Purpose: To assess the relationships between occlusal tooth wear and occlusal conditions, chewing side preference, and occlusal guidance scheme. Materials and Methods: A total of 257 Chinese adult dental school patients were categorized according to a hierarchical functional classification system. Occlusal tooth wear was assessed using a modified Smith and Knight index. Occlusal tooth wear index (OTWI) scores were analyzed using multivariate regression models, including four specific occlusal conditions (≥ 10 teeth in each arch, complete anterior regions, sufficient premolar regions, and sufficient molar regions) adjusted for age and sex. Results: Occlusal tooth wear was observed in all participants; older participants and men had significantly higher mean OTWI scores. The occlusal condition of having fewer than 10 teeth in each arch was significantly associated with occlusal tooth wear; participants with fewer than 10 teeth in each arch had higher mean OTWI scores in anterior and premolar teeth. OTWI scores for the different tooth types were highly correlated with chewing side preference. OTWI scores for the molar region (including third molars) were significantly higher at the preferred chewing side. The same effect was seen for OTWI scores of all teeth combined. OTWI scores were not associated with occlusal guidance scheme. Conclusions: The occlusal condition of having fewer than 10 teeth in each arch appears to be a risk factor for increased occlusal tooth wear. Occlusal wear was more severe at the chewing side. Occlusal tooth wear was significantly associated with the nondental factors of age and sex. Int J Prosthodont 2014;27:54-60. doi: 10.11607/ijp.3642