The evaluation of fracture mechanics, microstructure and elemental composiotion of lithography sintered ceramic

Lithography based ceramic manufacturing (LCM) is an alternative technique to CAD/CAM technology in dental applications. This new technology has some advantages compared to conventional methods like reducing manufacturing time and cost, and enabling production of structures with high mechanical properties. The aim of this study was to compare the fracture mechanics, microstructure and elemental composition of LCM ceramic specimens with pressing and CAD/CAM methods. Disc-shaped specimens with 16 mm diameter and 1,2 mm thickness were used for mechanical testing in the present study (n= 10/group). The biaxial flexural strength of 3 groups (In-Ceram Alumina, Lithography based Alumina and ZirkonZahn) were determined using 'piston on 3 ball' technique as suggested in test Standard ISO 6872. Vickers hardness test was performed. Results were statistically analysed using one-way ANOVA followed by post-hoc Dunnett T3 test. Polished surface microstructure and fracture surface characterization were made with SEM. EDS was used for elemental analysis. The mean biaxial flexural strength of In-Ceram Alumina (ICA ) was 147,3 MPa, Lithography based Alumina (LCMA ) was 490,1 MPa, ZirkonZahn was 708,9 MPa respectively. Vickers hardness of ICA was 850 VHN, LCMA was 1581 VHN, ZirkonZahn was 1249 VHN. When the SEM images were examined, a homogeneous distribution was not observed in In-Ceram Alumina specimens whereas there was quite homogeneous microstructure in LCM Alumina and ZirkonZahn groups. EDS results were found to support the SEM images. Within the limitations of this study, it can be concluded that this new production method can be used successfully ceramic structure manufacturing under physiologic mastication loads. Key words: Dental ceramics, mechanical properties, LCM, layered manufacturing