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1. Comparison of dental measurements
between conventional plaster models,
digital models obtained by impression
scanning and plaster model scanning
Nisa Gül Amuk 1
, Erol Karsli 2
, Gokmen Kurt 3
1. Erciyes University, Faculty of Dentistry, Department of Orthodontics, Kayseri,
Turkey
2. Private Practice, Adana, Turkey
3. Bezmialem Vakif University, Faculty of Dentistry, Department of Orthodontics,
Istanbul, Turkey
Correspondence:
Nisa Gül Amuk, Erciyes University, Faculty of Dentistry, Department of Orthodontics,
38039 Melikgazi, Kayseri, Turkey.
nisa.gul86@hotmail.com
Keywords
Orthodontics
Model analysis
Plaster dental model
Digital dental models
Plaster model scanning
Dental impression
scanning
Summary
Objective > Comparison of dental measurements between conventional plaster models, digital
models obtained by impression scanning and plaster model scanning.
Purpose > To evaluate and to compare the accuracy and reliability of tooth size, arch width and
Bolton tooth size discrepancy measurements on 3 Dimensional (3D) digital models obtained by
plaster dental model scanning, dental impression scanning and conventional plaster models.
Material and methods > This study was carried out on the maxillary and mandibular dental models
of 25 patients with Angle Class I molar relationship and minimal crowding. Mesio-distal dimen-
sions of the teeth, intercanine and intermolar arch width, and Bolton tooth size discrepancy
measurements were calculated by conventional methods on plaster models, digital methods and
on 3D models obtained from plaster model scanning and impression scanning. All measurements
were repeated after three weeks for each of the investigated methods. Reliability of measure-
ments was evaluated by Dahlberg formula and Pearson Correlation Coefficient. Comparisons of
dental measurements between three methods were achieved with ANOVA Test.
Results > The repeated measurements were highly correlated for all methods. Method error was
found within clinically acceptable limits. There was no significant difference between dental
measurements on plaster dental models, digital models obtained from plaster dental model
scanning and dental impression scanning. Results showed the methods being highly reliable and
accurate for tooth size, arch width and Bolton analysis at total and anterior proportion calculation.
Conclusion > Digital measurements of tooth size, arch width and Bolton tooth size discrepancy on
digital models obtained from plaster dental model scanning and dental impression scanning
showed high accuracy and reliability. There was no significant difference between the three
methods for dental measurements.
Available online: 13 February 2019
tome 17 > n81 > March 2019
https://doi.org/10.1016/j.ortho.2019.01.014
© 2019 CEO. Published by Elsevier Masson SAS. All rights reserved.
151
Original
article
International Orthodontics 2019; 17: 151–158
Websites:
www.em-consulte.com
www.sciencedirect.com

2. Introduction
Successful and satisfactory treatment outcomes can be obtained
with subsequent and comprehensive diagnosis and treatment
planning. The analysis of dental models is a valuable tool in
orthodontic diagnosis and treatment planning which allows
examination of the occlusion and dentition from all three
dimensions to analyse the degree and the severity of dental
malpositions and/or malocclusions for diagnosis and treatment
planning. For achieving ideal dental alignment and ideal occlu-
sion, orthodontic model analyses including determination of
spaces, crowding, rotations, tooth sizes, tooth size discrepan-
cies, arch form, arch symmetry, arch dimensions, tooth-arch
discrepancies and other dental information have great
importance.
Conventional model analyses have been performed on plaster
dental models, which can be lost, fractured or ruptured and have
degradation. Although dental measurements on plaster models
or photographs by calipers are time-consuming [1] and prone to
error because of anatomical variations, individual factors or
malposition and inclination of teeth [2], they have also been
the most commonly used form of model analyses from past to
present through the simple nature of the method. Recently,
many advances in computer sciences have replaced traditional
methods in orthodontic practice, because they provide qualified
diagnostic tools at a reasonable cost [3]. The potential
advantages of digital models depend on the ability to analyse
tooth and/or arch characteristics in a three-dimensional aspect
by which measurement error reasons during traditional meth-
ods might be eliminated [4].
Digital models have become widespread in dental offices and
there are different options for obtaining 3 Dimensional (3D)
dental models. Surface scanning technology was first used for
construction of 3D study models via surface scanning of plaster
models in 1999 by OrthoCad [4]. This technology was used to
generate digital study models using different ways such as
alginate impression scanning or direct intraoral scanning which
may be more economic and beneficial by both saving time and
pouring material compared to plaster model scanners [5].
Digital models offer more advantages such as instant accessi-
bility of 3D information without the need for the retrieval of
plaster models from a storage area, reduced need of large areas
for plaster model storing, less time-consuming analysis, ability
to share information via the internet with other professionals
and objective rather than subjective model grading analysis for
American Board of Orthodontics (ABO) certification [4,6]. With
3D digital models, clinicians can evaluate dental models in
three-dimensional aspects and perform dental analysis in more
detail. Relationships between maxillary and mandibular arches
can be better viewed in occlusion on different perspectives in 3D
images and their software [7]. Digital models also provide
Mots clés
Orthodontie
Analyse de modèles
Moulage en plâtre
Modèles numérisés
Numérisation de modèles
en plâtre
Impression 3D empreinte
optique
Résumé
Comparaison des mesures dentaires sur différents modèles : en plâtre classique,
imprimés à partir d'empreintes optiques, numérisés à partir des modèles en plâtre
But > E´valuer et comparer la précision et la fiabilité des mesures de la taille des dents, de la
largeur de l'arcade et de la dysharmonie dento-dentaire de Bolton (DDD) sur trois types de
modèles : en plâtre classique, numérisés en 3D à partir des modèles en plâtre, imprimés en 3D à
partir d'empreintes optiques.
Matériel et méthodes > Cette étude a été menée sur des modèles dentaires maxillaires et
mandibulaires de 25 patients présentant une relation molaire de classe I d'Angle et un encombre-
ment minimal. Les dimensions mésiodistales des dents, les largeurs de l'arcade intercanine et
intermolaire ainsi que les mesures de la DDD ont été calculées grâce à des méthodes classiques
sur des modèles en plâtre, des méthodes numériques avec Images 3D obtenues par numérisation
de modèles de plâtre et avec impression 3D à partir d'empreintes optiques. Toutes les mesures
ont été répétées après trois semaines pour chacune des méthodes étudiées. La fiabilité des
mesures a été évaluée par la formule de Dahlberg et le coefficient de corrélation de Pearson. Des
comparaisons de mesures dentaires entre les trois méthodes ont été réalisées avec l'analyse de
variance à mesures répétées Anova.
Résultats > Les mesures répétées ont été fortement corrélées pour toutes les méthodes. L'erreur
de méthode était dans les limites cliniquement acceptables. Aucune différence significative
existait entre les mesures dentaires sur les modèles en plâtre, numérisés à partir des modèles en
plâtre et imprimés en 3D à partir des empreintes optiques. Les résultats ont montré que les
méthodes étaient très fiables et précises pour la taille des dents, la largeur de l'arcade et l'analyse
de Bolton lors du calcul du rapport global et du rapport antérieur.
N. Gül Amuk, E. Karsli, G. Kurt
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3. virtual treatment and virtual setup [8]. 3D models can be
processed to analyse specific teeth and to estimate the axis
or position of individual teeth, which provides three-dimen-
sional prediction of tooth movement by superimposing dental
changes on stable reference structures [4]. However all of these
advantages may be accepted as valid, if their accuracy and
reliability are proved clinically.
Sousa et al. [7] evaluated the reliability of measurements made on
3D digital models obtained with a plaster model scanner and
concluded that no statistically significant differences were found
between the measurements made directly on the plaster dental
models and on the digital models obtained by plaster dental
model scanning. The authors suggested that linear dental meas-
urements on digital models were accurate and reproducible.
Camardella et al. [9] tested the accuracy and reliability of measure-
ments on digital models obtained by scanning impressions made
from soft putty polyvinylsiloxane materials and they concluded
that digital models acquired by impression scanning may be used
with clinically acceptable accuracy, reliability, and reproducibility.
El-Zanaty et al. [10] also found strong correlation between dental
measurements on digital models and plaster models. Similarly,
Leifert et al. [11] investigated the accuracy of measurements on
digital models by OrthoCad software and reported that digital
models were clinically acceptable and reproducible when com-
pared with traditional model analyses, even though slight differ-
ences were found on mesio-distal tooth widths and arch length
measurements. On the other hand, Tomassetti et al. [12] reported
reasonable but clinically acceptable correlation between conven-
tional measurements using Vernier calipers and OrthoCad com-
puterized digital measurement for Bolton tooth size analysis.
Redlich et al. [13] performed dental measurements on 3D ortho-
dontic models with Teledent software and suggested that the
accuracy of linear dental measurements was sometimes question-
able especially in severely crowded dentitions.
According to these findings, literature presents conflicting data
regarding the accuracy of dental measurement on digital mo-
dels obtained from the scanning of plaster models and offers
limited data regarding digital models acquired by impression
scanning method. In addition, after a review of the literature no
study has compared the reliability and accuracy of model anal-
yses performed on 3D models obtained from plaster dental
model scanning and dental impression scanning methods.
Therefore, the purpose of present study was to evaluate and
to compare the reliability and accuracy of model analyses carried
out using conventional measuring method on plaster models
and digital measurements on 3D digital models obtained by
plaster dental model scanning and dental impression scanning
methods.
Material and methods
A power analysis conducted using the G*Power ver. 3.0.10.
software (Franz Faul, Universität Kiel, Germany) estimated
that a sample size of 18 dental models would give more than
95% power to detect significant differences with an effect size
of 0.80 at an a = 0.05 level of significance. Twenty-five
patients who had healthy teeth without fractures, abrasions
or size-shape abnormalities, had minimal crowding with Class
I molar relationship in permanent dentition and had no uner-
upted or missing teeth were included in this study. Alginate
(Tropicalgin, Zhermack, Italy) impressions were taken from
the upper and lower jaws of patients two times by the same
clinician. Impressions were repeated until no positive or neg-
ative bubbles, deformation of impressions or separation of
impressions from trays were observed (figure 1). First impres-
sions were used to obtain digital models by 3D impression
scanner (DWOS iSeries Dental Impression Scanner, Dental
Wings Inc., Canada) while plaster models were produced by
pouring of the second impressions in plaster and removed
from patients a maximum of 10 minutes after buccal impres-
sion taking in order to avoid distortion or variation on alginate
impressions. When the base of the plaster models was
trimmed and prepared, plaster models were scanned with
3 Shape model scanner (3 Shape R700 3D Scanner, 3 Shape A/
S, Copenhagen, Denmark) and digital models of same patients
were produced by the scanning of dental impression (figure 2)
and scanning of plaster models (figure 3). The examiner was
experienced in using both methods: measuring with a digital
caliper on plaster models and using software for analysis on
digital models (figure 4). Conventional measurements were
performed on upper and lower plaster models using a digital
caliper (SHANTM
132A Series Digital Caliper, SHAN Precision
Measuring Instruments, Allen Designs LLC) with 0.01 mm
Figure 1
Alginate dental impression of maxillary dental arch
Comparison of dental measurements between conventional plaster models, digital models obtained by
impression scanning and plaster model scanning
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4. accuracy. Digital model analyses on digital models were car-
ried out using 3 Shape 3D software (2010, Version 1.0, Soft-
ware 3 Shape A/S, Copenhagen, Denmark) for plaster dental
model scanning images and DWOS software (DWOS
Orthodontic Archiving Software, Dental Wings Inc., Canada)
for impression scanning images.
Model analyses included the following measurements:
tooth size: distance between mesial and distal contact points
of teeth from right first molar to left first molar in upper and
lower arches;
intermolar width: distance between the mesio-buccal cusp
tips of the right and left first molars for both arches;
intercanine width: distance between the tips of right and left
canines at both arches;
Bolton analysis: for 6 teeth and 12 teeth using tooth sizes.
Dental measurements on the plaster models, digital models
obtained with plaster model scanning and digital models
obtained with dental impression scanning were repeated for
12 randomly selected patients after 21 days by the same
examiner.
Statistical analysis
All measurements were recorded in a Microsoft Excel
2000 spreadsheet (Microsoft, Redmond, Wash) and analysed
with SPSS version 20.0 (SPSS, Chicago, Ill). Variables were eval-
uated for normality (Shapiro-Wilk test) and for homogeneity of
variances (Levene test). The method errors were calculated by
using the formula described by Dahlberg. Reliability of measure-
ments for both methods was assessed with Pearson Correlation
Coefficient. The accuracy of model analyses on digital models
obtained with plaster dental model scanning and dental
Figure 2
Digital model reconstruction using DWOS impression scanner
Figure 3
Digital model reconstruction from plaster dental models using
3 Shape model scanner
Figure 4
Digital dental measurements on digital models using software
N. Gül Amuk, E. Karsli, G. Kurt
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5. impression scanning methods were assessed with one-way
analysis of variance (ANOVA) test. The results were considered
significant at P 0.05.
Results
The intraexaminer random errors ranged from 0.01 mm to
0.67 mm for dental measurements (table I) and for Bolton analysis
from 0.34 mm to 0.72 mm at the by means of the different
methods (table II). Whole repeated dental measurements and
Bolton analysis were highly correlated for 3 methods (tables I
and II). The Pearson Correlation Coefficient for dental measurement
values ranged between 0.738 and 0.999 (table I), and for Bolton
analysis from 0.812 to 0.972 (table II).
The results of dental measurement accuracy on digital models
were shown on Table III. Tooth size values of right and left first
molar, premolars, canine, incisor teeth, intermolar and interca-
nine width measurements had no significant difference
between the three methods.
TABLE I
Method error of the dental measurements calculated with Dahlberg's formula and Pearson Correlation Coefficient for all investigated
methods.
Upper arch Lower arch
Plaster model Plaster model scanning Impression Scanning Plaster model Plaster model scanning Impression scanning
Dahlberg (mm) PCC Dahlberg (mm) PCC Dahlberg (mm) PCC Dahlberg (mm) PCC Dahlberg (mm) PCC Dahlberg (mm) PCC
R6 0.130 0.921**
0.198 0.877**
0.182 0.915**
0.227 0.829*
0.234 0.964**
0.145 0.941**
L6 0.199 0.834**
0.162 0.931**
0.111 0.949**
0.158 0.879**
0.120 0.966**
0.228 0.968**
R5 0.224 0.776**
0.110 0.898**
0.120 0.944**
0.056 0.989**
0.107 0.971**
0.270 0.960**
L5 0.127 0.884**
0.110 0.912**
0.122 0.861**
0.054 0.989**
0.079 0.971**
0.183 0.971**
R4 0.220 0.912**
0.070 0.954**
0.096 0.969**
0.057 0.889**
0.098 0.982**
0.121 0.941**
L4 0.209 0.894**
0.056 0.914**
0.098 0.962**
0.073 0.822**
0.050 0.960**
0.137 0.989**
R3 0.024 0.990**
0.092 0.917**
0.120 0.890**
0.107 0.858**
0.083 0.982**
0.099 0.965**
L3 0.102 0.971**
0.068 0.934**
0.097 0.987*
0.094 0.985**
0.118 0.990**
0.277 0.958**
R2 0.166 0.835**
0.136 0.860**
0.193 0.998**
0.095 0.993**
0.154 0.889**
0.070 0.922**
L2 0.093 0.809**
0.109 0.987**
0.121 0.999**
0.073 0.897**
0.072 0.945**
0.100 0.958**
R1 0.221 0.862**
0.097 0.980**
0.114 0.972**
0.016 0.958**
0.144 0.914**
0.087 0.927**
L1 0.108 0.947**
0.207 0.789**
0.103 0.984**
0.114 0.823**
0.077 0.898**
0.148 0.902**
IMW 0.128 0.906**
0.843 0.779**
0.427 0.926**
0.251 0.828**
0.414 0.989**
0.571 0.975**
ICW 0.012 0.971**
0.673 0.977**
0.419 0.977**
0.473 0.738**
0.401 0.998**
0.575 0.941**
PCC: Pearson Correlation Coefficient; R: right; L: left; IMW: Intermolar width; ICW: Intercanine width.
*
Statistically significant difference at P 0.01.
**
Statistically significant difference at P 0.001.
TABLE II
Method error calculation and comparison of the Bolton tooth size discrepancy measurements for investigated methods.
Plaster model Plaster model scanning Impression scanning p
Mean SD Dahlberg PCC Mean SD Dahlberg PCC Mean SD Dahlberg PCC
Bolton 6 1.23 1.73 0.336 0. 903**
1.22 1.73 0.567 0.916**
0.91 2.01 0.523 0.923**
0.302
Bolton 12 1.17 1.81 0.581 0.872**
1.19 2.63 0.724 0.812**
1.02 2.69 0.388 0.972**
0.128
SD: standard deviation; PCC: Pearson Correlation Coefficient.
**
Statistically significant difference at P 0.001.
Comparison of dental measurements between conventional plaster models, digital models obtained by
impression scanning and plaster model scanning
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6. Discussion
Advanced computerized systems and digital dental models offer
promising clinical solutions for orthodontists. In order to men-
tion these clinical advantages, the accuracy and reliability of
these digital systems should be clarified. So, the aim of this
present study was to investigate the accuracy and reliability of
dental measurements on 3D digital models obtained from plas-
ter dental model scanning and dental impression scanning
methods.
Findings of this study showed excellent agreement between
plaster models and digital models obtained from plaster dental
model scanning and dental impression scanning in dental meas-
urements. In addition, all methods were found repeatable and
reliable with minor method errors. The findings of this present
study related to the reliability of dental measurements on digital
models obtained from the model scanner were consistent with
previous studies [1,3,14,15].
Abizadeh et al. [16] reported statistically significant differences
between model analysis on plaster models and on digital mo-
dels obtained from model scanner. As a result, the authors
stated plaster model measurements were more repeatable than
digital models [16]. Many factors should be considered that
could influence the reliability of measurements on digital mod-
els, such as crowding, abnormal inclination and rotation of teeth
for different types of casts or at different times for the same
models [17]. This situation affects the linear dental measure-
ments, tooth-arch discrepancies and Bolton analyses in addition
to repeatability of measurements. Zilberman et al. [15] tested
the accuracy of measurements on plaster models with the aid of
calipers and on the OrthoCAD at various malocclusions and found
the greatest difference on dental measurements at the premo-
lar region because of crowding. In addition, they observed the
greatest systematic error in the molar group because of the
special morphology of upper molars. In order to eliminate these
factors, which can lead to errors on measurements, dental
models having moderate or severe crowding and teeth with
malformation were excluded from our study.
The other factors that may influence the validity or reproducibil-
ity of measurements and consumed time for the selection of
points are the training and experience of the examiner with
digital measurements on software [7,15]. Landmark identifica-
tion may be difficult on 3D images because of the view of
TABLE III
Comparison of tooth size, intermolar and intercanine width measurements between investigated methods.
Upper arch Lower arch
Plaster model Plaster model scanning Impression scanning P Plaster model Plaster model scanning Impression scanning P
Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD
R6 10.3 0.6 10.6 0.6 10.7 0.6 0.12 11.0 0.6 11.3 0.9 11.2 0.8 0.53
L6 10.4 0.5 10.9 0.9 10.7 0.6 0.14 11.5 0.7 11.5 0.8 11.5 0.7 0.15
R5 6.6 0.4 6.9 0.4 6.8 0.5 0.16 7.0 0.4 7.4 0.5 7.4 0.6 0.06
L5 6.7 0.5 6.9 0.4 6.9 0.4 0.40 7.0 0.4 7.1 0.5 7.2 0.5 0.71
R4 6.7 0.4 6.9 0.5 6.8 0.6 0.73 6.9 0.5 7.1 0.4 7.2 0.4 0.28
L4 6.8 0.5 7.1 0.5 7.0 0.4 0.34 6.9 0.5 7.2 0.5 7.1 0.4 0.07
R3 7.7 0.6 7.9 0.7 7.6 0.7 0.30 6.5 0.6 6.9 0.6 6.9 0.5 0.12
L3 7.6 0.7 7.6 0.4 7.6 0.7 0.98 6.8 0.6 6.8 0.6 6.8 0.6 0.49
R2 6.6 0.7 6.9 0.7 7.0 0.8 0.31 5.4 0.4 5.5 0.2 5.5 0.4 0.57
L2 6.7 0.6 6.9 0.8 6.9 0.8 0.56 5.5 0.4 5.6 0.2 5.5 0.3 0.56
R1 8.5 0.8 8.7 0.8 8.5 0.9 0.61 5.1 0.3 5.3 0.2 5.3 0.3 0.63
L1 8.5 0.7 8.6 0.7 8.3 0.9 0.27 5.3 0.3 5.3 0.2 5.3 0.3 0.34
IMW 48.9 2.7 50.2 3.5 50.9 3.8 0.17 38.9 2.9 42.4 4.9 41.7 8.9 0.07
ICW 33.8 2.5 34.8 6.3 34.8 2.9 0.68 26.6 3.1 28.1 6.7 26.6 2.4 0.49
SD: standard deviation; R: right; L: left; IMW: Intermolar width; ICW: intercanine width.
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7. interproximal contacts on an enlarged image. Although the
resolution of the software can be high, it may be difficult to
choose the accurate contact point between 2 teeth or 2 points
for inexperienced examiners [7]. In our study, the examiner was
previously trained and had been using this software for routine
clinical practice as conventional plaster model analysis.
Another point affecting the accuracy of measurements is the
plaster model production and scanning phase [18]. Any vari-
ance in measurements between plaster models and digital
models obtained from plaster dental model scanning or dental
impression scanning should be a result of distortion or an
amount of shrinkage of the alginate impression material
[11,18]. This point is important especially for digital model
production from impression scanning. Coleman et al. [19]
reported significant dimensional changes between dental mo-
dels poured within 1 hour of the alginate impression compared
with pouring 24 hours later. Alcan et al. [20] also suggested that
storing alginate impressions in sealed plastic bags for up to
4 days caused statistically significant deformation of alginate
impressions, although these deformations did not appear to be
clinically relevant during the digital model construction from 3D
scanner. However, this finding was stated for dental model
scanner, while digital model reconstruction from direct impres-
sion scanning can be influenced from these distortions further
than digital models obtained from model scanners. In the
present study, 3D impression scanning and pouring process
were performed at maximum 10 minutes from dental impres-
sion, so distortion or variation on alginate impressions were
avoided and there was no statistically significant difference
between linear measurements between plaster models and
digital models obtained from plaster dental model scanning
and dental impression scanning methods.
The accuracy of dental measurements on digital models
obtained from plaster dental model scanning was also
reported previously [3,7,10,18,21,22]. The findings of this
present study exhibited slight and clinically insignificant differ-
ences at the individual tooth size measurements between
three methods. This result was consistent with previous stud-
ies, which investigated conventional method on plaster mo-
dels vs. digital method on plaster dental model scanning
images [13,23–25]. When the results about accuracy of tooth
size measurements on digital models obtained from impres-
sion scanning method was evaluated, Camardella et al. [9] also
reported high accuracy and reliability of digital models by
impression scanning as with the findings of the present study.
At the transversal dental measurements, there was no signifi-
cant difference at the intercanine and intermolar width meas-
urements on digital models compared to measurements on
plaster model particularly in agreement with other reports,
which suggest that small and clinically insignificant differen-
ces were found between plaster models and digital models
obtained from plaster dental model scanning method
[3,7,21,25]. Although Abizadeh et al. [16] reported statistically
significant difference on transversal dental measurements
between plaster models and digital models obtained from
model scanner, they stated that these differences could not
be clinically significant. Similarly, Leifert et al. [11] measured
the tooth size of maxillary and mandibular arches and com-
pared arch length discrepancies between plaster models and
digital models obtained from model scanner and concluded
that although there was a statistically significant difference in
the space analysis measurements from the maxillary models,
the difference was minimal and apparently not clinically sig-
nificant. They explained the statistically significant difference
with greater variability in the inclination of the anterior teeth
in the maxillary arch as opposed to the mandibular arch. This
study also presents no significant difference at the intercanine
and intermolar width assessment between plaster models and
digital models obtained from plaster dental model scanning
and dental impression scanning methods.
Similar to our tooth size and arch width dental measurements,
Bolton tooth size discrepancy analysis also showed acceptable
repeatability and accuracy for total and anterior proportion at
the digital models obtained from plaster dental model scanning
and dental impression scanning methods [9,26]. This finding
was in agreement with the results of many researchers showing
that no statistically significant difference existed between plas-
ter models and digital models obtained from plaster dental
model scanning or dental impression scanning in terms of
measurements of tooth-size discrepancies with the Bolton anal-
ysis [9,15,18,21,27]. Mullen et al. [25] also concluded that
analysis on e-models could be significantly faster than the
traditional method of digital calipers and plaster models. Like
our digital model construction from plaster models, Brandao
et al. [28] also used 3 Shape®
R-700T scanner and reported that
Bolton analysis performed on digital models from 3 Shape
model scanners was reliable as plaster models with satisfactory
agreement. According to the findings of present study, Bolton
analysis for total and anterior proportion on digital models
reconstructed from both plaster dental model scanning method
and impression scanning method were found reliable and accu-
rate compared to plaster models. The advantages of digital
models obtained from impression scanning are no need for
plaster model pouring, and a saving of plaster material and
pouring time. The reliability and accuracy of dental model
analysis on digital models obtained by impression scanning
has importance in modern orthodontic practice. This is the first
report presenting a comparison of two different digital model
reconstruction methods in terms of accuracy and reliability of
dental model analyses. More studies should be designed for the
investigation of the same digital models to evaluate depth and
height measurements, area and volumetric measurements and
superimposition ability of dental changes on stable reference
structures.
Comparison of dental measurements between conventional plaster models, digital models obtained by
impression scanning and plaster model scanning
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8. Conclusions
Digital measurements of tooth size, arch width and Bolton tooth
size discrepancy on digital models obtained from plaster dental
model scanning and dental impression scanning showed high
accuracy and reliability.
There was no statistically significant difference between direct
measurements on the plaster models with a caliper and digital
measurements on digital models obtained from plaster dental
model scanning and dental impression scanning methods.
Digital models can be alternative to plaster models with clini-
cally acceptable accuracy and reliability of tooth size, arch width
measurements and Bolton analysis.
Funding
The authors did not receive any external funding to perform this
study.
The accompanying manuscript does not include studies on
humans or animals.
Disclosure of interest: the authors declare that they have no competing
interest.
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N. Gül Amuk, E. Karsli, G. Kurt
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article