- It may be acute or chronic.
The chronic type may develop from either an acute apical abscess, a periapical granuloma, or a radicular cyst.
- The acute apical abscess is associated with a tooth with deep carious lesion. No radiographic evidence of changes in lamina dura or periapical bone. Widening of the periodontal ligament space. If there is further development of the abscess, a diffuse radiolucency in the periapical region of the affected tooth may be evident after a week.
- During the chronic phase: a diffuse periapical radiolucency of different size and often loss of the lamina dura at the apex.