Deflection of cast titanium induced by laser surface treatment

Objectives: To investigate the effect of voltage, spot diameter and treatment method on the deflection of cast titanium plates surface-treated by Nd:YAG laser. Methods: Cast titanium plates (3.0 x 20.0 x 0.5mm) were prepared using the Ticast titanium casting system. After the cast plates were air-abraded with 50mm alumina, one side of plates were laser-treated by a dental laser unit (Neolaser L, Girrbach) at voltages of 150V and 200V and spot-diameters of 1.0mm and 1.5mm. Laser treatment underwent two different (50% overlapped and non-overlapped) methods to the entire surface of each plate. Deflection was measured as the height (mm) of curves when the plates were seated on a flat plane. Deflection data (n=5) were analyzed by 3-way ANOVA. Results: Statistical analysis demonstrated significances for each factor; Voltage (p=.000, F=186.4), Spot-diameter (p=.000, F=39.4) and treatment method (p=.003, F=10.6). Decreasing the spot-diameter (1.5mm > 1.0mm) and the number of laser spots (Overlap > Non-overlap) decreased the value of deflection for each voltage. Increasing the voltage also decreased the deflection values (150V > 200V) for each spot-diameter and treatment method. Conclusion: The results of this study suggested that the higher voltage and smaller spot-diameter to concentrate laser energy could minimize the deflection of surface-treated cast titanium. Supported in part by the Baylor Oral Health Foundation.