Inflammatory bowel disease (IBD) may be associated with oral diseases, but few relevant studies have been reported in China. This study aimed to compare the prevalence, severity and extent of dental caries and periodontal disease in Chinese IBD patients and healthy controls.In this cross-sectional study, questionnaires and oral examinations were completed for 389 IBD patients [265 with Crohn's disease (CD) and 124 with ulcerative colitis (UC)] and 265 healthy controls based on the established criteria of the World Health Organization. Tobit regression, multiple linear regression and logistic regression were performed to analyse the data.After adjusting for confounders, the decayed, missing and filled surfaces indices were significantly increased in the CD and UC patients compared with those in the controls (P < 0.001). Patients with CD [odds ratio (OR) = 4.27, 95% confidence interval (95% CI): 2.63-6.95, P < 0.001] and UC (OR = 2.21, 95% CI: 1.24-3.94, P = 0.007) had significantly higher risks of dental caries than controls. Significantly higher percentages of sites with probing pocket depth ≥ 5 mm and clinical attachment loss ≥ 4 mm were observed in CD and UC patients compared with controls (P < 0.001). A fully adjusted model revealed that CD and UC were risk indicators for periodontitis (OR = 4.46, 95% CI: 2.50-7.95, P < 0.001; OR = 4.66, 95% CI: 2.49-8.71, P < 0.001, respectively). No significant differences in dental caries and periodontal disease were observed between the CD and UC patients.Chinese IBD patients have a higher prevalence, severity and extent of dental caries and/or periodontal disease than controls, and require oral health education and multidisciplinary treatment.