Impact of Nanoparticle Addition on the Surface and Color Properties of Three-Dimensional (3D) Printed Polymer-Based Provisional Restorations.

This study aimed to evaluate and compare the impact of additives such as ZrO 2 and SiO 2 nanoparticles (ZrO 2 NP or SiO 2 NP) on the hardness, surface roughness, and color stability of 3D printed provisional restorations. Two hundred samples in total were printed using 3D printed resins (ASIGA, and NextDent). Each resin was modified with ZrO 2 NPs or SiO 2 NPs in two different concentrations (0.5 wt% and 1 wt%), while one group was kept unmodified (n = 10). Disc-shaped (15 × 2.5 mm) samples were designed and printed in accordance with the manufacturer's recommendation. Printed discs were evaluated for color changes through parameters CIELAB 2000 system (ΔE 00 ), hardness using Vickers hardness test, and surface roughness (Ra) using a noncontact profilometer. After calculating the means and standard deviations, a three-way ANOVA and Tukey post hoc test were performed at α = 0.05. The addition of ZrO 2 NPs or SiO 2 NPs to ASIGA and NextDent resins significantly increased the hardness at a given level of concentration (0.5% or 1%) in comparison with pure ( p < 0.001), with no significant difference between the two modified groups per resin type ( p > 0.05). The highest hardness value was detected in 1% ZrO 2 NPs with 29.67 ± 2.3. The addition of ZrO 2 NPs or SiO 2 NPs had no effect on the Ra ( p > 0.05), with 1% ZrO 2 NPs showing the highest value 0.36 ± 0.04 µm with NextDent resin. ZrO 2 NPs induced higher color changes (∆E 00 ), ranging from 4.1 to 5.8, while SiO 2 NPs showed lower values, ranging from 1.01 to 1.85, and the highest mean ∆E 00 was observed in the 1% ZrO 2 NPs group and NextDent resin. The incorporation of ZrO 2 NPs and SiO 2 NPs in 3D printed provisional resins increased the hardness without affecting the surface roughness. The optical parameters were significantly affected by ZrO 2 NPs and less adversely affected by SiO 2 NPs. Consequently, care must be taken to choose a concentration that will improve the materials' mechanical performance without detracting from their esthetic value.