Effects of occlusal attrition and continuous eruption on odontometry of rat molars.

Recurrent reports by others of posteruptive dimensional increase of the crowns of rat molar teeth were analyzed in the context of our present study of occlusal attrition, continuous eruption and alteration of the occlusal planes of rat maxillary molar teeth with age. Marked attrition of the anatomical crowns occurs, together with a considerable continuous eruption that increasingly brings the markedly convex mesial root of the maxillary first molar into the clinical crown. Further, a slight change in occlusal plane occurs. Previous workers used standardized planes of orientation and of registration prior to measurement, which masked the phenomena mentioned above. They thus mistakenly reported increased coronal dimensions.