Signs and Symptoms
- Periapical cysts begin as asymptomatic and progress slowly
- Subsequent infection of the cyst causes swelling and pain
- The cyst swells to a round hard protrusion initially
- The body resorbs some of the cyst wall, leaving a softer accumulation of fluid
- Inflammation and infection of the pulp cause dental caries and necrosis
Complications
- Expansion of the cyst causes erosion of the floor of the maxillary sinus
- Percussion test on affected teeth causes shooting pain
- Complications often clinically diagnostic of pulpal infection
- Increased pressure and size of the cyst
- Shooting pain and bone resorption caused by cyst growth
Causes and Mechanisms
- Dental cysts are usually caused by root infection and tooth decay
- Bacteria reach the pulp, causing infection and pulpal necrosis
- Epithelial rests of Malassez release toxins at the apex of the tooth
- Inflammatory response leads to periapical inflammation
- Pressure over the bone causes resorption and cyst growth
- Periapical cysts develop due to an inflammatory stimulus in 3 stages
- Initial stage: Epithelial cells from the rests of Malassez become stimulated
- Cyst development stage: Epithelial cells form strands and surround abscess or foreign body
- Cyst growth stage: Fluid flows into the cavity, increasing pressure and size
- Debate exists regarding the definitive mechanism of cyst growth
Diagnosis
- A non-vital tooth is necessary for the diagnosis of a periapical cyst
- Oral examination includes palpation of surrounding structures and bone damage
- Radiology, such as X-rays or a 3-D cone beam scan, confirms diagnosis
- Circular or ovoid radiolucency surrounding the root tip indicates a cyst
- Histopathology shows stratified squamous epithelium and fibrous capsule
Treatment and Epidemiology
- Complete removal of infected tissue, including cyst wall epithelium, to prevent relapse
- Root canal treatment for unsuccessful previous therapy
- Removal of necrotic pulp and inflamed tissue
- Proper sealing of canals and fitting crown for healing under uninfected conditions
- Surgical options for previously treated teeth: cystectomy and cystostomy
- Periapical cysts comprise approximately 75% of oral region cysts
- Ratio of individuals diagnosed with periapical cysts: 3:2 male to female
- Most common in individuals between 20 and 60 years old
- Periapical cysts occur worldwide
- Types of periapical cysts: apical (70%), lateral (20%), residual (10%)
Commonly known as a dental cyst, the periapical cyst is the most common odontogenic cyst. It may develop rapidly from a periapical granuloma, as a consequence of untreated chronic periapical periodontitis.
| Periapical cyst | |
|---|---|
| Other names | Radicular cyst, inflammatory cyst |
 | |
| CT scan through head showing a right periapical cyst | |
| Specialty | Dentistry  |
Periapical is defined as "the tissues surrounding the apex of the root of a tooth" and a cyst is "a pathological cavity lined by epithelium, having fluid or gaseous content that is not created by the accumulation of pus."
Most frequently located in the maxillary anterior region, the cyst is caused by pulpal necrosis secondary to dental caries or trauma. Its lining is derived from the epithelial cell rests of Malassez which proliferate to form the cyst. Such cysts are very common. Although initially asymptomatic, they are clinically significant because secondary infection can cause pain and damage. In radiographs, the cyst appears as a radiolucency (dark area) around the apex of a tooth's root.
