Purpose: To record periodontal treatment needs in a randomised sample and evaluate the association between body mass index (BMI) and periodontal treatment needs, as well as the association between diabetes, smoking, BMI and periodontal treatment needs. Materials and Methods: The study sample comprised 633 patients aged 18 to 85 years visiting an outpatient clinic. Body mass index (BMI) and periodontal status were recorded. Demographic data including gender, year of birth, smoking habits and medical history were collected from each patient. Results: 216 subjects (36%) were overweight, while 188 subjects (31.3%) were obese. CPITN (Community Periodontal Index of Treatment Needs) scores of 2 and 3 (minimal to moderate periodontal treatment needs) were widespread among this population (68.2%). Using model-based clustering, the total sample of 600 subjects was divided into four clusters of 202, 241, 111 and 46 subjects. Conclusion: The periodontal treatment needs of the sample were generally minimal to moderate, with only a weak association between the BMI and treatment needs. However, diabetics, smokers and older subjects classified as overweight or obese needed moderate to complex periodontal treatments. Schlagwörter: body weight, diabetes, periodontitis, risk factors, risk indicators