Results: The improvement of periodontal disease by open flap debridement in the older group was similar to that in the adult group, and no difference was found in the frequency of tooth loss in the 5 years after the start of SPT. However, the risk of recurrence at 5 years after the start of SPT was three times higher in the older group than in the adult group, suggesting that age is a risk factor for recurrence. In this study, no risk factors were specific to the older group other than age. This suggests that aggressive open flap debridement can be considered even in patients aged ≥65 years if there are no underlying diseases or compliance problems. However, the possibility of future hospital visits affected by health status and social background, presence of bleeding during probing, increase in pocket depth of ≥6 mm, and changes in the total periodontal inflamed surface area (total PISA), should be fully considered, and regular maintenance should be continued after surgical procedures.