Improving Flexural Strength of Dental Restorative Ceramics Using Laser Interference Direct Structuring

Zirconia and alumina ceramics restorative materials were treated with laser interference direct structuring using the third harmonic of a short pulse Nd:YAG and tested in a three-point bending test to measure the flexural strength. The surface was restructured in a periodic line-like pattern with controlled surface porosity and a surface composite pattern. As shown in earlier work [J. Am. Ceram. Soc. 91 [7] 2138-42 (2008), the composite consists of two different defect states rather than different phase compositions. The resulting mechanical properties are a function of the number of laser pulses, laser energy, and angle in between the laser beams defining the periodic feature distance [Adv. Eng. Mater., 9 [7] 823-26 (2005)]. The material's fracture strength could be controlled through the three mentioned laser parameters and in an initial study significantly improved by up to 50% from initial 422 to 630 MPa for alumina and 833 to 1250 MPa for zirconia.