A Cyst is a benign pathologic cavity filled with fluid, lined by epithelium, and surrounded by a connective tissue wall.

Types of the cysts:
1- Odontogenic Cysts, 2- Non-Odontogenic cysts, 3- Pseudocysts. 

Odontogenic Cysts: Radicular cyst, Residual cyst, Dentigerous cyst, Odontogenic Keratocyst (OKC), Lateral periodontal cyst, Calcifying odontogenic cyst and Buccal bifurcation cysts.
Non-Odontogenic Cysts: Nasopalatine cyst, Dermoid cyst, Nasolabial cyst and Developmental cysts
Pseudocysts:Traumatic bone cyst, Mucous Retention Cyst, Aneurysmal Bone Cyst and Stafne Bone Cyst.

Dentigerous cyst

The second most common odontogenic cyst. Develops around the crown of an unerupted permanent or supernumerary tooth. The dentigerous cyst is not thought to be neoplastic. Can grow very large and can move teeth. Most dentigerous cysts are asymptomatic, and their discovery is usually an incidental finding on radiography. Dentigerous cysts develop from follicular epithelium, and follicular epithelium has greater potential for growth, differentiation, and degeneration than the epithelium from which radicular cysts arise. These findings comprise most of the medical rationale for removal of impacted third molars with pericoronal radiolucencies; however, impacted teeth with small pericoronal radiolucencies (suggesting the presence of normal dental follicle rather than dentigerous cyst) may also be monitored with serial radiographic examination. Any increase in the size of the lesion should prompt removal and histopathologic examination. Any lesion that appears larger than a normal dental follicle indicates removal and histopathologic examination.

Odontogenic Keratocyst (OKC)
A cyst of tooth origin with an aggressive clinical behavior including a high recurrence rate. Mostly associated with impacted teeth.  The epithelium in OKC appears to have innate growth potential similar to some benign tumors. The odontogenic keratocyst (OKC) was first described in 18761 and named by Phillipsen in 1956. Peak occurrence in the 2nd and 3rd decades.  It has a high recurrence rate and is associated with the basal cell nevus syndrome. The majority of patients are in the age ranges of 20-29 and 40-59. Odontogenic keratocysts may occur in any part of the upper and lower jaw with the majority occurring in the mandible, most commonly in the angle of the mandible and ramus. Complete surgical removal is the treatment of choice.

Aneurysmal Bone Cyst
Aneurysmal bone cyst (ABC) is a solitary, expansile and erosive lesion of bone. It is found most commonly during the second decade and the ratio of female to male is 2:1. ABC's can be found in any bone in the body. More often, ABC's are thought to be a reactive process secondary to trauma or vascular disturbance. ABC's can be secondary to an underlying lesion such as non-ossifying fibroma, chondroblastoma, osteoblastoma, UBC's, chondromyxoid fibroma and fibrous dysplasia. ABC's are characterized by a rapid growth pattern with resultant bony expansion and facial asymmetry. Surgical management usually consists of surgical curettage or resection.

Traumatic Bone Cyst

The traumatic bone cyst (TBC) is an uncommon nonepithelial lined cavity of the jaws. The lesion is mainly diagnosed in young patients most frequently during the second decade of life. Some reports suggest that it is more common in males while others report equal distribution between males and females.  This condition does not represent a true cyst. Traumatic bone cavity is not unique to the jawbones; it is also described in the long bones and is known as a simple solitary bone cyst occurring mostly in the humerus or femur. They are usually unilocular and radiolucent, typically above the alveolar canal and in many cases with a scalloped superior border spreading between the roots of teeth. About 25% of the lesions present in the anterior mandible apical to the canine tooth and usually are round and unilocular, which can be mistaken for a periapical lesion leading to an unnecessary endondontic treatment. Clinically, surgeons almost always report an empty cavity at entrance; occasionally straw-colored fluid is described to be present. Blood clot is also present occasionally. The bony cavity is scraped to generate bleeding, which is considered the treatment of choice for this condition. Other reports demonstrate healing of traumatic bone cavity after injection of autogenous blood, after aspiration and after endodontic treatment. These lesions may spontaneously heal, but rarely.




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