Comparison of the marginal and internal fit of provisional crowns produced by additive manufacturing using different parameters

Background This in-vitro study aimed to evaluate the marginal and internal fit of provisional crowns fabricated using additive manufacturing with different production parameters. Methods A master model was prepared by reducing mandibular first molar, and subsequently scanned using a Ceramill Map 600 + digital scanner (Amann Girrbach, Austria). Two provisional restorative materials were investigated: Flexcera Smile Ultra+ (Desktop Health, USA) and VarseoSmile TriniQ (Bego, Germany). A total of 180 provisional crowns were fabricated using two layer thicknesses (50 µm and 100 µm) and three build orientations (0°, 45°, and 90°) with two DLP-based 3D printers (EnvisionTEC Dental, USA; Asiga Max 2, Australia). Marginal and internal fit were evaluated using the silicone replica technique and analyzed under a stereomicroscope (Leica Camera AG, Germany). Statistical analyses of the obtained data were performed using the Shapiro-Wilk test, Tukey post-hoc test, one-way ANOVA, and independent samples t-tests. Results Both layer thickness and build orientation significantly affected marginal and internal fit. Crowns fabricated with 50 µm layer thickness and 45° build orientation demonstrated superior fit in most regions, whereas specimens produced with a 100 µm layer thickness at a 90° orientation showed significantly larger discrepancies in the marginal, cervical, and axial regions (p < 0.001). Conclusions Although manufacturing parameters significantly influenced marginal and internal adaptation, all evaluated provisional crowns exhibited marginal fit values within clinically acceptable limits.