operator differences: for instance, both White et al. [19]
and El-Zanaty et al. [20] assessed only intra-examiner
bias. Indeed, two or three different operators were
involved in other studies, but only intra-operator
variability was reported [6]. Similarly, Wiranto et al. [8]
assessed the variability from three different operators,
but did not report the actual inter-operator data,
quoting a previous investigation.
The excellent reproducibility of the three different
measurement techniques is in line with the current
literature reports. For instance, De Luca Canto et al.
[2] made an extensive review to study the validity of
measurements obtained from digital dental models
produced from laser scanning against those directly
made on the original physical dental models. The
authors concluded that the current scientific evidence
supports the validity of digital measurements.
White et al. [19] tested the accuracy of the digital
reproductions of dental models made by using CBCT
scans, and foun d satisfactory values for intra-arch
measurements but inaccurate inter-arch relationships.
El-Zanaty et al. [20] compared linear distances obtained
on plaster casts and from CT head scans; the two
techniques had excellent agreement. More recent
studies reported that both intraoral scanning and
CBCT scanning of alginate impressions of the dental
arches gave valid, reliable, and reproducible dental
measurements for diagnostic purposes.
Wiranto et al. [8] compared traditional plaster scans,
scans obtained from intraoral scans, and CBCT scans
of alginate impressions, and found that the digital
reproduction of dental arches can be usefully employed
for diagnostic purposes.
In the current study, the worst coefficients of
reproducibility were found for CBCT measurements, while
the best were those obtained for plaster casts. For CBCT,
similar data were reported by Kim et al. [4, 5]. Literature
is not in agreement about the technique with the best
reproducibility: both digital models [4, 5, 7], and plaster
models [16] had the best scores in different studies.
Overall, only three mesiodistal crown diameters had
differences larger than 0.5 mm, which is considered the
threshold for clinical acceptability [7, 18]. This corresponds
to 8% of the analysed dental distances (3 out of 12
distances x 3 techniques values), a value larger than that
reported by Tarazona-Álvarez et al. [6] who found only
5% of significant differences when comparing 20 linear
distances obtained directly on dried mandibles and on
their CBCT scans. Additionally, the current results well
confirm that measurements involving the premolars are
more variable than the other ones [4].
In general, the overestimation of calliper measurements
vs. digital casts data is in line with the literature reports
[18], while the comparison with CBCT data is more
scattered. For instance, on dry mandibles, most of CBCT
measurements were significantly smaller than those
obtained by using the calliper [6].
5. Conclusion
In conclusion, measurements on digital dental models
and CBCT reconstructions of the dental arches seem
clinically reliable as direct measurements performed on
dental plaster casts. Inter- and intra-operator reliability
Stomatology Edu Journal
Table 3. P values from Kruskal-Wallis test.
Central
First
First
First
First
Canine
incisor
premolar molar premolar molar
Hemiarch
Mesiodistal
Vestibulopalatal
Left
maxillary 0.09 0.93 0.002* 0.93 0.18 0.47
Right
mandibular 0.05 0.55 0.86 0.36 0.93 0.44
*Significant difference p < 0.01. For significant values, post hoc Wilcoxon tests:
Calliper – CBCT: p = 0.002; Digital - CBCT: p = 0.03.
were acceptable, while more care may be needed for
CBCT measurements, as also underlined by previous
studies [3, 4].
The results are promising, nevertheless further
evaluations on a larger sample are advised.
Author Contributions
LP: design of the study, data collection and
interpretation, drafting the MS, final approval of the
MS; MC: design of the study, data elaboration, drafting
the MS, final approval of the MS; SG: data collection,
critical review of the MS, final approval of the MS; FMER:
data collection and elaboration, critical review of the
MS, final approval of the MS; GMT: design of the study,
data elaboration and interpretation, critical review of
the MS, final approval of the MS; VP: design of the study,
data collection, drafting the MS, final approval of the
MS; CS: design of the study, data interpretation, critical
review of the MS, final approval of the MS.
ARE DENTAL MEASUREMENTS TAKEN ON PLASTER CASTS COMPARABLE TO THOSE
TAKEN FROM CBCT IMAGES AND LASER SCANNED SURFACES?
Acknowledgments
Not applicable. The study was self-funded. There are
no conflicts of interest and no financial interests to be
disclosed.
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