[Does the alveolar process of the maxilla always disappear after tooth loss?].

The existence of the alveolar process depends on the development of teeth. In edentulous maxillae, the alveolar process disappears in general in the region of incisives, canines and eventually premolars, but it persists in over 80% of cases in the region of molars. The persistence of the alveolar process correlates with the pneumatisation of the alveolar process by the alveolar recess of the maxillary sinus. The sinus may invade the whole alveolar process or only part of it so that in its lower part a thicker bone layer persists. Very rarely the alveolar process disappears completely with the loss of teeth. The deepest recess of the maxillary sinus corresponds to the level of the zygomatic process i.e. to the region of the first and second molar teeth.