Purpose: To investigate the long-term (up to 20 years) outcomes of customized post copings (PC) and to evaluate potential factors influencing the risk for complications. Materials and Methods: Patients treated with PC-retained overdenture prostheses (OD) in a university setting were selected. Data collected included dental and periodontal parameters, periapical radiographs, and assessment of the OD design. Patientreported satisfaction levels were evaluated using visual analog scales (VAS), and 20-year cumulative survival and success rates were calculated. Results: A total of 73 patients with 81 ODs and 152 PCs were included. PC survival rate was 80.9%, and the success rate amounted to 64.5% after a mean observation period of 105.4 (± 67.9; range: 6 to 240) months. The 20-year cumulative PC rates were 91.5% for survival and 79.3% for success. Activation of matrices was more frequent with ball attachments than with cylindrical retention (odds ratio [OR] 0.43; 95% confidence interval [CI] 0.2 to 0.94; P = .034). Cylindrical retention was rated significantly better at 96% (interquartile range [IQR] 89.5% to 100%) compared to ball attachment at 88% (IQR 79% to 98.2%; P = .012). The risk for PC complications was higher for OD designs with coverage of the periodontal tissues compared to open designs (OR 0.34; 95% CI 0.15 to 0.78; P = .010). Conclusion: Customized PCs on natural abutment teeth for the retention of ODs are a valid treatment in partially dentate patients. Correct prosthesis design and integration into a regular dental hygiene program are mandatory factors for long-term success.