OBJECTIVE To examine whether there is an association between periodontal disease and each of root caries and coronal caries among adults (aged 35 and over), using a nationally representative sample of adults in England, Northern Ireland and Wales. METHODS In this cross-sectional study, data from the Adult Dental Health Survey 2009 were used. Adults aged 35 years or older who had periodontal and caries assessment were included. Two sets of negative binomial regression were conducted for each of coronal caries and root caries adjusting for periodontal diseases, dental visits, country, sex, age, education, job classification, oral hygiene and smoking. RESULTS Overall, 4738 were included in the analysis. Periodontal disease was significantly associated with each of coronal and root caries. In the fully adjusted model, those with PD/ LoA ≥ 4 mm had 1.03 rate ratio (RR) for coronal caries (95% CI: 1.01-1.05). In the model pertaining to root caries, the RR for those with periodontitis was 1.23 (95% CI: 1.16-1.30). Smoking, sex, age and oral hygiene were the variables that showed a consistent and significant association with coronal and root caries. CONCLUSIONS Individuals with periodontal diseases appeared to be at higher risk of coronal and root caries. While root exposure could be a plausible explanation for the relationship between periodontitis and root caries, the association with coronal caries could be attributed to the irritation of carious cavities, or common risk factors such as poor oral hygiene, or co-occurrence of different health risk behaviours related to both caries and periodontitis and socioeconomic conditions.