Time between recall visits and residual probing depths predict long-term stability in patients enrolled in supportive periodontal therapy.

AIM: To relate the time between recall visits and residual periodontal probing depths (PPDs) to periodontal stability in patients enrolled in supportive periodontal therapy (SPT). MATERIALS AND METHODS: Retrospective data on residual PPDs from 11,842 SPT visits were evaluated in SPT patients at the Medi School of Dental Hygiene (MSDH), Bern, Switzerland, 1985-2011. A residual PPD-based algorithm was developed to compute SPT intervals with no expected change of residual PPD. RESULTS: A total of 883 patients aged 43.9 (+/-13.0) years and 55.4% (n = 489) being females were identified. Linear mixed model analysis yielded highest statistically significant impact on PPD change with time between SPT visits, presence of residual PPD >/=4 mm, and bleeding on probing (p < 0.0001). Patients returning for SPT five times consecutively earlier than computed presented mean % PPDs >/=4 mm of 5.8% (+/-3.9) compared with patients returning later (19.2%, +/-7.6) (p < 0.0001). Additionally, patients attending >50% of their SPT visits earlier versus later demonstrated increased periodontal stability after 5 years (p = 0.0002) and a reduced frequency of tooth loss (0.60, +/-0.93 versus 1.45, +/-2.07) after 20 years (p < 0.0001). CONCLUSIONS: To reach and maintain periodontal stability during SPT, individual quantitative data from comprehensive residual PPD profiles may contribute to the improved planning of SPT intervals.