Odontogenic keratocyst (OKC) is a type of cyst that forms in the jawbone and is known for its aggressive behavior and tendency to recur after treatment. The primary cause of OKC is related to the remnants of the dental lamina, which are embryonic tissues involved in tooth development. These remnants can persist in the jawbone after tooth formation and, under certain conditions, start proliferating abnormally, leading to the formation of the cyst.
The dental lamina is a band of epithelial tissue that appears early in tooth development and gives rise to the enamel organ, which eventually forms the enamel of teeth. Normally, after teeth develop, the dental lamina breaks down and disappears. However, some epithelial cells can remain trapped in the jawbone or soft tissues. These residual cells are the origin of odontogenic cysts, including the odontogenic keratocyst.
Several factors may contribute to the activation and growth of these epithelial remnants into an OKC:
– **Genetic mutations and syndromes:** One well-known association is with nevoid basal cell carcinoma syndrome (also called Gorlin syndrome), a genetic disorder characterized by multiple basal cell carcinomas, skeletal abnormalities, and a high incidence of multiple OKCs. In this syndrome, mutations in the PTCH1 gene, which is part of the Hedgehog signaling pathway, lead to abnormal cell growth and cyst formation. This genetic link explains why some individuals develop multiple OKCs at a young age.
– **Cellular behavior:** The epithelial lining of OKCs has a unique characteristic compared to other cysts. It tends to grow rapidly and can infiltrate surrounding bone, which contributes to the cyst’s aggressive nature. The cyst lining produces keratin, a protein that accumulates inside the cyst cavity, causing it to expand.
– **Local factors:** Trauma, inflammation, or irritation in the jaw area might stimulate the dormant dental lamina cells to proliferate abnormally. Although these factors are not definitive causes, they may act as triggers in susceptible individuals.
– **Developmental origin:** OKCs are considered developmental cysts because they arise from tooth-forming tissues rather than from inflammatory processes. This developmental origin explains their occurrence mostly in the jawbones, particularly the posterior mandible (lower jaw), where dental lamina remnants are commonly found.
– **Molecular and cellular mechanisms:** Research has shown that the epithelial cells in OKCs express certain proteins and growth factors that promote cell proliferation and inhibit normal cell death (apoptosis). This imbalance allows the cyst to grow unchecked. Additionally, the cyst wall contains satellite cysts or daughter cysts, which can lead to recurrence after surgical removal if not completely excised.
In summary, the cause of odontogenic keratocyst is primarily the abnormal proliferation of residual dental lamina epithelial cells in the jawbone. This process is influenced by genetic factors, especially in syndromic cases, and by local environmental triggers. The cyst’s aggressive growth and potential for recurrence are due to its unique cellular characteristics and molecular behavior. Understanding these causes helps guide effective diagnosis and treatment strategies to manage OKCs and reduce their recurrence risk.
