Diseases of pulp or periapical tissues

**Definition:** Dental pulp is that part of the tooth located in the centre of the coronal portion underneath dentin and composed of connective tissue, blood vessels and nerve endings. Periapical tissues are designated as those located at the tip of the tooth root surrounding the apical foramen.

**Long definition:** Apical foramen is the opening of the radicular pulp into the periapical connective tissue. The average size is 0.3 to 0.4 mm in diameter. There can be two or more foramina separated by a portion of dentin and cementum or by cementum only. Most infections spread through the apical foramen from the pulp to periapical tissue.