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%)