Orthognathic Surgery

Orthognathic Surgery
There is a direct relationship between facial skeletal abnormalities and malocclusions, jaw asymmetry and open bite deformities. A strong correlation has been demonstrated between the state of a patient’s occlusion and his or her chewing efficiency. Scientific studies have shown that many patients with skeletal malocclusions suffer from a variety of functional impairments, including diminished bite forces, restricted lower jaw excursions and abnormal chewing patterns, and temporomandibular disorders. While the etiology of facial skeletal deficiencies is not fully understood, it is known that patients with these deformities have pathologic alteration in their muscle fibers when compared to those with normal facial skeletons.

What is Orthognathic surgery?

Orthognathic surgery is the surgical correction of abnormalities of the mandible, maxilla, or both. The underlying abnormality may be present at birth or may become evident as the patient grows and develops or may be the result of traumatic injuries. The severity of these deformities precludes adequate treatment through dental treatment alone.

The definition of Orthognathic means “straight jaw”. Often a patient may visit the orthodontist to have their teeth straightened and obtain a better and healthier bite. However there is a small group of patients that will require the expertise of the oral surgeon to help the orthodontist get the bite correct. This is because not only are the teeth crooked but also the jaw itself is not in correct alignment. A growth problem, traumatic injury, or pathologic process of the upper, lower or both jaws are common causes of this problem.

When should you go for it?

  • Lower jaw too big – “Prognathism”
  • Lower jaw too small – “Micrognathia”
  • Lower jaw crooked – “Asymmetry
  • Upper jaw too big – “Maxillary procumbency”
  • Upper jaw too small“Maxillary/midface deficiency”
  • Cannot close teeth together – “Apertognathia/open bite

Do you fit into one of these categories?

To find out if the skeleton is not in proper position the Oral and Maxillofacial surgeon will examine several areas of data to develop a plan to analyze the problem at hand. This exam includes special radiographs that allow us to measure the sizes of the bones, clinical photographs use to overlay on the x-rays, models of the teeth, and actual measurements of the face and teeth. This data will allow us to make an “architectural” analysis of the skeletal discrepancies. Then a surgical plan is created to determine which jaw will need to be repositioned to correct the problem.
Several surgical techniques have been developed to allow the surgeon to repositioning the upper or lower jaw or sometimes both. The goals of the surgery are to balance the skeleton and the bite thereby improving function, speech, breathing, chewing and esthetics. Once the bone is in the correct position then the orthodontist can properly finish aligning the teeth. This type of surgery is typically done once skeletal growth is complete.

  • LeFort I Maxillary osteotomy: Moving the upper jaw in any position.
  • Sagittal Split Mandibular osteotomy : Used to move the lower jaw forward or backward
  • Vertical Ramus Mandibular osteotomy: Used to move the lower jaw backward.
  • Anterior Mandibular horizontal osteotomy: used to adjust the chin to stay in alignment with the profile.

Other members of the Dental team are necessary to make it all fall into place. Thus the patient that requires corrective jaw surgery to align the bite will require:

  • DENTIST: To make sure that the teeth and supporting structures are in excellent health.
  • ORTHODONTIST: To straighten the teeth prior to moving the bones with surgery and then refine the bite once the bones are healed.
  • ORAL AND MAXILLOFACIAL SURGEON: To reposition the jaws.

From a timeline perspective:

First an evaluation by the maxillofacial team is done. This typically takes about an hour at your initial visit. This is the time when all of the data is collected such as radiographs, photography, models, facial measurements and a health history. It is important to discuss with the surgeon previous surgery, hospitalizations and medications as this may impact on your surgical care and planning for a safe anesthetic.

A second follow up visit to the office will allow us the necessary time to compile the data and create the analyses necessary to determine if corrective jaw surgery is appropriate for you. This will be discussed at length with you and any family members that may come. A demonstration of computer generated surgery on you at that time may be available. This also takes about an hour.
To move forward with the surgery then a visit to the orthodontist is next. The doctor will place appliances (braces) on your upper and lower teeth to align and level them into the correct position within the bone. Typically it takes anywhere from 6 to 12 months of preparation. During that time we will be checking on you periodically to see the progress of tooth alignment so that we may plan ahead for your surgical date.

Once the alignment of the teeth is accomplished you will come back to us for a final surgical work up. At this time we will be taking new records. We will create a scale model of your jaws and perform the surgery to create guides to use in the operating room. This allows us to navigate through your surgery smoothly and precisely position the bones into the correct position.
The operation takes place in one of the many hospitals we are affiliated with. The average length of stay for two jaw surgery is two nights.

Once the surgery is completed the bones that have been repositioned at this point are healing into their new location. It takes 8 weeks for the bone to be hard enough to return to full function. Thus a diet of liquid to soft consistency is necessary so as not to traumatize the delicately healing bone. Along the same lines your activity will be limited to no strenuous activity for at least 4 months. These are things like contact sports, heavy weight lifting, and any activity that can lead to falling or getting hit in the face.

When the bones are stable the orthodontist can resume aligning the teeth for a perfect fit. Typically, this takes about 6 more months. The teeth are placed into retainers to maintain stability of the bone and the bite.
Thus the total treatment time once growth is completed takes on average 18 – 24 months of comprehensive care.

Are there any side effects?

You will have some swelling and bruising after the operation. This will rapidly begin to subside over the first 2 – 3 weeks. For operations on the lower jaw it is fairly common to have some numbness of the lower lip for some weeks or months afterwards. In a very small number of cases a residual area of numbness will remain. This numbness will not affect movement of your lip, only the feeling in it, in a similar way to an injection at the dentist.

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