Complementary response to inflammation
Chemical reaction with Interleukin and Prostaglandin

Mechanisms
Periapical cysts develop due to an inflammatory stimulus in 3 stages:
Initial stage: Epithelial cells from the rests of Malassez at the apex of the roots of a non-vital tooth (one where the nerve and blood supply in the tooth have degenerated and no longer exist) become stimulated due to the bodys inflammatory response to bacterial endotoxins infecting the pulp or as a direct response to necrotic pulp tissue, therefore re-entering the growth phase. Bacterial byproducts then are able to seep into the periapical region through the infected pulp. Cyst development stage:  Epithelial cells form strands and are attracted to the area which contains exposed connective tissue and foreign substances. Several strands from each rest converge and surround the abscess or foreign body. Cyst growth stage: Fluid flows into the cavity where the forming cyst is growing due to the increased osmolality of the cavity in relation to surrounding serum in capillaries. Pressure and size increase.The definitive mechanism by which cysts grow is under debate; several theories exist. Biomechanical theory
Pressure and concentration differences between the cystic cavity and the growth surroundings influence fluid movement into the cyst, causing size increase. Biochemical theories
a. Collagenase (breakdown of collagen) in the jaw bone leads to bone degeneration, providing room for cysts to develop. Substances released by the bodys immune system as a result of the connective tissue breakdown, such as cytokines and growth factors, contribute to the mobilization and proliferation of epithelial cells in the area. b.
This type of treatment is more ideal for small cysts. A cystostomy is recommended for larger cysts that compromise important adjacent anatomy. The cyst is tamponaded to allow for the cyst contents to escape the bone. Over time, the cyst decreases in size and bone regenerates in the cavity space. Marsupialization could also be performed, which involves suturing the edges of the gingiva surrounding the cyst to remain open. The cyst then drains its contents and heal without being prematurely closed. The end result is the same as the cystostomy, bone regeneration. For both a cystostomy and marsupialization, root resectioning may also be required in cases where root resorption has occurred. Epidemiology
Periapical cysts comprise approximately 75% of the types of cysts found in the oral region. The ratio of individuals diagnosed with periapical cysts is 3:2 male to female, as well as individuals between 20 and 60 years old. Periapical cysts occur worldwide. Types of Periapical cysts:
Apical: 70%
Lateral: 20%
Residual: 10%

References


== External links ==