Dentists use crowns to restore damaged teeth and help patients chew comfortably again. For a crown to succeed, it must fit closely to the prepared tooth. However, if the fit is poor, bacteria can enter the gap between the crown and the tooth, increasing the risk of microleakage, secondary caries, periodontal problems, and premature failure.
As 3D printing becomes more widely used in digital dentistry, researchers are working to understand how simple printing choices can affect the quality of the final restoration. In a study published in the KeAi journal Dental Research , a team of researchers in China investigated how print angle and layer thickness influence the accuracy and fit of permanent resin-based ceramic crowns made with digital light processing, a light-based 3D-printing technology.
"We designed a mandibular first molar crown and printed it at nine different angles, from 90° to 270°, and at two layer thicknesses, 50 and 100 μm," shares corresponding author Shizhu Bai, a researcher at the School of Stomatology, The Fourth Military Medical University. "We then measured how closely each printed crown matched its digital design and how well it fit a prepared tooth model."
The team found that both print angle and layer thickness had significant effects on crown accuracy and fit. "Overall, crowns printed at moderate angles of 150° to 180° performed best, while crowns printed with 50-μm layers showed better trueness and internal fit, and crowns printed with 100-μm layers showed more concentrated deviation distributions and more repeatable results across repeated prints. All crowns in the study remained within the clinically acceptable fit range," says Bai.
Further, the researchers found that printing deviations were not evenly distributed across the crown's inner surface. "Marginal areas tended to shrink inward, whereas occlusal regions were more likely to bulge outwards — this helps explain why a crown may appear acceptable overall but still require adjustment before delivery," adds Bai.
The believe their findings can provide practical guidance for dental 3D printing. "For routine production, a print angle of 150° to 180° combined with a 50-μm layer thickness may offer the best balance between manufacturing accuracy and clinical fit, while a 100-μm layer thickness may be useful when reproducibility is the main priority," Bai emphasizes.
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Contact the author:
Shizhu Bai
State Key Laboratory of Oral Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi Key Laboratory of Stomatology, Digital Dentistry Center, School of Stomatology, The Fourth Military Medical University, Xi'an 710004, PR China. baishizhu@foxmail.com
The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).
Experimental study
Not applicable
Effect of print parameters on the accuracy and fit of 3D-printed resin-based ceramic crowns
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.