Accuracy (trueness and precision) of a dual-structured light facial scanner and interexaminer reliability
The Journal of Prosthetic Dentistry
Available online 7 January 2020
Abstract
Statement of problem
Digital
waxing procedures should be guided by facial references to improve the
esthetic outcome of a restoration. The development of facial scanners
has allowed the digitalization of the extraoral soft tissues of the
patient’s face. However, the reliability of facial digitizers is
questionable.
Purpose
The
purpose of this study was to evaluate the accuracy (trueness and
precision) of extraoral 3D facial reconstructions performed by using a
dual-structured light facial scanner and to measure the interexaminer
variability.
Material and methods
Ten
participants were included. Six soft-tissue landmarks were determined
on each participant, specifically reference (Ref), glabella (Gb),
subnasal (Sn), menton (Me), chelion right (ChR), and chelion left (ChL).
Interlandmark distances Ref-Sn, Sn-Gb, Ref-Gb, Sn-Me, and ChR-ChL
(intercommissural) were measured by 2 different operators by using 2
different methods: directly on the participant’ face (manual group) and
digitally (digital group) on the 3D facial reconstruction of the
participant (n=20). For the manual group, interlandmark
measurements were made by using digital calipers. For the digital group,
10 three-dimensional facial reconstructions were acquired for each
participant by using a dual-structured light facial scanner (Face Camera
Pro Bellus; Bellus3D). Interlandmark measurements were made by using an
open-source software program (Meshlab; Meshlab). Both operators were
used to note 10 measurements for each manual and digital interlandmark
distance per participant. The intraclass correlation coefficient between
the 2 operators was calculated. The Shapiro-Wilk test revealed that the
data were not normally distributed. The data were analyzed by using the
Mann-Whitney U test.
Results
Significant
differences were found between manual and digital interlandmark
measurements in all participants. The mean value of the manual and
digital group discrepancy was 0.91 ±0.32 mm. The dual-structured light
facial scanner tested obtained a trueness mean value of 0.91 mm and a
precision mean value of 0.32 mm. Trueness values were always higher than
precision mean values, indicating that precision was relatively high.
The intraclass correlation coefficient between the 2 operators was 0.99.
Conclusions
The
facial digitizing procedure evaluated produced clinically acceptable
outcomes for virtual treatment planning. The interexaminer reliability
between the 2 operators was rated as excellent, suggesting that the type
of facial landmark used in this study provides reproducible results
among different examiners.
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