A dental cyst is a fluid-filled sac, typically benign, that forms within the jawbone or soft tissues of the mouth, often near tooth roots. It is a closed cavity with a distinct membrane, developing abnormally and containing fluid or semi-liquid contents.
Understanding Dental Cysts
Dental cysts generally grow slowly and may not cause noticeable symptoms initially. Early detection is challenging without routine dental X-rays due to this asymptomatic period. As a cyst expands, it can cause discomfort, pain, or swelling. Untreated cysts can lead to bone destruction, displacement of adjacent teeth, or jaw fractures if the bone weakens, and can also become infected, transforming into painful abscesses. Proper diagnosis is necessary.
Causes from Infection and Inflammation
One of the most frequent causes of dental cysts is chronic infection or inflammation, which often originates from a compromised tooth. These are known as periapical or radicular cysts, forming at the tip of a tooth’s root.
When dental decay (caries) is left untreated, bacteria can penetrate the tooth’s outer layers and infect the dental pulp. This infection can lead to pulp necrosis, meaning the nerve inside the tooth dies.
Bacteria from the infected pulp can spread to the bone around the tooth’s root, stimulating an inflammatory response. The body forms a granuloma, a mass of immune cells and tissue, around the root tip to contain this infection. Over time, this inflammation can cause epithelial cell remnants to proliferate, forming a periapical cyst. Dental trauma or failed root canal treatments can also lead to similar inflammatory processes and cyst formation.
Causes from Tooth Development
Dental cysts can also arise from issues during tooth formation or eruption, distinct from infection-related causes. Dentigerous cysts, also known as follicular cysts, are a common developmental type. They form around the crown of an unerupted or impacted tooth, often wisdom teeth or maxillary canines, and are typically found in individuals aged 10 to 30. They develop from the dental follicle, the tissue sac surrounding a developing tooth. Fluid accumulation causes the follicle to expand, which can prevent the tooth from erupting properly.
Another developmental cyst is the odontogenic keratocyst (OKC), sometimes called a keratocystic odontogenic tumor due to its aggressive growth and high recurrence rate. OKCs originate from remnants of the dental lamina, the embryonic tissue responsible for tooth development. These cysts have a thin, friable wall and often contain cheesy, keratin-filled material. Though benign, their tendency to grow extensively along the jawbone and recur makes early detection and management important.
Other Contributing Factors
Beyond infection and tooth development, other factors can contribute to dental cyst formation, though they are generally less common. Some cysts arise from remnants of embryonic tissues that are not directly involved in tooth development. An example is the nasopalatine duct cyst, also known as an incisive canal cyst, which develops in the midline of the anterior maxilla near the incisive foramen. These cysts are believed to originate from persistent epithelial remnants of the nasopalatine duct, a structure that connects the oral and nasal cavities during fetal development.
Trauma can also lead to bone cysts, often called traumatic or simple bone cysts. These are considered pseudocysts because they lack an epithelial lining. While their exact cause is not fully determined, minor injury can lead to bleeding within the bone, forming a hematoma that results in a cyst-like cavity. Additionally, rare genetic syndromes, such as Nevoid Basal Cell Carcinoma Syndrome (Gorlin-Goltz syndrome) or Rubinstein-Taybi Syndrome, can predispose individuals to developing multiple odontogenic keratocysts or other types of cysts.