Influence of residual pockets on progression of periodontitis and tooth loss: results after 11 years of maintenance

Background: Limited evidence exists on the significance of residual probing pocket depth (PPD) as a predictive parameter for periodontal disease progression and tooth loss.
Aim: The aim of this study was to investigate the influence of residual PPD 5 mm and bleeding on probing (BOP) after active periodontal therapy (APT) on the progression of periodontitis and tooth loss.
Material and Methods: In this retrospective cohort, 172 patients were examined after APT and supportive periodontal therapy (SPT) for 3–27 years (mean 11.3 years). Analyses were conducted using information at site, tooth and patient levels. The association of risk factors with tooth loss and progression of periodontitis was investigated using multilevel logistic regression analysis.
Results: The number of residual PPD increased during SPT. Compared with PPD3 mm, PPD=5 mm represented a risk factor for tooth loss with odds ratios of 5.8 and 7.7, respectively, at site and tooth levels. The corresponding odds ratios for PPD=6 mm were 9.3 and 11.0 and for PPD7 mm 37.9 and 64.2, respectively. At patient level, heavy smoking, initial diagnosis, duration of SPT and PPD6 mm were risk factors for disease progression, while PPD6 mm and BOP30% represented a risk for tooth loss.
Conclusion: Residual PPD6 mm represent an incomplete periodontal treatment outcome and require further therapy.