Abstract
Objectives: To evaluate the effect of engineered micro-textures on the interfacial adhesion of an additively manufactured (AM) resin composite crown material compared to conventional surface treatments.
Methods: Rectangular specimens were fabricated from an AM crown material (VarseoSmile Crown plus) with eight micro-textures (Pin, Sphere, Tube, Fluorite; at 0.25 mm and 0.5 mm scales). Controls included as-printed, milled composite (Tetric CAD), and sandblasted surfaces. Maximum load at failure (N), shear bond strength (SBS), and interfacial fracture energy (GIc) were determined using a chevron-notch test after cementation with a dual-curing resin cement. Data were analysed using ANOVA, post-hoc test, and Weibull analysis. Failure modes were assessed by Stereomicroscopy and Scanning Electron Microscopy.
Results: A significant effect of surface modification on GIc was found (p<0.0001). The Pin 0.5 (102.9 ± 16.9 J/m2) and Fluorite 0.5 (96.6 ± 15.7 J/m2) textures yielded significantly higher (p<0.0001) fracture energy than sandblasted (51.9 ± 26.8 J/m2) and AM control (48.2 ± 18.0 J/m2). The fluorite 0.25 (78.5 ± 12.8 J/m2) also significantly outperformed controls (p=0.0087). Sandblasting provided no significant improvement over the AM control (p>0.99). Weibull analysis confirmed the highest reliability for Fluorite (FLU .5) (β=8.31) and Pin (PIN .5) (β=7.58) textures. Failure analysis revealed a shift from predominantly adhesive failure in controls to mixed and cohesive failures in high-performing textured groups.
Conclusions: Engineered micro-textures, particularly pin and fluorite geometries, significantly enhance the strength and reliability of the adhesive interface to AM resin composite crowns. These predetermined topographies could provide increased micromechanical interlocking and a reproducible alternative to conventional sandblasting.
Clinical significance: This research highlights a new method of enhancing the bond strength of additively manufactured dental crowns by creating micro-textures. The addition of textures could be a more effective and reproducible strategy to improve the clinical performance and predictability additively manufactured dental restorations.