The influence of filler load in 3D printing resin-based composites

Objective: To evaluate the influence of the barium glass (BG) filler in 3D printing resin -based composites for restorative structures. Methods: Experimental 3D printing resin -based composites were formulated with UDMA 70%wt, Bis-EMA 20% wt, and TEGDMA 10%wt. Photoinitiators TPO and DFI (2%wt) were used. BG was incorporated at 40%wt and 50%wt. 0%wt BG was used as negative control and the VarseoSmile Crown plus (Bego) was used as a commercial control. Specimens were printed using a 3D printer. Subsequently, specimens were washed and submitted to post -curing with 405 nm at 60 degrees C for 2 x 20 min at FormCure (FormLabs). 3D printing resin -based composites were evaluated by flexural strength, degree of conversion, softening in solvent, radiopacity, and cytotoxicity against gingival fibroblasts. Data were statistically analyzed using one-way ANOVA ( alpha = 0.05). Results: No significant differences in flexural strength were showed between BG40% (90.5 +/- 5,4 MPa), BG50% (102.0 +/- 11.7 MPa) and VA (105.2 +/- 11.7 MPa). Addition of 40% and 50% of BG showed no influence in the degree of conversion compared to VA (p > 0.05). All groups showed softening in solvent after immersion in ethanol (p < 0.05). All groups showed more than 1mmAl of radiopacity. BG50% showed significantly higher radiopacity (2.8 +/- 0.3 mmAl) than other groups (p < 0,05). Cytotoxicity evaluation showed gingival cell viability higher than 80% for all groups. Significance: Addition of up to 50%wt of barium glass in experimental 3D printing resin -based composites showed promising results for long-term restorative structures.