Abstract
Statement of problem
The accuracy of digital scanning for complete dental arch and implant-supported complete-arch
restorations has been reported. However, research addressing the accuracy of digital
scanning methods for complete-arch tooth preparation is lacking.
Purpose
The purpose of this in vitro study was to compare the accuracy of intraoral scanning,
impression scanning, and cast scanning for complete-arch preparation.
Material and methods
Maxillary and mandibular jaw typodonts with 28 teeth prepared for complete crowns
were used as reference casts and digitized as reference data sets with a desktop scanner.
Three digital scanning methods were applied. First, the reference casts were each
scanned 10 times with an intraoral scanner to generate the intraoral scanning group
data sets. Second, the reference casts were each captured 10 times by using polyvinyl
siloxane impression material, and the impressions were scanned with a desktop scanner
to generate the impression scanning group data sets. Third, the impressions obtained
in the impression scanning group were used to make gypsum casts which were then digitized
with a desktop scanner to generate the cast scanning group data sets. Accuracy was
determined by trueness and precision. Three-dimensional deviations of the prepared
arches and anterior and posterior segments were measured from root mean square values
and depicted on color-difference maps. Differences among test groups were analyzed
by using a 1-way ANOVA and the post hoc Bonferroni test for normally distributed data
or the Kruskal-Wallis test with Bonferroni correction for non-normally distributed
data (α=.05).
Results
The trueness of the maxillary arch was significantly higher in the impression scanning
group than in the cast scanning and intraoral scanning groups (P<.05), but no significant differences were found among the 3 groups of the mandibular
arch (P>.05). The precision of both arches was significantly higher in the impression scanning
and intraoral scanning groups than in the cast scanning group (P<.05). Color maps showed horizontal symmetrical displacement in the intraoral scanning
group relative to the reference data sets and within-group unilateral distal-end distortion.
Irregular arch deformations were noted in the impression scanning group, and buccal
and occlusal expansion occurred in the anterior-posterior direction in the cast scanning
group. Pooled data for anterior teeth indicated that the trueness was lowest in the
intraoral scanning group; however, that for the maxillary anterior teeth did not differ,
while that for the mandibular anterior teeth differed significantly among groups (P<.05). For the posterior teeth, deviation was the lowest in the impression scanning
group, and significant differences were noted in both arches among the 3 groups (P<.05).
Conclusions
Of the methods tested, impression scanning was the most accurate for the creation
of a digital cast of a complete prepared arch.
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Article info
Publication history
Published online: March 15, 2021
Footnotes
Supported by the National Natural Science Foundation of China (81701001, 81701003), the Program for New Clinical Techniques and Therapies of Peking University School and Hospital of Stomatology, PR China (PKUSSNCT-19A03), and the National Key Clinical Specialty Construction Project of PR China.
H.G. and X.L. contributed equally to this article.
Identification
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© 2021 by the Editorial Council for the Journal of Prosthetic Dentistry.
