OBJECTIVES: This clinical study aimed to evaluate the accuracy of digital and conventional implant impressions in a fully edentulous maxilla and mandible. METHODS: A 53-year-old edentulous patient with four maxillary and two mandibular implants was selected. Ten intraoral scans (IOS) and a conventional impression per jaw were taken. Clinically verified upper and lower plaster models were digitized using both optical (reference data, n = 10 per model) and tactile laboratory scanner (n = 10 per model). Accuracy was evaluated by comparing the precision and linear/angular deviations of the implants with the reference data. Statistical analyses were conducted using Student's t-test and Kruskal-Wallis test (α = 0.05). RESULTS: In the maxilla, the most significant linear deviations exceeding the 100 µm threshold were found with IOS between implants 1-4. In the mandible, all linear deviations remained below 55 µm. Angular deviations between implants after IOS ranged from 0.01° to 0.40° in the mandible and <
0.01° to 1.86° in the maxilla. After tactile scanning, linear deviations did not exceed 100 µm threshold (except in one distance) and angular deviations ranged from 0.04° to 0.54° (mandible) and <
0.01° to 2.50° (maxilla). The optical scanner demonstrated significantly higher precision (p <
0.001) compared to the IOS and tactile scanner. CONCLUSIONS: Given the significant deviations observed, especially in the maxilla, the optical scanner following conventional impressions remained the preferred method for fully edentulous cases due to its superior accuracy. CLINICAL SIGNIFICANCE: IOS could be a viable alternative particularly for shorter distances in the edentulous jaw, although the clinical implications of these deviations need to be investigated in future studies.