Three Body Wear of 3D-printed Materials

Objectives: The three body wear of 3D printed temporary materials (3Delta exp., Nextdent-C&B, Freeprint temp), one temporary CAD/CAM PMMA material (Telio CAD) and a clinically well established conventional resin based composite (Tetric EvoCeram) as the control material was simulated with the ACTA-machine.
Methods: 3Delta exp., Nextdent-C&B, Freeprint temp were printed with a D20II 3D printer (Rapidshape/Heimsheim/Ger). The PMMA specimens were cut out of Telio CAD blocks. Specimens (N=8) were fixed adhesively in an ACTA sample-holder-wheel, Tetric EvoCeram was applied directly and light cured. The three body wear was simulated with an ACTA-machine. A millet seed suspension was used as the abrasive medium. The samples were subjected to 200,000 cycles of three-body-wear using a contact force of 15N between the opposing surfaces. The abrasive medium was renewed every 50000 cycles. The amount of wear was measured with a 3D scanner (LaserScan 3D/Willytec/Munich/Ger). Data were evaluated with the software Match3D and statically analysed (R CRAN, ANOVA, Post-hoc-test: Tukey, p<0.05). The surface of the specimens was examined with a FE-SEM (DSM 982, Zeiss/Oberkochen/Ger).
Results: The average mean wear ranged from 50-257µm. After 200000 cycles Tetric EvoCeram and 3Delta exp. had significantly lower wear in comparison to the other materials. The SEM revealed that 3Delta exp. had a higher filler proportion.
Conclusions: The filler content influences the ACTA wear of materials for 3D printers or CAD/CAM machines. While most current composite materials for this purpose have a low filler load, which qualifies the materials for temporary use only, one material for 3D printing has an optimized composition which would qualify the material for longer clinical service time considering wear as the outcome variable.