OBJECTIVE To assess tooth-related factors contributing to tooth loss over a period of 10 years after completion of active periodontal therapy (APT). METHODS All patients who had received APT by the same experienced periodontist, 10 years before beginning the research, were recruited until 100 patients were re-examined. Examinations included, at the patient level: test for interleukin-1 polymorphism, compliance to supportive periodontal therapy (SPT), mean plaque scores during SPT; at the tooth level: assessment of baseline bone loss (type, amount), tooth type, furcation status and abutment status. Logistic multilevel regression was performed for statistical analysis. RESULTS Hundred patients with 2301 teeth at the baseline (completion of APT) were retrospectively examined. One hundred fifty-five teeth were lost over 10 years after APT. Logistic multilevel regression identified high plaque scores, irregular attendance of SPT and age as patient-related factors significantly accounting for tooth loss. Tooth-related factors significantly contributing to tooth loss were baseline bone loss, furcation involvement and use as an abutment tooth. However, in patients with regular SPT, 93% of teeth with 60-80% bone loss at the baseline, survived 10 years. CONCLUSIONS The following tooth-related risk factors for tooth loss were identified: baseline bone loss, furcation involvement, and use as an abutment tooth.