| Groups | Description |
| NC | Conventional heat-cure acrylic resin (PMMA) without additives as control. |
| N1 | Conventional heat-cure acrylic resin (PMMA) with 1% TiO2 oxide nano-fillers powder. |
| N5 | Conventional heat-cure acrylic resin (PMMA) with 5% TiO2 oxide nano-fillers powder. |
| HC | High Impact heat-cure acrylic resin (PMMA) without additives as control. |
| H1 | High Impact heat-cure acrylic resin (PMMA) with 1% TiO2 oxide nano-fillers powder. |
| H5 | High Impact heat-cure acrylic resin (PMMA) with 5% TiO2 oxide nano-fillers powder. |