Milling Versus Printing: The Effect of Fabrication Technique on the Trueness and Fitness of Fabricated Crowns (A Comparative In Vitro Study)

Background/Objectives: Computer-aided manufacturing techniques are divided into subtractive (milling) and additive (3D printing) techniques. The accuracy of both techniques is measured only indirectly by testing the fabricated restorations. However, the role of the fabrication technique is masked by the differences in the materials used. Hence, this study used the same printing resin to print crowns and blocks for milling. Methods: Ten maxillary first premolars were prepared for full crowns and scanned with Primescan Connect IOS, and then crown restorations were designed using Exocad. A CAD/CAM block equal to size C14 was designed in CAD software (Microsoft 3D Builder) (Version 18.0.1931.0). The designed crowns and blocks were printed using three hybrid ceramic materials, namely, Ceramic Crown (SprintRay), Varseosmile Crown plus (Bego), and P-crown (Senertek), using a SprintRay Pro95S 3D-printer. The printed blocks were then used to fabricate the designed crowns using an In-Lab MCXL milling machine. The trueness and marginal and internal gaps of the crowns were then measured using Geomagic Control X metrology software (Version 2022.1). Statistical analysis was performed using the Kruskal–Wallis test, Dunn’s test, one-way ANOVA test, and Tukey’s HSD test. Results: Generally, the milled crowns showed significantly higher trueness but lower fitness than their 3D-printed counterparts (p < 0.05). A significant reverse correlation was found between the trueness and fitness of the fabricated restorations. Conclusions: The fabrication technique significantly influenced the accuracy of the hybrid ceramic crowns. Milling offered superior trueness, whereas 3D printing resulted in better internal and marginal adaptation.