Abstract
Backgrounds
Intraoral
scanner (IOS) accuracy is commonly evaluated using full-arch surface
comparison, which fails to take into consideration the starting position
of the scanning (scan origin). Previously a novel method was developed,
which takes into account the scan origin and calculates the deviation
of predefined identical points between references and test models. This
method may reveal the error caused by stitching individual images during
intraoral scan. This study aimed to validate the novel method by
comparing the trueness of seven IOSs (Element 1, Element 2, Emerald,
Omnicam, Planscan, Trios 3, CS 3600) to a physical impression digitized
by laboratory scanner which lacks linear stitching problems.
Methods
Digital
test models of a dentate human cadaver maxilla were made by IOSs and by
laboratory scanner after polyvinylsiloxane impression. All scans
started on the occlusal surface of the tooth #15 (universal notation,
scan origin) and finished at tooth #2. The reference model and test
models were superimposed at the scan origin in GOM Inspect software.
Deviations were measured between identical points on three different
axes, and the complex 3D deviation was calculated. The effect of
scanners, tooth, and axis was statistically analyzed by the generalized
linear mixed model.
Results
The
deviation gradually increased as the distance from scan origin
increased for the IOSs but not for the physical impression. The highest
deviation occurred mostly at the apico-coronal axis for the IOSs. The
mean deviation of the physical impression (53 ± 2 μm) was not
significantly different from the Trios 3 (156 ± 8 μm) and CS 3600
(365 ± 29 μm), but it was significantly lower than the values of Element
1 (531 ± 26 μm), Element 2 (246 ± 11 μm), Emerald (317 ± 13 μm),
Omnicam (174 ± 11 μm), Planscan (903 ± 49 μm).
Conclusions
The
physical impression was superior compared to the IOSs on dentate
full-arch of human cadaver. The novel method could reveal the stitching
error of IOSs, which may partly be caused by the difficulties in depth
measurement.
Comments