Dental cysts are abnormal, fluid-filled sacs that develop within the jawbone or the soft tissues of the mouth. These lesions are generally benign, but their presence indicates an underlying issue and they have the potential to cause significant damage if left untreated. Understanding the origins of these formations—whether from infection or developmental errors—is the first step toward effective management and maintaining long-term oral health. Many of these growths are treatable, especially when detected early through routine dental examination.
Anatomy of a Dental Cyst
A dental cyst is classified as a pathological cavity defined by an epithelial cell lining. This lining separates the cyst’s contents from the surrounding bone or tissue. This structure distinguishes a true cyst from a simple dental abscess, which is an acute, pus-filled pocket resulting from a bacterial infection but lacking an organized epithelial wall.
The contents generate internal hydrostatic pressure, which drives the cyst’s expansion. This constant, slow pressure causes the surrounding jawbone to resorb, allowing the cyst to grow without immediate pain or noticeable symptoms. Because of this gradual, expansive growth, a cyst can erode substantial bone and displace teeth over months or years before detection. The epithelial lining originates from remnants of the tooth-forming tissues, known as odontogenic epithelium.
Cysts Caused by Infection or Injury
The most common type of dental cyst, the periapical or radicular cyst, arises directly from inflammation and infection. This inflammatory cyst forms at the apex, or tip, of a tooth root that has experienced pulp necrosis. This occurs most frequently due to deep, untreated dental decay that allows bacteria to penetrate the pulp chamber and infect the surrounding periapical tissues.
The bacterial toxins stimulate dormant epithelial cells called the Rests of Malassez, which are remnants of the tissue that originally formed the tooth’s root. These stimulated cells proliferate to form the epithelial lining of the cyst. A radicular cyst may also form following trauma to a tooth that causes the death of the dental pulp without immediate symptoms.
If a periapical cyst is not fully removed when the associated tooth is extracted, the epithelial lining can remain in the bone, leading to a residual cyst. These inflammatory causes link the formation of the cyst back to a pre-existing dental problem, such as decay or a failed root canal treatment, requiring a focused approach to resolve the source of the initial infection.
Cysts Resulting from Tooth Development
In contrast to inflammatory cysts, some dental cysts originate from errors during tooth development, independent of decay or infection. The dentigerous cyst, also known as a follicular cyst, is the second most common type and forms around the crown of a tooth that has failed to erupt. It develops because fluid accumulates between the crown of the unerupted tooth and the reduced enamel epithelium that covers it.
Dentigerous cysts most often involve impacted wisdom teeth, but they can also affect canines or other teeth trapped within the jawbone. Although developmental, these cysts can still cause significant damage, pushing teeth out of alignment and destroying substantial portions of the jawbone.
Another developmental type is the Odontogenic Keratocyst (OKC), which has a unique and aggressive nature. The OKC originates from remnants of the dental lamina, the embryonic tissue responsible for initiating tooth formation. This specific type of cyst is known for its tendency to grow extensively within the bone and has a significantly higher rate of recurrence after surgical removal compared to other types. The presence of multiple OKCs can sometimes be associated with a genetic condition known as Nevoid Basal Cell Carcinoma Syndrome.
Diagnosis and Treatment Approaches
Dental cysts are frequently asymptomatic and are often discovered incidentally during routine dental X-rays, appearing as a dark, well-defined area of bone loss. When symptoms occur, they may include localized swelling, pain if the cyst becomes infected, or the displacement or loosening of nearby teeth. Advanced imaging, such as a Cone Beam Computed Tomography (CBCT) scan, is often used to determine the size and relationship of the cyst to surrounding nerves and teeth.
A definitive diagnosis requires a biopsy, where a tissue sample of the cyst lining is examined under a microscope to rule out potentially more aggressive or neoplastic growths. The primary treatment for most cysts involves surgical removal, a procedure called enucleation, where the entire cyst lining is separated from the surrounding bone. For very large cysts, a two-stage approach called marsupialization may be used first, which involves opening the cyst to the oral cavity to decompress it and allow it to shrink before final surgical removal. Treatment may also include root canal therapy to save the associated tooth or its complete extraction.