Table 1. Materials grouping.

	Material	Basic chemical structure	Manufacturer
Zirconia	Prettau® 2 Dispersive® (PRT)	unknown	Zirkonzahn GmbH, Bruneck, Italy
Highly translucent zirconia	Prettau® 4 Anterior® Dispersive® (PRTA)	unknown	Zirkonzahn GmbH, Bruneck, Italy
Zirconia-reinforced lithium silicate ceramic	Vita Suprinity, (VS)	SiO2 (56-64%), ZrO2 (8-12%), Li2O (15-21%), La2O3 (0.1) and Pigments (< 10%)	Vita Zahnfabrick, Bad Säckingen, Germany
lithium disilicate ceramic	IPS e.max CAD (E.max)	SiO2 (57–80%), Li2O (11-19%), K2O (<13%), P2O5 (<11%), ZrO2 (<8%), ZnO (<8%), Al2O3<5%, MgO(<5%) and coloring oxides	Ivoclar Vivadent, Schaan, Lichtenstein