Flexural Strength and Fracture Toughness of various Core Build-up Materials

To evaluate (i) the flexural strength and (ii) fracture toughness of various commercial core build up materials.

Methods:

Four materials were inve:stigated: Core.X flow, SmartCem2, Bright flow core, and Fuji II LC. The flexural strength was determined by using uniaxial three-point bending test (25 mm x 2 mm x 2 mm). The single edged notched method was used to evaluate the fracture toughness of the tested materials (3 x 6 x 34 mm). Specimens (n=20) of flexural strength and fracture toughness were tested after being incubated for 24hr (dry) at 37 ºC, and at cross head speeds of 0.5mm/min and 0.125mm/min respectively, using a Universal Testing Machine (Zwick/Roell Z020, Leominster,UK) Data were analysed with the use of one-way analysis of variance (ANOVA) followed by the Tukey post-hoc test (P<0.01).

 Results:

Mean Flexural strength (SD) ranged from 94.9 (3.4) for Core.X flow, to 51.6 (7.1) MPa for Fuji ll LC. Mean Fracture toughness (SD) ranged from 2.03 (0.11) for Core.X flow to 1.02 (0.19) MNm^-1.5 for Fuji II LC. All values and statistical significance are shown in the Table below where same superscript letters indicate no significance within the same column. 

Conclusions:

All tested materials showed an acceptable in vitro performance as core-build-up materials. Core.X flow had the highest values for both tested properties