Effect of wall thickness on shape accuracy of hollow zirconia artificial teeth fabricated by a 3D printer
Hiro Kobayashi1, Franz Sebastian Schwindling2, Akinori Tasaka1
1Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan.
Purpose:
This study aimed to analyze how the wall thickness of 3D-printed hollow zirconia teeth affects shape accuracy.
Methods:
Datasets with measurement points were created for different artificial teeth resembling the mandibular right first molar (Geomagic Design X, 3D Systems). Reference distances were 9.8 mm for mesio-distal direction (M-D), 10.9 mm for bucco-lingual direction (B-L), 7.0 mm for MB-BB and DB-BB, and 4.5 mm for ML-LB and DL-LB. The outer geometry was identical for all artificial teeth with wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia teeth were fabricated using a 3D printer (CeraFab 7500 Dental, Lithoz) for each group and sintered before support removal. After performing analog distance measurements using a micrometer screw, the digital distance measurements and angular deviations between measurement points on 3D scans were analyzed. Possible effects were investigated using nonparametric ANOVA, followed by Tukey's honest significant difference (HSD) test for multiple comparisons.
Results:
The shape accuracy was acceptable for artificial teeth with wall thicknesses of ≥0.5 mm. The largest distance deviation was observed for a wall thickness of 0.3 mm. In particular, DB-BB showed a median deviation of >56.2 µm, which is significantly larger than that for other test groups, ranging from 7.4-9.5 µm (P < 0.05). In most cases, angular deviations were the largest for teeth with 0.3-mm wall thickness (11.6°) and remained below 5.0° for the other test groups.
Conclusions:
Acceptable accuracy was obtained for artificial teeth with wall thicknesses of at least 0.5 mm.
