The amount of enamel wear on the antagonist occlusal surfaces caused by self-glazed zirconia crowns was compared with that caused by contralateral natural teeth. Thirteen self-glazed zirconia crowns were placed in situ. The impressions of self-glazed zirconia crowns, their antagonists and the control teeth were taken and scanned at baseline and 6-month follow-up. The patients were divided into two groups, the self-glazed crowns in one group were subjected to a large amount of grinding with well polishing (LaP group, n=7), while the other group required a little amount of grinding with well polishing (LiP group, n=6). Statistics were analysed by two-sided paired Student's t-tests to a significance level of p<.05. The results revealed that the maximum and mean enamel wear significantly different between the antagonists of self-glazed crowns and the control teeth (p<.05). Increased amount of enamel wear was found in LaP group (p<.05). The self-glazed zirconia crowns caused more enamel wear of antagonists than natural teeth after 6 months. Occlusal adjustment and polishing were considered as possible confounders which affected wear behaviour.