Aim: To evaluate occlusal wear after comprehensive orthodontic treatment. Methods: Consecutive pre- and posttreatment dental casts of 30 patients who had received orthodontic treatment with stainless steel fixed appliances in both dental arches at the postgraduate clinic of Aristotle University of Thessaloniki were digitized by means of a three-dimensional CT scanner. The final sample consisted of 1,256 individual teeth (628 reference-free 3D superimpositions). The data were statistically assessed. Five randomly selected pairs of pre- and posttreatment casts were measured twice; the results were compared by paired t test. The magnitude of the method’s error was 0.188 mm3 (P =.229). Results: After orthodontic treatment, almost all examined teeth had decreased in volume. The mean decrease was 1.03 mm3 per tooth (P < .001). Treatment duration greater than 30 months was associated with a significant increase in occlusal wear (P < .001). No significant differences were found between extraction and nonextraction treatments, males and females, or different groups of teeth or malocclusions. Conclusion: There seems to be a relationship between orthodontic treatment and occlusal wear, which deserves serious attention and further investigation. Orthodontics (Chic) 2011;12:122–129.

Key words: occlusal wear, 3D CT scanner, tooth morphology, attrition, cusps