The periodontal ligament is the structure that surrounds the roots of the teeth and connects them to the bone in which there are held. This is a highly vascular, loose cellular connective tissue that is organized into different groups. The most important bundles of fibers are called the principal fibers and include the alveolar crest fibers, the horizontal fibers, the oblique fibers and the apical fibers. The periodontal ligament has various functions including support, formation, nutrition and sensation. The alveolar bone supports the teeth; it arises when the tooth erupts in order to provide a bony union to the forming periodontal ligament, and gradually disappears when the tooth is lost. The spongy trabeculae of the alveolar bone are what absorb a large part of the pressure transmitted via the periodontal ligament, coming from the occlusal forces (1)(2)(4).