J Adv Prosthodont.  2019 Apr;11(2):138-146. 10.4047/jap.2019.11.2.138.

Accuracy of casts produced from conventional and digital workflows: A qualitative and quantitative analyses

• Abduo J

• KMID: 2444148
• DOI: http://doi.org/10.4047/jap.2019.11.2.138

Abstract

PURPOSE
Comparing the accuracy of casts produced from digital workflow to that of casts produced from conventional techniques.
MATERIALS AND METHODS
Whole arch alginate (ALG) and polyvinyl siloxane (PVS) impressions were taken with stock trays and custom trays, respectively. The ALG impressions were poured with type III dental stone, while the PVS impressions were poured with type IV dental stone. For the digital workflow, IOS impressions were taken and physical casts were produced by 3D printing. In addition, 3D printed casts were produced from images obtained from a laboratory scanner (LS). For each technique, a total of 10 casts were produced. The accuracies of the whole arch and separated teeth were virtually quantified.
RESULTS
Whole arch cast accuracy was more superior for PVS followed by LS, ALG, and IOS. The PVS and ALG groups were inferior in the areas more susceptible to impression material distortion, such as fossae and undercut regions. The LS casts appeared to have generalized errors of minor magnitude influencing primarily the posterior teeth. The IOS casts were considerably more affected at the posterior region. On the contrary, the IOS and LS casts were more superior for single tooth accuracy followed by PVS and ALG.
CONCLUSION
For whole arch accuracy, casts produced from IOS were inferior to those produced from PVS and ALG. The inferior outcome of IOS appears to be related to the span of scanning. For single tooth accuracy, IOS showed superior accuracy compared to conventional impressions.

Keyword

3D printing; Impression; Trueness; Precision; Virtual

MeSH Terms

Jupiter
Polyvinyls
Printing, Three-Dimensional
Siloxanes
Tooth
Polyvinyls
Siloxanes

Figure

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  Fig. 1 Diagrams illustrating the segmentation of the different surfaces. (A) Anterior tooth, (B) Posterior tooth. AS = axial surface, PS = proximal surface, GS = gingival surface, IE = incisal edge, OC = occlusal cusp, and OF = occlusal fossa.

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  Fig. 2 Box plot diagrams comparing the accuracies of the different groups. (A) Trueness, (B) Precision.

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  Fig. 3 Examples of heat maps of different surfaces for each group. (A) ALG, (B) PVS, (C) LS, (D) IOS. The ALG and PVS tend to show distortion at the interdental papillae, occlusal fossae, and gingival surfaces. The LS casts suffered from generalized error of minor magnitude and the casts appeared narrower than the original model. The IOS suffered from widening that primarily affected the accuracy of the posterior segments.

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  Fig. 4 The frequency of deviation of the different surfaces among the 4 groups: (A) Occlusal fossae, (B) Occlusal cusps, (C) Incisal edges, (D) Interdental papillae, (E) Proximal surfaces, (F) Axial surfaces, (G) Gingival surface.

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  Fig. 5 Box plot diagram illustrating the teeth trueness of the different groups.

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  Fig. 6 Box plot diagram illustrating the trueness of different teeth categories of all the groups.

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