Properties of New Partially Crystallized Lithium Disilicate CAD-CAM Materials

The purpose of this study was to compare the optical, mechanical, and biological properties of two new, inexpensive lithium disilicate (LS2) materials (Lodden (LOD), LD Medical Technology; and BeautyZir (BZ), BeautyZir Technology) to a clinically established LS2 material (IPS e.max CAD (EMAX), Ivoclar Vivadent).

The optical properties of the translucency parameter (TP) and opalescence parameter (OP) were obtained with a dental spectrophotometer. The mechanical properties of flexural strength (FS) and flexural modulus (FM) were determined through a three-point bend test conducted using a universal testing machine. Biocompatibility tests were conducted by analyzing cell proliferation using spectrophotometric absorbance (optical density) to determine relative growth rate and cytotoxicity. Representative specimens of the three LS2 materials were analyzed with X-ray diffraction to determine the relative crystalline phases. Data were analyzed with oneway ANOVA and Tukey's post hoc test (α=0.05).

Significant differences in optical and mechanical properties were found amongst the groups (p<0.05). Both LOD and BZ had significantly greater TP and OP compared to EMAX. EMAX and LOD had greater FS and FM than BZ. No significant differences in optical density or relative growth rate were found among any of the LS2 groups (p>0.05). EMAX and LOD had greater weight percent of lithium disilicate than BZ.

The new lithium disilicate LS2 material, LOD, exhibited better optical properties while maintaining mechanical and biological properties similar to the established LS2 material, EMAX.