By "pathologic abrasion" is defined the excessive loss of the hard dental substance, which may lead to a total removal of the anatomic crown. This is one of most severe affections of ADM but also one of the best tolerated for a certain length of time. Four aspects of abrasion are frequently noted:--helicoidal abrasion--ad palatum abrasion;--horizontal abrasion;--keylock type abrasion. Excessive abrasion is due to bruxisme in most of the cases, and also to diet, but to a lesser extent. In most of the patients DVO is not modified because, as abrasion persists the continuous process of dental eruption, as well as of the alveolar processes develops. This is the reason for which it has been concluded that DVO should not be removed by prosthetic therapy in patients with extreme abrasion. The most simple solutions should be selected, avoiding complicated therapies because "the ideal treatment" is not always successful for a long time.