Variables affecting tooth survival and changes in probing depth: A long-term follow-up of periodontitis patients

Aim To retrospectively assess tooth-survival rate and its association with patient and oral variables in periodontal office patients, followed up to 18 years. Material and Methods Patients in a private periodontal office whose files included initial examination (T₀), reevaluation (T_Re) and ≥10 years after T₀ (T_F) chartings, and received periodontal therapy and supportive periodontal therapy (SPT) after T_Re were included. General health, plaque scores (PI), probing depth (PPD), bleeding on probing (BOP) at six points/tooth, tooth extractions, and SPT visits were extracted from patient files at T₀, T_Re, and T_F. Descriptive statistics and Cox regression analysis were performed. Results Fifty patients (mean 26 ± 4 teeth/patient, 1301 teeth) fulfilled inclusion criteria. About 20 and 129 teeth respectively were extracted before/after T_Re, 96 of them for periodontal causes. PPD>7 mm at T_Re (HR = 17.7, 95%CI 8.6, 36.6), age above 60 years (HR = 3.3, 95%CI 1.5, 7.2), multi-rooted teeth (HR = 1.9, 95%CI 1.2, 3.1) and SPT<3 times/year (HR = 1.8, 95%CI 1.1, 2.9), were the best prognostic factors for tooth loss during follow-up. (p < 0.05, Cox regression analysis). A continuous, statistically significant reduction was observed in mean PPD among teeth that survived follow-up [4.3 ± 1.8 mm, 3.5 ± 1.4 mm, 3.2 ± 1.3 mm, at T₀, T_Re, T_F, respectively. (p < 0.001, Repeated-measures test)]. Conclusion Regular SPT was associated with low tooth-loss rates and continuous reductions in probing depth. PPD after initial therapy, age above 60, multi-rooted teeth and infrequent SPT were strong negative prognostic factors for long-term tooth survival among periodontal patients.