Evaluation of the accuracy of extraoral laboratory scanners with a single-tooth abutment model: A 3D analysis.

PURPOSE: The aim of this study was to compare the accuracy of different laboratory scanners using a calibrated coordinate measuring machine as reference.

METHODS: A sand blasted titanium reference model (RM) was scanned with an industrial 3D scanner in order to obtain a reference digital model (dRM) that was saved in the standard tessellation format (.stl). RM was scanned ten times with each one of the tested scanners (GC Europe Aadva, Zfx Evolution, 3Shape D640, 3Shape D700, NobilMetal Sinergia, EGS DScan3, Open Technologies Concept Scan Top) and all the scans were exported in .stl format for the comparison. All files were imported in a dedicated software (Geomagic Qualify 2013). Accuracy was evaluated calculating trueness and precision.

RESULTS: Trueness values (μm [95% confidence interval]) were: Aadva 7,7 [6,8-8,5]; Zfx Evolution 9,2 [8,6-9,8]; D640 18,1 [12,2-24,0]; D700 12,8 [12,4-13,3]; Sinergia 31,1 [26,3-35,9]; DScan3 15,6 [11,5-19,7]; Concept Scan Top 28,6 [25,6-31,6]. Differences between scanners were statistically significant (p<.0005). Precision values (μm [95% CI]) were: Aadva 4,0 [3,8-4,2]; Zfx Evolution 5,1 [4,4-5,9]; D640 12,7 [12,4-13,1]; D700 11,0 [10,7-11,3]; Sinergia 16,3 [15,0-17,5]; DScan3 9,5 [8,3-10,6]; Concept Scan Top 19,5 [19,1-19,8]. Differences between scanners were statistically significant (p<.0005).

CONCLUSIONS: The use a standardized scanning procedure fabricating a titanium reference model is useful to compare trueness and precision of different laboratory scanners; two laboratory scanners (Aadva, Zfx Evolution) were significantly better that other tested scanners.