Effect of Material Type and Printing Orientation on the Marginal and Internal Fit of Additively Manufactured Definitive Resin Crowns: A Micro-Computed Tomography Study.

Objective

To investigate the effects of material type and printing orientation on the marginal, axial, and occlusal fit of additively manufactured definitive resin crowns using micro-computed tomography (micro-CT).

Methods

Seventy definitive resin crowns were allocated to 10 groups according to material type (Saremco Crowntec [SC] and VarseoSmile Crown Plus [VP]) and printing orientation (0°, 30°, 45°, 60°, and 90°; n = 7). Crowns were fabricated using digital light processing and evaluated by micro-CT at 26 predefined measurement points. Data were analyzed using generalized estimating equations with a CR2 small-sample correction and Bonferroni-adjusted pairwise comparisons (α = 0.05).

Results

Marginal fit was significantly affected by printing orientation (P = 0.005) and the material × printing orientation interaction (P < 0.001), but not by material (P = 0.703). For axial fit, material, printing orientation, and their interaction were significant (all P < 0.001). Occlusal fit was significantly affected by printing orientation (P = 0.016) and the interaction (P < 0.001), but not by material (P = 0.074). Most material-printing orientation combinations showed marginal gaps below the commonly cited 120 µm clinical threshold; however, SC at 90° and VP at 0° exceeded this threshold.

Conclusions

The effect of printing orientation on the fit of additively manufactured definitive resin crowns was material-dependent and varied according to the evaluated fit region. Material-specific optimization of printing orientation may improve restoration fit.