Effect of three-segment scanning on the accuracy of intraoral scans in full-arch implant-supported rehabilitation: an in vitro study

PURPOSE: To evaluate the effect of three-segment scanning on the accuracy of digital impressions of full-arch implants obtained using intraoral scanners. METHODS: An edentulous master model with six implants was digitized using a laboratory scanner to create a reference scan. Three intraoral scanners (Primescan, Aoralscan 3 and Trios 5) and two scan strategies were evaluated (n = 10): full-scan (simultaneous full-arch scan) and segmented-scan (the arch categorized into three segments, scanned independently, and subsequently composed into a full-arch dataset) groups. The reference data were scanned using a laboratory scanner. Surface deviation was evaluated with a tolerance of ± 50 μm. The percentage of the total scan body surface area within this tolerance range was calculated as surface trueness. The overall distance deviation between scan bodies was measured to determine linear trueness and precision. RESULTS: For Aoralscan 3 and Trios 5, the segmented-scan group showed higher surface trueness than the full-arch scan group, whereas Primescan showed no statistically significant difference between the scan strategies. The overall distance deviation showed no significant differences in trueness between the full-arch and segmented scans for Primescan, Aoralscan 3, or Trios 5 (all p > 0.05). However, precision was significantly higher under the segmented-scan condition than with full-arch scanning for all evaluated intraoral scanners (all p < 0.01). CONCLUSIONS: For full-arch implant impressions using intraoral scanners, segmented scanning with subsequent composition into a full-arch digital model improved intraoral scanning accuracy compared with simultaneous full-arch scanning.