Select Physical and Mechanical Properties of Three Machinable Ceramic Materials

Objective: To measure select physical and mechanical properties of three machinable ceramic materials (IPS Empress CAD, Ivoclar Vivadent; VITABLOCS Mark II, Vident; Paradigm C, 3M ESPE). Methods: The properties tested were hardness (VH) [using Vickers hardness], flexural strength (FS) and modulus (FM) [with three-point bending], fracture toughness (FT) [with Vickers hardness indentation], and coefficient of thermal expansion (CTE) [using a thermomechanical analyzer]. For each of the materials, 25 specimens were fabricated, except for coefficient of thermal expansion where n=5. Data were analyzed using one-way analysis of variance and Tukey's Studentized Range Test (significance level = 0.05). Results: Mean values (st dev) are given in the table. The tested ceramic materials differed significantly in all the properties measured. VITABLOCs Mark II was the hardest of the three materials, and IPS Empress CAD had the greatest flexure strength, flexural modulus, and fracture toughness. Conclusions: Significant differences in physical and mechanical properties exist among the millable ceramic materials tested.

Material	VH	FS (MPa)	FM (Gpa)	FT (Mpa•m1/2)	CTE (x 10-6/°C)
IPS Empress CAD	519.9 (6.2)   B	137.51 (3.34)   A	16.10 (5.94) A	2.18 (0.30) A	9.90 (3.02) B
VITABLOCS Mark II	569.3 (10.2) A	94.08 (14.21) C	8.65 (2.24) B	1.37 (0.22) B	8.60 (1.47) B
Paradigm C	511.3 (8.6)   C	107.04 (16.89) B	9.09 (2.96) B	1.40 (0.20) B	16.87 (4.37) A
Materials with the same letter within a column are not significantly different (p>0.05).