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%)