ABSTRACT
INTRODUCTION: This study aimed to investigate the effect of digitally designed aligner thickness on the thickness of the corresponding 3-dimensional (3D)-printed aligner. METHODS: Digitally designed aligners of 3 different thicknesses (0.500 mm, 0.750 mm, and 1.000 mm) were 3D printed in 2 different resins-Dental LT (n = 10 per group) and Grey V4 (n = 10 per group)-using a stereolithography format 3D printer. The Dental LT aligners were coated with a contrast spray and scanned with an optical scanner. The Grey V4 aligners were scanned before and after the application of the spray. Aligner scans were superimposed onto the corresponding digital design file. Average wall thickness across the aligner for each specimen was measured with metrology software. RESULTS: Superimpositions showed that 3D-printed aligners were thicker overall than the corresponding design file. The Dental LT aligners had the largest thickness deviation, whereas the Grey V4 without spray had the smallest. For the 0.500-mm, 0.750-mm, and 1.000-mm groups, Dental LT average thickness deviation from the input file was 0.254 ± 0.061 mm, 0.267 ± 0.052 mm, and 0.274 ± 0.034 mm, respectively, and average thickness differences between the Grey V4 with and without spray was 0.076 ± 0.016 mm, 0.070 ± 0.036 mm, and 0.080 ± 0.017 mm, respectively. These results indicate that the excess thickness in the Dental LT groups could not be attributed to spray alone. CONCLUSIONS: Fabrication of clear aligners directly by 3D printing with the workflow applied resulted in an increased thickness that may deleteriously affect the clinical utility of the aligners.
Subject(s)
Printing, Three-Dimensional , Stereolithography , WorkflowABSTRACT
INTRODUCTION: This study aimed to investigate the effect of print orientation and ultraviolet (UV) light curing duration on the dimensional accuracy of a clear aligner design fabricated directly using 3-dimensional (3D) printing. METHODS: A master clear aligner design file was 3D printed on a stereolithography printer using 3 different build angles with respect to the build platform: parallel (Horizontal), perpendicular (Vertical), and 45° (45-Degree) (n = 10/group). The 45° orientation then was used to print aligners for 3 postprint processing treatment groups: 0 minutes of UV light and heat exposure (No Cure); 20 minutes of UV light exposure at 80oC (20 Minute), and 40 minutes of UV light exposure at 80oC (40 Minute) (n = 10/group). Each part was digitally scanned and superimposed with the input file for 3D deviation analysis. A generalized linear mixed model and post-hoc Tukey contrasts were applied for statistical analysis. RESULTS: Difficulties were encountered in optical scanning of 3D-printed aligners, resulting in the exclusion of some samples and the No Cure group from the analysis. The average positive and negative deviations were not statistically significantly different among the print orientations, and postprint processing conditions were analyzed and fell within limits of clinical acceptability (0.250 mm). Color deviation maps illustrated localized areas of dimensional deviation that may affect the clinical utility of the printed aligner design. CONCLUSIONS: The print orientation and postprint curing duration have little effect on the overall accuracy of the 3D-printed aligner design under the conditions investigated. However, the potential effects of location-specific deviations on the clinical utility of 3D-printed aligners should be considered in future studies.