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Updated: May 23, 2026
Accuracy in Dental Medicine, A New Way to Measure Trueness and Precision
Published on: April 29, 2014
Volume, precision and trueness of additively manufactured inlay restorations
Andreas Magnus Geyer1, Sarah Katharina Kilian2, David Kiramira1
1Department of Periodontology and Operative Dentistry, University Medical Center of the Johannes Gutenberg-University Mainz, Augustusplatz 2, 55131, Mainz, Germany.
Objectives:
Dental resins for single-tooth restorations undergo shrinkage during manufacture. The shrinkage can be compensated for by adjusting the internal tooth-restoration gap. This study examines the volume precision and trueness of additive manufactured inlays based on different gap widths.
Methods:
Indirect restorations were fabricated with a dental resin (VarseoSmile Crown plus) on a digitised molar with a mesio-occlusal-distal cavity. A total of 42 inlays, with spacers ranging from 0 to 130 µm, were printed in 10 µm increments. Three print batches (P1, P2 and P3) were produced for each gap width. The printed inlays were digitised using an intraoral scanner. To evaluate volume precision, the intraclass correlation coefficient (ICC) was calculated. Trueness was analysed in relation to initial planning with a paired t-test.
Results:
The printed inlays exhibited a mean shrinkage of 6.2% compared to the planned volumes, and the mean difference in the width of the internal gap was 41 ± 9 µm. All printed results differed significantly from the planned inlays in terms of volume measurement (p < 0.001). There were no significant differences in terms of volume between the three print batches, nor the mean gap widths between teeth and restorations. The ICC for the volume precision measurement was 0.991.
Conclusions:
The amount of volume shrinkage that occurs during 3D printing is consistent. Adjusting the width of the spacer can compensate for the volume loss.
Clinical Relevance:
Additively manufactured inlays undergo consistent volume shrinkage, which may impact their fit. Examining the distances between the planned and printed inlays revealed that there is a minimum offset at which the restorations could be inserted. The combination of material and 3D printer resulted in repeatable precise prints. The fit of indirect restorations can be predictably improved by coordinating intraoral scanners, 3D printers and printing materials.
