Korean J Orthod.  2016 May;46(3):129-136. 10.4041/kjod.2016.46.3.129.

Evaluation of digital dental models obtained from dental cone-beam computed tomography scan of alginate impressions

• Jiang T
• Lee SM
• Hou Y
• Chang X
• Hwang HS

• KMID: 2164256
• DOI: http://doi.org/10.4041/kjod.2016.46.3.129

Abstract

OBJECTIVE
To investigate the dimensional accuracy of digital dental models obtained from the dental cone-beam computed tomography (CBCT) scan of alginate impressions according to the time elapse when the impressions are stored under ambient conditions.
METHODS
Alginate impressions were obtained from 20 adults using 3 different alginate materials, 2 traditional alginate materials (Alginoplast and Cavex Impressional) and 1 extended-pour alginate material (Cavex ColorChange). The impressions were stored under ambient conditions, and scanned by CBCT immediately after the impressions were taken, and then at 1 hour intervals for 6 hours. After reconstructing three-dimensional digital dental models, the models were measured and the data were analyzed to determine dimensional changes according to the elapsed time. The changes within the measurement error were regarded as clinically acceptable in this study.
RESULTS
All measurements showed a decreasing tendency with an increase in the elapsed time after the impressions. Although the extended-pour alginate exhibited a less decreasing tendency than the other 2 materials, there were no statistically significant differences between the materials. Changes above the measurement error occurred between the time points of 3 and 4 hours after the impressions.
CONCLUSIONS
The results of this study indicate that digital dental models can be obtained simply from a CBCT scan of alginate impressions without sending them to a remote laboratory. However, when the impressions are not stored under special conditions, they should be scanned immediately, or at least within 2 to 3 hours after the impressions are taken.

Keyword

Digital dental model; Alginate impression; Dental cone-beam computed tomography; Dimensional accuracy

MeSH Terms

Adult
Cone-Beam Computed Tomography*
Dental Models*
Humans

Figure

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  Figure 1 The process of creating a digital dental model using a cone-beam computed tomography-scanned alginate impression. A, Stereolithography file was imported into the Rapidform 2006 program (Inus, Seoul, Korea). B, The negative of the impression was converted into the positive form. C, Excessive area over the impression tray was trimmed to complete fabrication of the digital dental model.

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  Figure 2 Linear measurements made on each digital model. A, Incisor to molar; B, intermolar width; C, incisor height.

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  Figure 3 Graphic presentations of time-related changes and comparisons between the materials. There were no statistically significant differences between the materials although the extended-pour alginate material (Cavex ColorChange; Cavex Holland BV, Haarlem, the Netherlands) exhibited a less severe decreasing tendency than the other 2 traditional alginates. A Incisor to molar; B, intermolar width; C, incisor height.

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