Study finds 3D printing more accurate than milling when it comes to dental crowns

Anisha Hall Hoppe, Dental Tribune International

Wed. 24. August 2022

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SENDAI, Japan: Using the exact same dataset and an industrial 3D digitiser to identify deviations, researchers at Tohoku University Graduate School of Dentistry in Japan found that producing a crown by digital light processing (DLP) 3D printing results in a better-quality product than can be achieved through milling.

CAD/CAM-produced milled crowns have proved a popular alternative to traditional metallic restorations in recent years, thanks to the better wear and aesthetic qualities of resin-composites. However, the new study indicates that advances in DLP printing can offer dentists a far better product in terms of less wastage and higher accuracy than has previously been available.

The differences in accuracy between the original dataset used for crown production in the study and the data scanned from the products produced through either DLP 3D printing or milling methods can be seen in this colour map. (Image: Tohoku University)

Compared with the milled crowns created during the study, the DLP-printed crowns were consistently more accurate and had fewer marginal discrepancies. The researchers noted that, particularly at the crown cusps, the milled crowns had a higher rate of dimensional deviations and that, when offset correction was attempted on the internal surfaces of the milled products that had negative deviations, grooves would result.

DLP-based 3D printing achieved a higher level of dimensional fitting accuracy and high trueness, regardless of the abutment shape. When it comes to milling, the trueness is very dependent upon the material properties, and those which are more brittle, such as ceramics and polymer-infiltrated ceramics, are prone to chipping during processing, meaning that too much milling can result in a lower-quality piece.

DLP also provides a broader possible range of fitting accuracy than can be provided by milling.

The researchers noted that future studies could evaluate the fracture resistance and biocompatibility of 3D-printed crowns as permanent prostheses and that additional research utilising different printing parameters and fabrication systems would be useful.

The study, titled “Comparison of the accuracy of resin-composite crowns fabricated by three-dimensional printing and milling methods”, was published online on 6 July 2022 in Dental Materials Journal, ahead of inclusion in an issue.