Trueness and passivity of digital and conventional implant impressions in edentulous jaws: a prospective clinical study

Aim: To compare the linear and angular deviations of conventional implant (CI) and digital implant (DI) impression techniques in edentulous jaws with four or six implants. Materials and Methods: Twenty participants (12 men, 8 women; mean age 58.6 years) with complete edentulous maxillary (n = 8) or mandibular (n = 12) arches were included. Each patient received four or six dental implants (Straumann BLX). Both CI and DI were performed using randomized sequences. Linear and angular deviations were measured between the reference scan (coordinated measuring machine) and the CI (desktop scanner) and DI (intraoral scanner, IOS) using CATIA software (Dassault Systèmes). Framework passivity was evaluated using the Sheffield one-screw test. The Shapiro–Wilk test determined data normality (p < 0.05), and nonparametric statistical tests were applied using statistical software. Results: Descriptive statistics showed a mean linear discrepancy of 29.05 (84.80 μm) for CI and 6.95 (154.10 μm) for DI, with angular deviations of 0.06° (0.36°) for CI and 0.05° (1.40°) for DI. No statistically significant differences were found in linear (p = 0.38) or angular (p = 0.12) measurements between CI and DI. Framework passivity testing showed that both techniques achieved passive fit in 17 out of 20 cases (85%), with the reference scan achieving passivity in 18 (90%) cases. Distal implants, particularly in the upper jaw, exhibited greater discrepancies, but none were statistically significant. Conclusions: No significant differences in trueness were found between CI and DI techniques. Both methods demonstrated comparable trueness and framework passivity, supporting the use of IOS as a reliable alternative to CI in edentulous jaws with multiple implants.