Introduction
A dentigerous cyst, also known as a follicular cyst, is a type of odontogenic cyst that occurs in the jawbone. It is the second most common type of jaw cyst, following the periapical (radicular) cyst. Dentigerous cysts are most commonly associated with impacted third molars (wisdom teeth) or maxillary canines.
Causes and Pathogenesis
The exact cause of dentigerous cysts is not fully understood, but it is believed to result from the accumulation of fluid between the tooth and the surrounding bone. This accumulation of fluid can lead to the formation of a cystic cavity, which can expand and cause damage to the surrounding bone and teeth.
Epidemiology
• Most commonly affects people in their 2nd or 3rd decade of life.
• More frequent in males than females.
• Mandibular third molars are the most commonly involved teeth, followed by maxillary canines.
Clinical Features:
• Asymptomatic: Many dentigerous cysts are discovered incidentally during routine dental X-rays, as they may not cause any noticeable symptoms.
• Swelling: As the cyst grows, it can cause a noticeable swelling in the jaw, particularly in the area of the impacted tooth.
• Displacement of Teeth: The cyst can push adjacent teeth out of alignment or cause them to erupt ectopically.
• Gaps Between Teeth: If the cyst displaces teeth, gaps may appear between them.
• Tooth Sensitivity: Some individuals may experience sensitivity in the affected teeth.
• Palpable Lump: In some cases, a small, hard lump may be felt in the gum where the tooth is impacted.
• Pain (in some cases): While often painless, dentigerous cysts can cause pain if they become inflamed or infected.
• Jaw Expansion: Very large cysts can cause noticeable expansion of the jawbone.
• These cysts are commonly single lesions. Bilateral and multiple dentigerous cysts are very rare although they have been reported. Bilateral or multiple dentigerous cysts have been reported in Maroteaux-Lamy syndrome, cleidocranial dysplasia and Gardner's syndrome. In the absence of these syndromes, the occurrence of multiple dentigerous cysts is rare. Sometimes multiple dentigerous cysts are suggested to be induced by prescribed drugs. The combined effect of cyclosporine and a calcium channel blocker is reported to cause bilateral dentigerous cyst

Radiographically
The diagnosis of a dentigerous cyst is typically made based on a combination of clinical and radiographic findings. Radiographic examination, such as panoramic radiographs or cone beam computed tomography (CBCT), can help to identify the cyst and its relationship to surrounding structures
On radiographic examination, a dentigerous cyst appears as a unilocular radiolucent area that is associated with just the crown of an unerupted tooth and is attached to the tooth at the cementoenamel junction. The radiolucency is generally well defined and well corticated, but a secondarily infected cyst may display ill-defined borders. However, a large dentigerous cyst may give the impression of a multilocular process due to the persistence of bone trabeculae within the radiolucency

The cyst-to-crown relationship presents several radiographic variations which are
1. Central variant: This is the most common variant in which the cyst surrounds the crown of the tooth .
2. Lateral variant: This variant is usually associated with a mesioangular impacted mandibular third molar that is partially erupted. The cyst develops laterally along the root surface and partially surrounds the crown
3.Circumferential variant: The cyst surrounds the crown and extends for some distance along the root surface so that a significant portion of the root appears to lie within the cyst.
Treatment
Treatment typically involves surgical removal of the cyst along with the associated impacted tooth. Options include:
Enucleation: Complete surgical removal of the cyst.
Marsupialization: Creating a surgical window to decompress the cyst, often used when preserving adjacent structures is important.

Differential diagnosis
When small, it is difficult to differentiate a dentigerous cyst from a large but normal dental follicle ; Generally, any pericoronal radiolucency that is greater than 3–4 mm in diameter is considered suggestive of cyst formation.
When the cyst is larger, the differential diagnosis include:
-periapical cyst (radicular cyst)
-aneurysmal bone cyst
- uni-cystic ameloblastoma
-odontogenic keratocyst
- adenomatoid odontogenic tumor