Development of the Novel Filler-Dispersed Resin Composite for Additive Manufacturing

Objectives: This study aimed to develop novel filler-dispersed resin composite for additive manufacturing. Mechanical properties (MP) and physicochemical property (PP) were evaluated.
Methods: STL data for 3D printing of bar samples were created using ChiTuBox software. Precursor for additive manufacturing was prepared via mixing TEGDMA-UDMA (1:1 ratio), photo-initiator (BAPO) and silica filler according to the experimental group. There were 2 types of filler and 4 percentages for each filler, (A) microfiller: 20%; 40%; 60%; and 70%, (B) nanofiller: 10%; 20%; 30%; and 40%. Unfilled resin was used as control. Samples were fabricated by 3D printer (n=36) and divided into 3 subgroups: (a) immediately received MP (flexural strength (FS), flexural modulus (FM) and Vickers hardness (VH)) evaluation; (b) immersed in water for 1 month before MP evaluation; and (c) received one-month PP (water-sorption) evaluation. Data were analyzed by one- or two-way ANOVA followed by Tukey’s test (p = 0.05).
Results: For both filler types, higher filler-content groups demonstrated better MP and PP. On the contrary, higher filler-content precursors also had higher viscosity leading to difficulty in precursor manipulation and voids. For microfiller, 60% and 70% groups demonstrated best MP and PP. For nanofiller, 30% and 40% groups demonstrated best MP and PP. Water-immersion decreased FS and VH, but not FM for both filler types. Comparing between same filler-content groups, microfiller groups exhibited higher VH, lower FM and water-sorption than nanofiller groups but FS was not different. Overall, 70%-microfiller group had the best MP (FS = 178.59±14.9MPa, FM = 7.83±1.34GPa and VH = 82.11±1.94) and PP (water-sorption = 19.5±0.81µgmm^-3) among all groups.
Conclusions: Microfiller groups showed comparable or better properties than nanofiller groups. For both types of filler, higher filler content tends to demonstrate better mechanical and physicochemical properties. Material seems promising and is worth further research and development.