Characterization of 3D printed composite for final dental restorations

Abstract

Objectives This study evaluated the surface, mechanical properties, and optical behavior of a 3D printing resin comparing it with a machinable resin composite. Materials and Methods Specimens of different sizes and shapes were either printed (Vitality, Smart Dent) or machined (Grandio Blocs, Voco GmbH) resin composites with similar composition were prepared. Surface and mechanical characterization were performed with Knoop hardness, flexural strength (three-point-bending), elastic modulus tests. The wear of the tested materials was evaluated against steatite antagonists. The optical properties stability (color change, ΔE_00, and translucency, TP₀₀) were observed after staining in red wine. In addition, the bond strength of the resin composites to two resin cement protocols were investigated with microshear bond strength tests at baseline and after thermocycling. Scanning electron microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) was used for microstructural and chemical characterization. Statistical analyses were performed with t- and ANOVA tests. Results Hardness values (132.76 (16.32) KH- Grandio and 35.87 (2.78) KH - printed), flexural strength (172.17 (26.99) MPa - Grandio and 88.69 (8.39) MPa - printed) and color/translucency change of 1.86 (0.31)/0.06 - Grandio and 3.73 (0.36)/9, 16- printed and depth of wear (24.97 mm (3.60)- Grandio and 7.16 mm (2.84) - printed) were statistically different. No statistical differences were observed for mean roughness (Ra) between materials. For bond strength, mean values (MPa) for non-aged and aged groups were respectively 21.76 (6.64) / 31.9 (12.66) for Bifix cement (Voco GmbH, Cuxhaven, Germany) and 26.75 (5.14) / 24.36 (6.85) for Variolink cement (Ivoclar Vivadent, Schaan, Liechtenstein) in Vitality and 17.79 (3.89) / 9.01 (3.36) ) for Bifix cement and 22.09 (6.55) / 11.01 (3.77) for Variolink cement in Grandio. The material (p < 0.001) and aging (p < 0.003) factor did affect bond strength but the cement factor did not (p = 0.202). No statistical differences were observed for mean roughness (Ra) between materials. The better dispersion and larger size of the inorganic particles in the Grandio were contrasted with the clustered smaller particles of Vitality, under SEM. Results The mechanical properties and color stability of the machinable resin were superior to those of the printed resin, probably due to the greater amount and dispersion of inorganic particles in the machinable resin, but bond strength after aging was stronger and more stable in the printed resin. Clinical Relevance: This study aims to evaluate the possibility of the use of printed composite resin restorations, which can serve as a reference to corroborate its use or to indicate where the manufacture of printed restorations should be improved for the marketplace.