The periapical tissues undergo changes during the progression of dental caries. In case of extensive bacterial invasion involving the pulp, apical periodontitis is typically the body's host response. In response to the injury, chemotaxis occurs. After the initiation of inflammation, macrophages, leukocytes and lymphocytes enter and comprises the bulk of periodontitis. Necrotic tissue within the pulp chamber and canals provide nutrients for pathogenic bacteria to grow and form a periapical lesion. Endodontic instruments, materials as well as food debris may also be the cause of persistent periapical lesions. The time of healing is variable and may range from 3 months to 4 years. The assessment of periapical healing is done by using radiographs or Cone Beam Computed Tomography (CBCT). Reason: To assess the time period for the healing of periapical lesions after Root Canal Treatment because a number of controlling factors decide the time of healing.
