IADR Abstract Archives
Role of Superimposition Basis on Evaluation of 3D-Printed Dental Models
Objectives: Parameters of dental model design can affect the efficiency and accuracy of 3D-printing. This project applied digital superimposition tools to investigate the effects of changing the region of the arch used as the basis of the superimposition in evaluating the accuracy of 3D-printed models of different designs. Specifically, the project compared outcomes of superimpositions based on the clinical crowns of the entire arch versus the clinical crowns of the anterior region.
Methods: Dental models were 3D-printed in 9 groups of 13 (n = 117). Base designs included 4 variants: horseshoe, flat plane, trans-palatal bar, and T-bar. Gingival trim variants included full palate and 2 or 7 mm of gingiva. Samples were scanned, digitally trimmed to only the clinical crowns, and superimposed with the input file using either the entire arch or anterior region as the basis for the best-fit superimposition. Results were statistically analyzed using generalized linear mixed models with post-hoc Tukey contrasts where appropriate.
Results: Full arch and anterior superimposition analyses indicated statistically significant differences between groups and a statistically significant bias toward negative deviation or underbuilding. The magnitude of deviation was much greater for anterior superimpositions, consistent with excess compensating curve. The 7 mm horseshoe was the least deviated group for several measures in both analyses. Magnitudes of differences between groups on average were on the order of hundredths of a millimeter, compliant with reported tolerances for orthodontic applications (±0.250 mm).
Conclusions: In both full arch and anterior superimpositions, statistically significant differences exist between dental models produced with different gingival amounts and base designs. The compensating curve appears greater with anterior than full arch superimposition. Therefore, anterior-based superimpositions may be a useful tool for analysis of vertical discrepancies in orthodontic models.
Methods: Dental models were 3D-printed in 9 groups of 13 (n = 117). Base designs included 4 variants: horseshoe, flat plane, trans-palatal bar, and T-bar. Gingival trim variants included full palate and 2 or 7 mm of gingiva. Samples were scanned, digitally trimmed to only the clinical crowns, and superimposed with the input file using either the entire arch or anterior region as the basis for the best-fit superimposition. Results were statistically analyzed using generalized linear mixed models with post-hoc Tukey contrasts where appropriate.
Results: Full arch and anterior superimposition analyses indicated statistically significant differences between groups and a statistically significant bias toward negative deviation or underbuilding. The magnitude of deviation was much greater for anterior superimpositions, consistent with excess compensating curve. The 7 mm horseshoe was the least deviated group for several measures in both analyses. Magnitudes of differences between groups on average were on the order of hundredths of a millimeter, compliant with reported tolerances for orthodontic applications (±0.250 mm).
Conclusions: In both full arch and anterior superimpositions, statistically significant differences exist between dental models produced with different gingival amounts and base designs. The compensating curve appears greater with anterior than full arch superimposition. Therefore, anterior-based superimpositions may be a useful tool for analysis of vertical discrepancies in orthodontic models.