Automated Tooth Segmentation Faltered Around Recession in Scanner Comparison

Edited by Orthotown staff

Automated tooth segmentation in CAD software was reliable where gingiva was healthy but broke down at sites with pronounced recession, according to an in vitro study of digital and conventional impression systems published Aug. 7 in Clinical Oral Investigations.

Segmentation errors clustered in teeth with pronounced gingival recession, and accuracy improved where the gingiva was healthy. Comparing raw scan data against segmented digital casts produced significant differences for two systems, the Trios 5 at P = .027 and the Dexis IS 3800 W at P = .044.

The authors linked segmentation quality to the underlying scan. Accuracy varied among systems and tracked with raw scan quality, they wrote, noting that precise interdental capture supports planning of tooth movement and reduces manual correction in CAD-based workflows.

On capture accuracy, all five intraoral scanners tested outperformed a conventional polyvinylsiloxane impression in reproducing the interdental areas of a standardized periodontally compromised model, at P less than .001.

Performance among the scanners diverged sharply. Primescan 2 achieved correct interdental reproduction above 80%, while the Dexis IS 3800 W and Trios 5 fell short of that by as much as 20 percentage points. The systems tested were four wireless scanners, the Dexis IS 3800 W, Medit i700w, Primescan 2, and Trios 5, plus the wired Primescan AC.

Scan repair marginally improved interdental capture for some scanners. The conventional impression showed no change after repair.

Katharina Klaus, Linus Vincent Hardt, Bernd Wöstmann, Sabine Ruf, and Maximiliane Amelie Schlenz conducted the study.

The design was laboratory-based and used a single standardized model rather than patients. It measured reproduction accuracy and software behavior, not treatment outcomes, so it does not establish that any system yields better appliance fit or movement results clinically.

Sources:
Clinical Oral Investigations, “Capturing of interdental areas with digital and conventional impression systems and their impact on automatic tooth segmentation in CAD software: an in vitro study,” published online Aug. 7, 2026: link.springer.com/10.1007/s00784-026-07069-2
DOI: doi.org/10.1007/s00784-026-07069-2