Long-term tooth retention in chronic periodontitis - results after 18 years of a conservative periodontal treatment regimen in a university setting.

Aim: The longitudinal study assessed the risk of tooth loss under a non-regenerative treatment regimen and aimed to identify prognostic factors for tooth loss.

Methods: Three hundred and fifteen patients (8009 teeth) were examined before (T0) and after active periodontal therapy (APT, T1) as well as after (mean ± SD) 18 ± 6 years of supportive periodontal therapy (SPT, T2). Descriptive statistics and a Cox proportional hazards shared-frailty model were applied.

Results: Overall, 351 and 816 teeth were lost during APT and SPT, respectively, with 0.15 ± 0.17 teeth being lost per patient and year. Seventy-two percentage patients lost 0-3, 24% 4-9 and 4% ≥10 teeth. The proportion of teeth with probing-pocket depths (PPD) >6 mm was 17.2% (T0), 1.6% (T1) and remained stable at 1.7% up to T2. Tooth loss during SPT was significantly increased in older patients [HR (95% CI): 1.04 (1.01-1.07) per year] and smokers [2.62 (1.34-5.14)], with each mm of PPD [1.35 (1.17-1.56)], in multirooted compared with single-rooted teeth [1.86 (1.36-2.56)] and teeth with bone loss [BL; HR up to 23.6 (12.1-45.6) for BL > 70%].

Conclusion: The risk of tooth loss was generally low under the provided non-regenerative treatment regimen; a minority of patients were responsible for the majority of teeth lost during SPT.