A Proposed In Vitro Methodology for Assessing the Accuracy of Three-Dimensionally Printed Dental Models and the Impact of Storage on Dimensional Stability

Li Hsin Lin,Joshua Granatelli,Khaled E. Ahmed,Derek Smith,Frank Alifui-Segbaya,Laura Drake

doi:10.3390/app11135994

Abstract

The objective of this study was to propose a standardised methodology for assessing the accuracy of three-dimensional printed (3DP) full-arch dental models and the impact of storage using two printing technologies. A reference model (RM) comprising seven spheres was 3D-printed using digital light processing (MAX UV, MAX) and stereolithography (Form 2, F2) five times per printer. The diameter of the spheres (n = 35) represented the dimensional trueness (DT), while twenty-one vectors (n = 105) extending between the sphere centres represented the full-arch trueness (FT). Samples were measured at two (T1) and six (T2) weeks using a commercial profilometer to assess their dimensional stability. Significant (p < 0.05) contraction in DT occurred at T1 and T2 with a medium deviation of 108 µm and 99 µm for MAX, and 117 µm and 118 µm for F2, respectively. No significant (p > 0.05) deviations were detected for FT. The detected median deviations were evenly distributed across the arch for MAX at <50 µm versus F2, where the greatest error of 278 µm was in the posterior region. Storage did not significantly impact the model’s DT in contrast to FT (p < 0.05). The proposed methodology was able to assess the accuracy of 3DP. Storage significantly impacted the full-arch accuracy of the models up to 6 weeks post-printing.

Highlights

Whether fully digital or hybrid, the digital workflow offers a valuable opportunity for cost-effective and streamlined delivery of dental care
The objective of this study was to propose a standardised methodology for assessing the accuracy of 3D printed full-arch dental models and the impact of storage on the dimensional stability using two commercially available 3D printing systems
The reference model was based on a previously published protocol [13] in the form of a horseshoe-shaped model that fits in a standard, medium-sized dental impression stock tray to mimic the dimensions of the dental arch

Summary

Introduction

Whether fully digital or hybrid, the digital workflow offers a valuable opportunity for cost-effective and streamlined delivery of dental care. Is part of the digital workflow, which is being adopted into the dental industry at a rapid rate [1]. The fabrication of 3D printed dental models for single crowns, fixed and removable partial dentures, surgical guides, orthodontic aligners, and treatment planning are examples of the adoption of this technology in routine practise [4,5]. Stereolithography (SLA) and digital light processing (DLP) are common photopolymerisation-based 3DP systems [3,7,8]. SLA involves galvanometer mirrors that direct ultraviolet light to selectively polymerise the monomers point by point across the x-y axis before the build platform moves into the z-axis to incrementally build the appliance [1,9]. DLP utilises micromirrors to direct the projector light to polymerise the entire x-y layer all at once, resulting in a reduced production time compared to SLA [1,10]

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