone being pulled. The risk of fracture in this area increases. The upper jaw (maxilla) and the lower jaw (mandibular) bones provide support to soft tissues on a large scale, just like in other parts of the body, and allow them to function properly. Between themselves they form a biting plan through the jaw joint (temporo-mandibular joint). Normally, the upper jaw’s teeth overlap the lower jaw’s teeth and should be slightly forward. It ensures that all the teeth of the upper and lower jaws are in harmony with each other and that they are in contact with each other at the same time. Otherwise, even one tooth which is not in position can disrupt the whole bite plan between the two jaws. Biting disorders in the jaw can occur for various reasons. It is a frequent cause of developmental disorders, traumas, genetic or racial traits, inadequate habits (finger sucking, prolonged bottle use, etc.), premature tooth extraction, delayed treatment of unequal teeth, and an extra large tongue. Some bone diseases, benign tumors, vascular diseases (hemangiomas) are less common causes.

Orthodontic treatment of the teeth in the alveolar bone segment and the alignment of teeth and a good bite (occlusion) can be provided. However, if the problem is in the bacillary bone, the alignment of the teeth is not enough to correct the bite, and the skeletal structure, that is, at the baciallar level the upper and lower jaws should be brought to the appropriate places corrective by jaw surgery. Patients whose bite is not good may have many medical problems. Food can not be well-grounded, speech disorders, respiratory disorders, premature tooth decay, gingival crevices, bad breath, dysfunctions and pain in the jaw joint can be seen. For example, a person with a very small lower jaw; may experience significant respiratory and sleep problems which can be associated with heart diseases. Those whose mouths are always open because their teeth do not close wellwill have deteriorated oral hygiene since they have problems with chewing their food.

Examination

Patients who come for corrective surgery due to biting disorders are first subjected to detailed face and mouth examinations, and dynamic problems are examined during the movement of the jaw joint. The asymmetry (equality of one side of the face to the other) is determined by the proportional evaluation of the volumes and dimensions of the different regions of the face (forehead, eyes, cheeks, nose, etc.) between the right and left sides. Differences in soft tissue lay-outs are investigated. Especially size of the lips and its dynamic positions when laughing are very important.

In corrective jaw surgery;

When we divide the face into three parts, each part must be equal, the base of the head (upper face), middle of the face (upper jaw-maxilla) and lower part of the face (lower jaw) are equal parts. This is called the golden ratios of Lenardo Vinci. This gives us an idea clinically about the proportions and balance of the face within itself. The head; in healthy people neck is balanced on top of the spinal bones just like scales. If we consider the neck bones as the center of a balance, the weight of the structures in the front part of the face should be approximately equal to the weight of the back part of the head. A smaller jaw than the nose, a more forward lower jaw compared to the upper jaw, a head with a larger back than the front of the face is to protect the macro static balances of the head.

After the number of teeth, their individual positions, cavities, past treatments, dimensions of the tounge and volume are assessed, the dental relationship-biting (occlusion) of the lower and upper jaws is evaluated. In corrective jaw surgery, the upper anterior teeth (located at about 110 degrees to the upper jawbone) are in front of the lower anterior teeth (located at about 90 degrees on the lower jawbone) and overlap it slightly. This is how a natural bite is. This bite is medically called class I (class I) bite. Sometimes we can evaluate this bite according to canine (dog) teeth. If the upper teeth are in front of the lower teeth when the bite is examined, this bite is classified as class II (malocclusion) and if the lower teeth are higher than the upper teeth, it is called class III (class III) malocclusion (malocclusion). Apart from this, the teeth have the same bite connections on the sides. The narrowness of a jaw can create the same problem by disrupting its relationship with the other. While minimal biting and tooth alignment problems can be solved only orthodontically, biting disorders related to upper and lower jaw skeletons (facial bone), facial and jaw asymmetries should be corrected with corrective jaw surgery.

Radiology

Special x-rays (cephalometry graphs) are taken so that a more detailed examination can be done in patients who may need corrective jaw surgery. All skeletal structure of the head and face and positions of the teeth are evaluated with these graphs and it is investigated whether the problem is with the skeletal structure (ie ossicular bone) or with the dental structucture (dental-alveolar) complex. In patients with biting disorders, the problem is both skeletal and dental. Cephalometric measurements are made by taking into consideration the ratio of the sizes of the upper, middle and lower face to the base of the head and the soft tissue (especially the cheeks and lips).

Pre-surgery

After radiology, dental plaster molds of upper and lower jaws are taken as preparation for jaw surgeon and pre-treatment situations of dental relations are determined. According to skeletal and dental problems, orthodontic treatment is started after a suitable surgical foresight.
Orthodontic treatment takes between 6 months and 24 months. Orthodontics should start after the age of 12 years old in the last permanent teeth. Ideal timing can be done from 12 to 18 years of age until the age of jaw surgery. Because orthodontic treatment planning is very featured, planning; It is very important that the surgeon knows the preparations and that this is done by the experienced orthodontists and that the treatment is followed with intervals. Unplanned planning and poor orthodontic treatment can lead to major problems.
Sometimes patients are not informed adequately, because of the orthodontists who do not have enough surgical experience, the teeth of patients with skeletal insufficiency at the bone level are tried to be corrected only by orthodontic treatment, which causes insufficient and bad results. Most of the teeth are turning back to their old positions. As tooth roots are excessively challenged, teeth are shaking, gums are pulling, aesthetic result is inadequate and similar problems are experienced. In order to survive these problems, it is necessary to plan the treatment with an experienced orthodontist and to get advice from an experienced plastic surgeon. Orthodontic treatment that has been initiated improperly is often not possible.

Corrective Jaw surgery (Orthognathic surgery)

Orthognatic surgery is usually performed after 17-18 years of age. It can be performed on anyone with a suitable jaw bone until advanced ages. For example, it can be performed on patients who are suffering from sleep apnea. For patients treated according to surgical planning and have completed orthodontic treatment, an acrylic plate called a bite plate is made before the jaw surgery. If surgery is to be performed in one jaw, 1, if two jaws are to be operated, 2 bite plates are prepared. These are intended to provide the ideal position of the jaws during surgery relative to the base of the skull, and the ideal tooth correlation between each other (occlusion).

Corrective Jaw Surgery Techniques

There are three commonly used operations in orthognathic surgery.
Lefort I surgery applied in upper jaw disorders, sagittal split surgery applied in lower jaw disorders and genioplasty surgery applied in jaw disorders. All of these operations are performed under general anesthesia, each taking 1-2 hours on average. 1-2 day hospital stay is enough. Recovery is usually between 1 and 3 weeks.

Lefort I Surgery;

Corrective jaw surgery is performed by making an incision between the upper lip and the upper jawbone inside the mouth. (Osteotomized) in the upper jaw skeletal disorders (deformities), from the upper jawbone nose floor, through the root of the teeth. At this time, the upper jaw is only caught by the soft palate and is nourished by the vessels from it. The upper jaw-toothed bone segment, which moves in three dimensions; The ideal is achieved by placing a previously prepared intermediate bite plate. The remaining part of the upper jaw is secured in the new position by means of mini-plates (small, stainless alloy-punched metal) and screws. According to the needs of the upper jaw, all procedures such as embedding, sagging and rotation can be moved forward. The incision in the mouth is stitched with a self-dissolving thread and heals without any scarring. If there is a significant septum (nose) deviation during the operation, it can be corrected and the nasal tip can be somewhat reduced. Likewise, soft tissues can also be fixated on to the bone.

Mandibular Sagittal split (longitudinal dissection of the lower jaw) surgery;

According to what’s required, it is performed to bring the lower jaw back in skeletal disorders (deformities) of the lower jaw. Corrective jaw surgery is performed inside the mouth with a 3-4 cm incision made on the lower jaw bone behind the teeth on both sides without leaving a scar. There’s a nerve which passes through the lower jawbone (mandible), giving the lower lip a sense of lower teeth. This nerve is carefully preserved during the operation; the bone is horizontally separated into two as inner and outer folium. The nerve stays inside the inner foliums and is checked whether it has been damaged or not. Very rarely, if the nerve is damaged, it will be repaired with a microsurgical technique (under the microscope). The bite plate prepared for the lower jaw is placed between the teeth and when the ideal location of the lower jaw and the bite is determined, the two bone foliums separated from each other are fixated tgether with a screw into their new position. The screws are placed in very small holes of 3-4 mm which open on both sides. The scars disappear after a while and will not become visible.

Chin surgery (mentoplasty); the surgery is performed with a 3-4 cm incision made between the bones and the lips. The lower jaw bone is cut (osteotomized) so that the roots of the teeth are protected according to the structure of the defect. Meanwhile, the jaw bone segment, which feeds on the vessels from the muscles and becomes mobile, can be moved back and forward if there’s need, keeping it hidden-exposed or rotation can be done and the bone is fixated with mini plaques and screws. The incisions inside the mouth are not visible and are stitched with self-dissolving threads.

Care after Corrective Jaw Surgery

In patients who undergo corrective jaw surgery, pain relievers, antibiotics and treatments are used to reduce swelling in the face, as well as IV injections. It is very uncommon for the patient to be in intensive care. Food intake starts the next day with liquid foods. After the general condition of the patient is established, usually the lower and upper jaws are fixed to each other with elastic bands 2-4 days after the operation and the mouth is closed for 1-3 weeks. This makes healing of the bone safer.

Posted in Blog, Lower Jaw Surgery, Orthognathic Surgery, Surgery Practicies by Prof. Dr. Kemal UĞURLU

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