Research and Education
Dimensional accuracy and surface characteristics of 3D-printed dental casts

https://doi.org/10.1016/j.prosdent.2020.07.008Get rights and content

Abstract

Statement of problem

Although studies have reported the accuracy of 3D-printed dental casts, studies addressing cast distortion throughout the complete-arch range are lacking.

Purpose

The purpose of this in vitro study was to evaluate the dimensional accuracy of different areas in complete-arch casts made with various 3D printing methods.

Material and methods

A computer-aided design (CAD) reference cast was modified from a mandibular cast by adding 6 cylinders in the canine, second premolar, and second molar locations and 3 spheres to define a coordinate system. A total of 50 casts were printed with 5 group materials, which included fused deposition modeling (FDM), digital light processing (DLP1 and DLP2), photopolymer jetting (Polyjet), and stereolithography (SLA). After scanning the 3D printed casts, the overall consistency was examined by superimposing them on the CAD reference cast and measuring the deviations. For dimensional accuracy, cylinder top coordinates were extracted from each printed cast, and X-, Y-, and Z-deviations and the 3D deviation were calculated by subtracting the coordinates of the CAD reference cast from the cast values. Statistical analyses were conducted by the Kruskal-Wallis test and the Mann-Whitney post hoc test (α=.05). Surface characteristics were examined with photographs and scanning electron micrographs.

Results

FDM showed more systemic deviations than DLP, Polyjet, and SLA from superimposing analysis (P<.01). In the X-axis, FDM and DLP showed contraction, while Polyjet and SLA showed expansion (P<.01). In the Y-axis, FDM showed forward deviations on the right side and DLP showed contraction (P<.01). Three-dimensional deviation at each cylinder location was lowest in the left canine region, and deviations increased with distance from this site in all groups. The qualitative features of casts varied among 3D printers in terms of shape, surface smoothness, and edge sharpness.

Conclusions

FDM and DLP casts tended to contract, whereas casts in the Polyjet and SLA groups expanded buccolingually and anterioposteriorly. Vertically, deviations were smaller than those in the other directions.

Section snippets

Material and methods

A CAD reference cast was created by using a 3D design software program (Rapidform; Inus Technology Inc) and attaching implant scan bodies to a mandibular dental arch. Six cylinders were placed in the left and right canines, second premolars, and second molars. Three additional reference spheres were placed around the left second molar to establish a coordinate system with which to measure deviations (Fig. 1).

Casts were made from 5 different materials by using 4 printers with different printing

Results

The median trueness values of the 3D-printed casts in each group are shown in Figure 4. The FDM casts had a significantly larger systematic deviation (158.1 μm) than those of the DLP1 (104.4), DLP2 (103.3 μm), Polyjet (99.3 μm), and SLA casts (109.9 μm) (P<.01). No significant differences were found among the other 4 groups (P>.05). In addition, the FDM casts showed a relatively wide range of deviation and prominent striations. The casts of the DLP 1 and DLP 2 groups had minimal deviation in

Discussion

In the present study, the accuracy of 3D-printed casts was analyzed in 2 ways. In the image-merging analysis, the overall deviation (or trueness) was determined and represented as a color map. The FDM casts had a significantly larger deviation than the others in the former analysis, and there were significant differences in the X-, Y-, and Z-axes among the 3D-printed casts in the latter study. Therefore, the null hypothesis was rejected. Although the stone cast is considered the standard, it

Conclusions

Based on the findings of this in vitro study, the following conclusions were drawn:

  • 1.

    The FDM printer was found to be inferior to the other 3D printers for complete-arch dental cast fabrication.

  • 2.

    Deviations at different cylinder locations showed that FDM and DLP casts tended to contract, whereas casts of the Polyjet and SLA groups expanded buccolingually and anterioposteriorly. Vertically, deviations were generally smaller than those in the other directions, especially for the SLA group.

  • 3.

    The

CRediT authorship contribution statement

Ji-Man Park: Conceptualization, Methodology, Validation, Investigation, Data curation, Writing - original draft, Writing - review & editing, Funding acquisition. Jin Jeon: Validation, Investigation, Data curation, Writing - original draft, Writing - review & editing. Jai-Young Koak: Validation, Writing - review & editing. Seong-Kyun Kim: Validation, Writing - review & editing. Seong-Joo Heo: Conceptualization, Validation, Investigation, Data curation, Writing - review & editing, Supervision.

References (45)

  • A.S. Persson et al.

    Digitization of simulated clinical dental impressions: virtual three-dimensional analysis of exactness

    Dent Mater

    (2009)
  • A.J. White et al.

    Analysis of intra-arch and interarch measurements from digital models with 2 impression materials and a modeling process based on cone-beam computed tomography

    Am J Orthod Dentofacial Orthop

    (2010)
  • T.V. Flugge et al.

    Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner

    Am J Orthod Dentofacial Orthop

    (2013)
  • R. van Noort

    The future of dental devices is digital

    Dent Mater

    (2012)
  • F.P. Melchels et al.

    A review on stereolithography and its applications in biomedical engineering

    Biomaterials

    (2010)
  • S.Y. Kim et al.

    Precision and trueness of dental models manufactured with different 3-dimensional printing techniques

    Am J Orthod Dentofacial Orthop

    (2018)
  • S.J. Lee et al.

    Digital vs. conventional implant impressions: efficiency outcomes

    Clin Oral Implants Res

    (2013)
  • T. Miyazaki et al.

    A review of dental CAD/CAM: current status and future perspectives from 20 years of experience

    Dent Mater J

    (2009)
  • F. Beuer et al.

    Digital dentistry: an overview of recent developments for CAD/CAM generated restorations

    Br Dent J

    (2008)
  • M. Vojdani et al.

    Comparison the marginal and internal fit of metal copings cast from wax patterns fabricated by CAD/CAM and conventional wax up techniques

    J Dent (Shiraz)

    (2013)
  • D.T. Pham et al.

    Design for stereolithography

    Proc Inst Mech Eng C

    (2000)
  • G. Bugeda et al.

    Numerical analysis of stereolithography processes using the finite element method

    Rapid Prototyp J

    (1995)

    • Cited by (0)

    Supported by the Technology Innovation Program (20001155) funded by the Ministry of Trade, Industry, and Energy.

    J.-M.P. and J.J. contributed equally to this work.

    View full text
    © 2020 by the Editorial Council for The Journal of Prosthetic Dentistry.