Abstract The aim of the present study was to determine the progression rate of periodontal disease in patients treated for localized or generalized mild to moderate adult periodontitis. 52 patients with a mean age of 53.7 years (S.D. 12. 6 years) were instructed in optimal home care procedures and exposed to initial periodontal therapy, before reconstructive therapy was initiated. Following completion of the prosthetic procedures, supportive therapy was offered to a limited extent and maintenance visits were irregularly scheduled corresponding to traditional dental care. Clinical periodontal parameters from 4 sites per tooth were assessed at the initial examination, at the time of reevaluation after initial therapy and at the re‐examination after 8‐years. Full sets of intraoral radiographs from the initial and the 8‐year re‐examination were analyzed with respect to changes in the radiographic alveolar bone height as a % of the total tooth length. As the result of the home care instructions, the mean plaque index (plaque control record) amounted to 21% at the end of initial periodontal therapy. 8 years later, the re‐examination revealed a mean plaque index of 49% and a mean gingival bleeding index of 24%. At the initial examination, the 52 patients presented with an average of 18.7 teeth. During treatment. 26 teeth were sacrificed and 19 teeth were lost over the 8 years of supportive therapy. Bicuspids were the most frequent teeth to be lost over the observation period. As a result of initial therapy, the mean pocket probing depths decreased significantly. However, after 8 years, only minor differences were found when compared to the initial examination. At all examinations, the buccal and the oral aspects presented with shallower pockets compared to the interproximal sites. The comparison of the changes in the mean probing attachment levels over the observation period at mesial, buccal, distal and oral sites revealed a gain in clinical attachment after initial therapy and a mean loss of attachment ranging from 0.48 mm to 0.79 mm from the initial to the re‐examination after 8 years. The buccal aspects demonstrated the highest mean clinical attachment loss followed by the oral sites. The radio‐graphic assessment of the changes in the mean alveolar bone height revealed a statistically significant, but a clinically insignificant, loss of alveolar bone height of less than 2% of the tooth length. The patient population was grouped into 21 patients seeking supportive therapy less than once per year over 8 years. 14 patients having had one maintenance visit per year and 17 patients who were recalled more than once per year. With respect to the distribution of the number of sites with different changes in probing attachment level, no statistically significant difference between the groups was observed. When frequency analyses of the radiographically assessed changes in the alveolar bone height were performed, similar results were obtained. With the parameters and the statistical methods applied in this study, no significant influence of the age nor the recall frequency on the progression rate of periodontal disease could be detected in this group of patients presenting initially with mild to moderate adult periodontitis. Recall visits corresponding to conventional dental care did not prevent further loss of attachment, resulting in a deterioriation of the periodontal conditions compared to the results achieved after initial therapy and in 45 out of 52 patients compared to the baseline examination.