Biomechanical properties of a 3D printing polymer for provisional restorations and artificial teeth

To characterize a resin-based polymer used for 3D printing (3D) provisional restorations and artificial teeth by evaluating relevant material's properties (flexural strength (σf), elastic modulus (E), water sorption (Wsp) and solubility (Wsl)) and biocompatibility, and comparing to a bis-acryl composite resin (BA) and a heat-cured acrylic resin (AR).

Structures were fabricated from 3D, BA and AR. Bar-shaped specimens (n = 30) were submitted to three-point flexure (in 37ºC water and constant displacement rate: 1 ± 0.3 mm/min) until fracture to calculate σf and E. Additional specimens (n = 30) were aged in 37ºC distilled water for six months before testing for σf. Disc-shaped specimens (n = 5) were dried in desiccators and oven until weight stability was reached, then they were immersed in distilled water for seven days, weighed and submitted to the drying process to obtain Wsp and Wsl. SRB and MTT assays were used to evaluate biocompatibility. Data were statistically analyzed using Kruskal Wallis, Student-Newman-Keuls (α = .05), and Weibull distribution. ANOVA and Tukey (α = .05) were used to evaluate the biocompatibility data.

3D structures showed higher σf than AR after aging. The BA showed the lowest values for σf and E, at baseline and after aging. All materials showed Wsp and Wsl values within the recommended standard values. AR structures showed lower cell viability (71.9%) than 3D (92.9%) and BA (90.8%) when using the SRB test. No difference was found when using MTT (p > .05).

The evaluated polymer-based 3D printing material showed adequate biomechanical behavior for using as a provisional restoration and artificial teeth.