Abstract: Objective: The study aimed to improve the fabrication process of orthodontic-restorative resin crowns from manual stacking method into CAD/CAM milling method, so as to achieve the effect of completely replicating the shape of crowns. Methods: The dentitions were scanned, and the temporary crowns was digital designed. The PMMA resin tray was digitally milled, and the resin crowns was sent to the clinic for intraoral trial. After adjustment, the resin crowns was scanned and the scan data was saved so that it could be manufactured later. The resin crowns was then returned to the clinic and cemented. Questionnaires were issued to physicians simultaneously to evaluate the satisfaction of retention, insertion time and adjustment convenience. In order to verify that another resin crown (Crown-02), which is identical to the resin crown cemented (Crown-01), can be milled with the scan data, the consistency of both crowns was verified. The PMMA resin tray was digitally milled to obtain Crown-02, and the two crowns were scanned for 3D deviation analysis. Results: A total of 21 crowns were included and the clinical effect was good. The result of dentists’ satisfaction was 92.9% for crown retention, 100% for wearing time, and 100% for adjustment convenience. The average deviation between the modified crown and the re-milled crown was 0.032±0.064mm, and the RMS value was 0.129±0.063mm. Conclusion: In the study, the CAD/CAM milling resin crowns can meet clinical requirements, and can be milled again to be exactly the same as the original resin crowns when needed, so as not to affect the orthodontic treatment.

Key words: resin crown, computer aided design/computer aided manufacturing (CAD/CAM), orthodontic tooth restoration, orthodontic attachment, three-dimensional deviation analysis