The effect of intraoral scanner tip size and scanning strategy on the digital impression trueness of full-arch implant-supported prostheses: an in vitro study

Purpose

The purpose of this in vitro study was to evaluate the effect of scanner head size, scanning path, and scanning strategy on the trueness of complete-arch digital implant impressions in an edentulous maxilla.

Materials And Methods

An edentulous maxillary model with four implants was digitized using a laboratory scanner to generate a reference dataset. Digital impressions were obtained using two scanner head sizes, two scanning paths, and three scanning strategies, resulting in twelve experimental groups, with ten scans for each group under standardized conditions. Root mean square and angular deviations between the reference dataset and each test scan were calculated using a best-fit algorithm. Statistical analysis was performed with the level of significance set at α = .05.

Results

The highest median deviation was observed in the medium scanner head with the single scanning strategy group (M.I.S., 51.5 µm), whereas the lowest deviation was found in the large scanner head with the double scanning strategy group (L.P.D., 17.5 µm). All large-head scans showed significantly lower RMS and angular deviation values than the medium-head scans (P < .001). Among medium-head groups, the reverse double scan produced the lowest RMS values (M.I.R., 40.5 µm; M.P.R., 38 µm), while the single-scan groups showed the highest deviations (M.I.S., 51.5 µm; M.P.S., 49.5 µm). Scanning path showed no significant effect on trueness.

Conclusion

Scanner head size and scanning strategy significantly affected trueness. Clinically, larger scanner heads combined with appropriate scanning strategies may improve trueness in full-arch or extended edentulous scans by reducing cumulative stitching errors.