Three-dimensionally printed and milled composite materials for definitive restorations. Part 1: Effect of aging on the mechanical properties

AbstractStatement of problemEvidence regarding the mechanical properties of 3-dimensionally (3D) printed and computer-aided design and computer-assisted manufacturing (CAD-CAM) composite materials is limited. A better understanding of how these materials perform under aging conditions will help clinicians make more informed decisions when selecting materials for specific clinical scenarios.PurposeThe purpose of this in vitro study was to evaluate and compare the effect of aging on flexural strength (FS), modulus of elasticity (E), and Vickers hardness (VHN) of 3D printed and milled materials.Material and methodsBar-shaped specimens (n=20, 14×2×2 mm) and disk-shaped specimens (n=10, Ø15×3 mm) were fabricated using 3D printed materials (Varseosmile Crown Plus; BEGO (VSC), Crowntec; Saremco Print (CWT), Biocrown; Prizma (BCN), Ceramic Crown; SprintRay (CCN), and Voxel Print; FGM (VXP)) and milled materials (Cerasmart; GC (CSM), Brilliant Crios; Coltène (BCR), and Enamic; Vita (ENA)). Half of the specimens (both bar and disk-shaped) were thermocycled for10 000 cycles between 5 and 55 °C. A 3-point bend test was used to measure FS (MPa), and E (GPa). VHN was assessed with a load of 4.9 N and a dwell time of 20 seconds. Data were analyzed using 2-way ANOVA followed by the Bonferroni post hoc test (α[jls-end-space/]=.05).ResultsAging had a negative impact on the FS, E, and VHN values of 3D printed and milled materials. From milled materials, just ENA presented FS values significantly lower after aging (P<.001). The highest and lowest FS values were found in BCR and BCN, respectively (193.6 ±6.7 and 108.4 ±11.3) in the nonaging groups. ENA showed the highest E values (10.2 ±0.9 and 12.4 ±1.1) for both aging and nonaging groups (P<.001). For VHN, ENA showed the highest value (132.3 ±6.1) in the nonaging group (P<.001). Milled materials showed higher E and VHN values than 3D printed ones.ConclusionsThe fabrication method may affect the mechanical properties. The 3D printed materials exhibited lower mechanical properties than milled materials, though thermocycling adversely affected all materials, particularly ENA among the milled materials.