Correlation between periodontal parameters at teeth and implants: An up to 20-year long-term observational cohort study in periodontitis patients

OBJECTIVES: The study aimed to evaluate the long-term correlation between periodontal parameters at implants and contra-lateral natural teeth over a follow-up period of up to 20 years in periodontitis patients undergoing supportive periodontal care (SPC). MATERIALS AND METHODS: This observational cohort study involved systemically healthy, non-smoking patients who received periodontal and implant therapy, followed by regular SPC. The following parameters were assessed at baseline (i.e. implant loading) and at 5, 10, 15 and 20 years: clinical attachment level (CAL), pocket probing depth (PPD), gingival margin (GM) and bleeding on probing (BOP). Intra- and inter-group differences over time between implants and teeth were analysed. Survival rates were calculated. RESULTS: 167 patients with 419 implants were included. Mean CAL increased significantly over time at implants and teeth (p≤0.015), approximately doubling every five years. After 20 years, CAL loss amounted to 4.47±2.45mm at implants and 4.38±2.64mm at teeth. Implants demonstrated significantly greater PPD increases after 10 and 15 years compared with teeth (p≤0.027), whereas differences in CAL between implants and teeth were largely non-significant beyond 5 years. Differences in GM and BOP were small and inconsistent. No association was observed between SPC frequency and changes in CAL or PPD. Implant survival was 100% and three contra-lateral teeth were lost over 20 years. CONCLUSIONS: In patients with treated periodontitis under regular SPC, implants and natural teeth exhibited comparable long-term clinical stability and survival. However, a non-linear progression of CAL loss occurs at teeth and implants, which SPC effectively limits but does not completely prevent.