Mandibular prognathism Correction (Long Lower jaw) Surgery BSSO Bilateral Sagittal Split Osteotomy

Mandibular prognathism arising from an excessively large mandible

When the lower jaw is disproportionately larger than the upper jaw in size, this condition is known as mandibular prognathism. When the upper jaw is normal in size and the lower jaw is disproportionately larger than normal, it is called true mandibular prognathism. Correction of this condition involves reduction in the size of the mandible. This is achieved through surgical correction.

Benefits from the development of modern medicine and dentistry to humanity

Modern dentistry has come to the aid of many conditions that caused great suffering in the past. There was a time when even the most minor of dental ailments could even turn life threatening. Alveolar abscesses that are so easily controlled today through the use of antibiotics and root canal treatment could lead to the death of the individual 150 years ago.

Mandibular prognathism during olden days would have caused an extreme degree of distress to the individual with regards to eating and speech. Anterior crossbite is present in mandibular prognathism. Difficulty with chewing food would have caused intake of insufficient nutrition that could lead to malnutrition.

Historical occurrence of mandibular prognathism

Mandibular prognathism was a feature that was common among the von Habsburgs of Austria. The Habsburgs were the dynasty that ruled the Austro-Hungarian empire before World War I. Most of the male members of this dynasty demonstrated a marked mandibular prognathism. A prognathic mandible is also called a Habsburg jaw or lantern jaw.
The Habsburg jaw was an extreme manifestation of mandibular prognathism because of many generations of inbreeding. What must have been present as mild mandibular prognathism in the first generation had become accentuated to an extreme degree through the inbreeding. It was so extreme in some of them that they were unable to chew food because of the prognathism. There was no treatment to correct jaw prognathism prior to the advent of modern dentistry.
Jaw deformities are a common occurrence in case of extensive inbreeding. Many breeds of dogs that are inbred to retain the bloodline exhibit severe jaw deformities. This is because inbreeding is against the laws of nature and is something that is unique to human beings.

Surgical technique used for correction of mandibular prognathism

A bilateral sagittal split osteotomy is performed to reduce the size of the mandible and bring it into correct alignment with the maxilla. An illusion of mandibular prognathism can occur when there is a retruded maxilla and a normal mandible. Correction of this condition is through forward movement of the maxilla through distraction osteogenesis. This corrects the relationship between the maxilla and mandible and brings the two jaws into correct alignment.

Surgeons advice diagnosis or treatment planning in several steps using various diagnostic protocols. They look for excessive wear of the teeth in the molar region. This surgery is contraindicated in patients who have undergone treatment for oral cancer as per the American Association of Oral and Maxillofacial Surgeons.

Patient with mandibular prognathism referred to our hospital for surgical correction

The patient is a young woman from Kurnool, Andhra Pradesh. She has had long standing problems with anterior crossbite due to mandibular prognathism. This had led to her feeling very self conscious because of the cosmetic aspect of her prognathism. She had always desired to undergo corrective jaw surgery for her problem.
Parents and patient referred to our hospital for surgical management

Her parents decided to seek the upper and lower jaws and teeth correction treatment advice from an oral surgeon in their hometown. She and her parents approached a local oral surgeon to seek the advice regarding the details about surgery. He said to them that this was not conducive for maintaining good oral health and referred them to Balaji Dental and Craniofacial Hospital for corrective orthognathic surgery. He explained to them that this is a specialty maxillofacial surgery center for jaw reduction surgery in India. Jaw reduction surgery requires extreme precision in measurements to achieve the best results.

Mandibular prognathism is a condition that is present in 0.35% of the Indian population. This condition completely alters the jaw line. Correction of this condition is done by jaw reconstruction surgeon in India. A bilateral sagittal split osteotomy is performed to reduce the size of the lower jaw and make it proportionate with the upper jaw.

Benefits of undergoing surgical correction of mandibular prognathism

It is common to see many people with mandibular prognathism who have not even considered the option of surgical correction. They have to be educated regarding the benefits of undergoing surgical correction of their condition. This would include improvement in speech and eating habits along with the improvement in esthetics. It is mostly those with pronounced functional disruption who voluntarily seek help for their condition.

Tooth extraction is never a part of this surgery as it is performed posterior to the tooth bearing section of the mandible. This can also be considered a cosmetic surgery or plastic surgery as it results in dramatic improvement in facial appearance of the patient. Soft tissues automatically mold themselves once this surgery is complete and there is no need to do any soft tissue correction as part of this surgery.

Initial examination and treatment planning explained to the patient and her parents

Dr SM Balaji, oral and maxillofacial surgeon, examined the patient and ordered radiographic studies. The patient had anterior and right-sided posterior crossbite. Presurgical planning was meticulously carried out on the patient. He explained that orthognathic surgery is performed for correction of this condition. The patient was in agreement with the treatment plan and consented to surgery.

Surgical correction of mandibular prognathism with very good results

Under general anesthesia, bilateral sagittal split osteotomy was performed. The anterior segment of the mandible was then positioned posteriorly to align correctly with the maxilla. Great care was taken to protect the exposed inferior alveolar nerve during this segment of the surgery. Intermaxillary fixation was then applied. This was followed by removal of a 5 mm wide piece of bone from the horizontal plane bilaterally followed by fixation of the two segments with plates and screws. Occlusion was checked again and maxilla and mandible were found to be in perfect alignment. Intermaxillary fixation was then removed and the patient was extubated and recovered uneventfully from general anesthesia.

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