Genesis and characteristics of an odontogenic keratocyst

A cyst is essentially a sac of membranous tissue that can occur anywhere in the body. They normally contain fluid, but other substances can also be found inside them on occasion. Cysts are benign and not cancerous growth. There are many kinds of cysts. They include epidermoid cyst, sebaceous cyst, pilonidal cyst, ovarian cyst, chalazion of the eyes, popliteal cyst and pilar cyst amongst others.

Varieties of common cystic lesions

Treatment of cysts includes excision and careful enucleation of the cystic lesion including the membranous lining of the cyst. Any remnants left behind during enucleation can lead to recurrence of the cyst. Care has to thus be taken to ensure complete removal of the contents of the cystic cavity. Some of the more common cysts include the sebaceous cyst, the chalazion, and the epidermoid cyst. Cysts can turn painful when they occur in a confined space or get infected.

Epidermoid cysts are slow growing cysts that are the result of keratin buildup under the skin. They can get infected easily as they are very close to the surface of the skin. Sebaceous cysts occur when sebum glands get clogged leading to a buildup of sebum. This too can get infected easily. Surgical excision is the treatment of choice for both these cysts.

A pilonidal cyst occurs at a hair follicle and is said to occur due to a combination of hormonal changes, friction or prolonged pressure to that region. It can be quite painful and there is a foul smelling discharge from the cyst. A hair follicle is also present in association with the cyst. Treatment is curettage and enucleation along with removal of the associated hair follicle.

Etiology and pathogenesis of odontogenic keratocyst

An odontogenic keratocyst is a very rare benign developmental cyst that is very aggressive. It results in extensive destruction of the bone. It is most commonly seen in the posterior mandibular region in the third decade of life. The PTCH1 gene, which leads to the occurrence of odontogenic keratocyst has also been linked to the occurrence of ovarian cysts and ovarian cancer. Differential diagnoses for odontogenic keratocysts can include epidermoid cysts though these are completely different in their origin.

Recommended treatment protocol for odontogenic keratocysts

Treatment of the odontogenic keratocyst involves meticulous resection to completely remove the lesion followed by reconstruction of the jaw with bone grafting. Implant surgery for the placement of dental implants is performed after full bony consolidation of the bone grafts to complete full oral rehabilitation for the patient. This is the treatment protocol that is recommended by the American Association of Oral and Maxillofacial Surgeons. The patients thus properly cared for can go on to lead a completely normal life.

Use of dental implants for oral rehabilitation from destructive jaw lesions

The advent of dental implant treatment has enabled complete rehabilitation patients with odontogenic keratocyst. Implants enable replacing missing teeth. Success rates are extremely high for patients rehabilitated with dental implants. This is because dental implants mimic tooth roots and are able to bear occlusal loads that are borne by natural teeth.

Before dental implant treatment became a part of routine surgical protocol, postsurgical dental rehabilitation was through the use of removable dentures. This was highly unsatisfactory for the patient. The patient faced a lot of difficulty with both chewing and speech.

Dental implants have enabled the complete rehabilitation of both the upper and lower jaws. Proper maintenance of dental implants aided by following instructions of the implant surgeon meticulously is essential for the success of dental implant treatment.

Patient develops pain and swelling in the left posterior mandibular region

The patient is an 18-year-old female who had slowly developed a soft tissue swelling of the left posterior mandible with pain for the last six months. She had consulted a local dentist who noticed that the patient’s left third molar was missing from the oral cavity. Suspecting the swelling to be a dentigerous cyst, he had referred the patient to our hospital for management. Our hospital is a renowned center for jaw reconstruction surgery. Implants will need to be placed to complete oral rehabilitation after jaw reconstruction surgery.

Examination of the patient at our hospital with subsequent investigations

The patient presented at our hospital for management of the pain and swelling in her left posterior mandibular region. Dr SM Balaji, an oral and maxillofacial surgeon and jaw reconstruction surgeon in Chennai, examined the patient and ordered imaging studies and a biopsy of the lesion. The biopsy results returned as odontogenic keratocyst.
Imaging studies revealed a radiolucent lesion in relation to the left mandibular molars and a horizontally impacted third molar. Treatment planning for the management of the odontogenic keratocyst was explained to the patient in detail. She was advised to undergo cyst removal surgery and was in total agreement with surgical management of the lesion.

Bone graft harvested from the patient for jaw reconstruction

Under general anesthesia, rib grafts were first harvested from the patient. The rib grafts will be used to reconstruct the jaw after resection of the odontogenic keratocyst. A Valsalva maneuver was then performed to ensure that there was no perforation into the thoracic cavity. Following this, the incision was then closed in layers with sutures.
Resection of the odontogenic keratocyst from the left posterior mandible.

A mucogingivoperiosteal flap was raised in the left posterior mandibular region. This exposed the area of the odontogenic keratocyst. The cystic lesion was exposed and then completely resected. Great care was taken to ensure that there were no cystic remnants left behind in the bony cavity. The rib grafts were then carefully shaped to fit into the bony defect left behind by the lesion.

Titanium screws were used to fix the rib grafts into the bony defect in the jaw to reconstruct the jaw. Once adequate jaw reconstruction had been achieved with the rib grafts, the flap was then closed with sutures. The healing process along with bone remodeling of the grafts to merge in with the mandibular bone takes up to 6-8 months. Implants should only be placed after this is complete to ensure good long term results.

Placement of dental implants for complete oral rehabilitation for the patient

Once adequate consolidation of the bone grafts has been achieved, the patient will return to our hospital again for placement of dental implants. A period of six months will be given following dental implant surgery to allow for complete osseointegration of the dental implants with the mandibular bone. Complete oral rehabilitation of the patient would then be done with placement of tooth coloured crowns to the dental implants. Zirconium crowns or ceramic crowns offer great functional and esthetic results to complete the patient’s rehabilitation.

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