Dimensional Change In 3D Printed Casts at Various Processing Stages

Objectives: Since 3D model production is accomplished in several stages, this study’s objective was to measure dimensional change occurring at each stage.
Methods: A maxillary dentoform was scanned and the CAD file modified to produce clearly identifiable measuring marks on the cusp tips of canines (6,11) and distobuccal cusps of second molars (2, 15). Two groups (n=8) were printed on a stereolithography printer (Form 2, dental model resin), one group with supports (S) and one with no supports (NS). Six baseline linear distance measurements were taken between pairs of teeth (2-15,2-11,2-6,6-11,6-15,11-15) within 12 hours post printing. Consistent with recommended processing, subsequent measurements were made following 1 hour UV exposure, 1 hour 60C heat and following supports removal (S group only). Means, SEs were calculated, group comparisons accomplished with ANOVA/Tukey (p<0.05).
Results: See Table. UV exposure produced little change in dimension for any measurement (p>0.05), whereas heat produced the highest significant shrinkage for all measurements (p<0.05). Supports removal generated intermediate dimensional change, ranging -28 to -140 µm, with cross-arch measurements being largest. When all steps were combined, total dimensional change ranged from -108 µm to -178 µm for NS models and -163 µm to -390 µm for S models (p<0.05 for each measurement).
Conclusions: Post-printing heating produced the greatest shrinkage, with cross-arch distances being most affected.