Optimizing Digital Impressions in Edentulous Patients Through Reference Point-Enhanced Scanning: A Quantitative Assessment of Accuracy and Time Efficiency

Background: Digital impression techniques for edentulous patients present unique challenges due to the absence of stable anatomical landmarks and variable soft tissue morphology. While intraoral scanners have shown promising results in dentate patients, their application in edentulous cases remains problematic, with reported accuracy deviations ranging from 60.6 ± 11.9 μm to 67.2 ± 6.9 μm compared to conventional methods. Material and Methods: This pilot study employed a within-subject, repeated-measures design comparing four scanning protocols in a fully edentulous patient (age: 42, BMI: 24.3 kg/m2, Cawood and Howell Class III). Digital scans were performed using iTero Element 5D and Trios 5 scanners (n = 10 scans per group), with and without a modified technique incorporating standardized reference points (1 mm diameter, 5 mm intervals) and systematic soft tissue management. A conventional impression-derived digital model served as the reference standard. Accuracy assessment utilized best-fit alignment and root mean square (RMS) calculations through Geomagic Control X software (version 2020.1.1). Results: The modified technique demonstrated significantly improved accuracy (Groups C/D: 57.8–59.7 μm) compared to standard protocols (Groups A/B: 66.9–68.2 μm) (p < 0.001). Mean scanning times were reduced by 37% with the modified technique (2:10 ± 0:09 min vs. 3:24 ± 0:15 min). Inter-operator reliability showed excellent agreement (ICC = 0.92, 95% CI: 0.88–0.95). Soft tissue management significantly improved vestibular area accuracy (48.7 ± 6.3 μm vs. 72.4 ± 8.9 μm, p < 0.001). Conclusions: The proposed scanning strategy incorporating reference points and systematic soft tissue management significantly improved both accuracy and efficiency in digital impressions of edentulous arches. The technique showed excellent reproducibility and potential clinical applicability across different scanner systems. These findings warrant validation through larger-scale clinical trials to establish definitive protocols for digital impression-taking in edentulous patients.