Evaluating the accuracy between hollow and solid dental aligner models: a comparative study of printing technologies

Objective To evaluate the accuracy between hollow and solid dental models produced using a StereoLithography Apparatus (SLA), Digital Light Processing (DLP), and PolyJet 3D printing technologies.Materials and methods Hollow (of 1 mm, 2 mm, 3 mm shell thicknesses) and solid maxillary models were produced using SLA, DLP, and PolyJet printers. To determine the accuracy of the tested models and deviations from the reference models, 3D digital superimposition was performed. For a detailed analysis, the dental arch was subdivided into five regions which yielded root mean square (RMS) values post-registration. Six different RMS values were generated, one for the total dental arch and one for each of the five individual regions. One-Way ANOVA analysis was applied for intergroup comparisons, and post hoc comparisons were conducted using the Tukey test. The significance of the deviation of RMS values from zero was evaluated through the one-sample t test.Results The PolyJet printer produced models with the least deviation for the total arch, while the SLA printer showed the greatest deviation. The DLP printer produced models with the least deviation for the hollow designs in the anterior region, while the SLA printer produced models with the least deviation of the solid design. The PolyJet printer showed the least deviation for both hollow and solid designs of 2 mm and 3 mm shell thicknesses in the molar regions. Except for the 1 mm shell thickness hollow design on the right side, the PolyJet printer showed the highest accuracy in the premolar-canine regions.Conclusion Accuracy varies in the posterior and anterior regions of the dental arch as a result of different shell thicknesses produced by 3D printing technologies. The clinician should select a design that is appropriate for the intended 3D printing technology based on use and required accuracy.