OBJECTIVES: This retrospective, non-interventional study aimed to evaluate the longevity and factors influencing the success of custom-fabricated polyetheretherketone (PEEK) post-and-cores in endodontically treated teeth (ETT). MATERIAL AND METHODS: During the observation period (2019-2022), 63 patients received 100 customized PEEK post-and-cores. Clinical outcomes were analyzed based on the following parameters: age, gender, tooth type, tooth position, proximal contacts, remaining cavity walls, antagonist contacts, and final restoration. Kaplan-Meier analysis was used for the survival probability. Log-rank tests were used to identify univariate associations between failure rates and other potential factors. Cox regression was used to assess the risk of failure and determine possible risks between the identified factors at a cut-off point p-value (0.25 in univariate analysis). RESULTS: The median follow-up duration was 20.62 months, with a maximum of 40.57 months. 93 restorations were judged as successful and 99 teeth survived. The main failure type was decementation of the restoration (n = 4). The annual failure rate was 3.4%. Gender, remaining tooth structure, and final restoration were found to be correlated with success rates in the preliminary univariate analysis (Log-rank tests) to determine the association between failure rates and potential factors. Multifactorial survival analysis (Cox regression) showed that teeth with coronal walls had a significantly lower failure risk than deprived teeth, even with the ferrule effect. (HR = 0.04
95% CI for HR = 0.01-0.29
p = 0.002). CONCLUSIONS: PEEK post-and-cores adapt well to clinical restorative needs and offer favorable short-term clinical outcomes. The remaining cavity wall was a significant success rate predictor.