Currently submitted to: Journal of Medical Internet Research
Date Submitted: Nov 27, 2019
Open Peer Review Period: Nov 27, 2019 - Jan 22, 2020
(currently open for review)
The influence of scanner precision and analysis software on quantifying 3D intraoral changes: Two-factor factorial experimental design
Digital scanners are being increasingly used to quantify biological topographical changes and clinical health outcomes in primary care settings. However, measurements obtained using these rapidly developing systems are rarely compared with previous precision measurements in tertiary laboratory-based settings.
This investigation used dental intraoral scans to compare a primary care method of measurement (intraoral scanners with an open-source measurement software) with a precision hospital-based method of measurement (laser profilometer and engineering software).
Longitudinal dental wear data from 30 patients were analysed using a two-factor factorial experimental design. At the same appointment, bimaxillary intraoral digital scans (TrueDefinition, 3M, UK) and silicone impressions, poured in type 4 dental stone, were made at baseline and follow up appointments (36 months±10.9). Stone models were scanned using precision laser profilometry (Taicaan, Southampton UK). 3D changes in the digital scans of the first molars (n=76) were quantitatively analysed in both engineering software Geomagic Control (3DSystems, Germany) and free ware WearCompare (Leeds, UK). Volume change(mm3) was the primary measurement outcome in addition to, maximum point loss (microns) and the average profile loss (microns) were recorded. Data, analysed in SPSSv25 (IBM, USA), were paired and skewed. Wilcoxon signed rank tests with Bonferroni correction were used.
The median volume change(IQR) for Geomagic using profilometry was -0.37mm3(IQR-3.75,2.30) and for the intraoral scan +0.51mm3(IQR -2.17,4.26), p<0.001. In WearCompare, the median volume change for profilometry was -1.21mm3(IQR -3.48,0.56) and -0.39 mm3(IQR -3.96,2.76) for intraoral scanning (p=0.039). WearCompare detected significantly greater volume loss than Geomagic regardless of scanner type. No differences were observed between groups when maximum point loss or average profile loss was analysed.
The method of data capture, software used, and measurement metric significantly affected the measurement outcome. The combination of analysing profilometry data in WearCompare reported statistically more volume loss over the study period.
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