Two-body fatigue wear resistance of 3D-printed composites evaluated using OCT

This study assessed the wear resistance of 3D-printed CAD/CAM composites using optical coherence tomography (OCT). OCT is a non-destructive and clinically applicable imaging technique that enables real-time and precise measurement of wear volume and subsurface changes without radiation exposure. The 3D-printed composites C&B MFH, VarseoSmile CrownPlus, and Nanolab 3D were compared to the CAD/CAM composite milling block, Lava Ultimate, to determine whether their wear resistance was comparable to or exhibited significantly more significant material loss than the CAD/CAM block under cyclic loading in a chewing simulator.

Specimens of the three 3D-printed CAD/CAM composites-C&B MFH, VarseoSmile CrownPlus, and Nanolab 3D-were designed as disks, 3D-printed or milled, then cleaned and polished before undergoing cyclic loading in a chewing simulator for 600,000 cycles. OCT analysis was used to measure wear extent and subsurface crack score. Statistical analysis was performed using one-way ANOVA and Kruskal-Wallis tests with post-hoc Bonferroni comparisons.

Significant differences in wear resistance and crack development were observed among the composites. Lava Ultimate and C&B MFH exhibited the highest wear resistance (0.7 ± 0.4 mm³ and 0.7 ± 0.2 mm³), while Nanolab 3D had the lowest and significantly different wear resistance (1.7 ± 0.8 mm³, p = 0.004). VarseoSmile CrownPlus showed intermediate volume loss (1.0 ± 0.7 mm³) with no significant difference from Nanolab 3D (p = 0.2). For vertical wear extent, Lava Ultimate (215.6 ± 40 μm) and C&B MFH (310 ± 107 μm) had significantly lower wear than Nanolab 3D (546 ± 143 μm, p < 0.001), while VarseoSmile CrownPlus (396 ± 131 μm) was not significantly different from Nanolab 3D (p = 0.8). A similar pattern was observed for cracks, with Lava Ultimate showing significantly different from the 3D-printed composites (p < 0.001). Nanolab 3D exhibited the highest crack formation, showing a significant difference compared to all other materials (p < 0.001), while no significant difference was found between C&B MFH and VarseoSmile CrownPlus (p = 0.5).

In conclusion, the 3D-printed CAD/CAM composites demonstrated varying performance under cyclic loading, comparable or inferior to the CAD/CAM block, with OCT proving useful for evaluating composite wear resistance.