Efeito da largura temporal de pulso do Laser de Er:YAG em zircônia pré-sinterizada

Abstract

Silva BTF. Effect of Er:YAG laser pulse widths on pre-sintered zirconia [dissertation]. Sao Paulo: Universidade de Sao Paulo, Faculdade de Odontologia; 2015.Versao corrigida. This study evaluated the effects of different Er:YAG laser pulse width protocols on surface roughness, loss of volume of the material and the step height formed of presintered Yttrium-stabilized tetragonal Zirconia Polycrystal (Y-TZP) by threedimensional profilometric assessment. Blocks of pre-sintered Y-TZP were cut providing 63 standard 5mm thick samples which were divided by surface treatment, as follows (n=9): G1 (50μs); G2 (100μs); G3 (300μs); G4 (600μs); G5 (1000μs); G6 (tribochemical silica coating); G7 (Untreated). Laser settings: The Er:YAG laser (Fidelis III; Fotona, Ljubljana, Slovenia) 100mJ, 15,87J/cm, 10Hz, 1W, (60%) and air (40%) cooling. After treated or not, samples were sintered according to the manufacturer's recommendations. Roughness, volume loss and step and were analyzed by 3D profilometric assessment with confocal laser microscopy. Irradiated groups showed an increased roughness in the groups G1, G2, G3 and G4 when compared to G6 and G7 groups. The G5 group showed a completely flat and unfavorable surface for retention. The groups G1, G2 and G3 shown great loss of volume and the step height formed, which can lead to a gap on the crowns. In G4 were observed satisfactory roughness with little loss of volume and the step height formed similar to G6. Irrespective of laser protocol, any of the specimens showed presence of cracks and carbonization. It is suggested that the pulse width 600μs (G4) is the most suitable pulse width protocol as an alternative surface treatment, promoting micro-retention, with little loss of volume of material, comparable to gold standard treatment.