Three-dimensional profilometric assessment of Er:YAG laser irradiated unsintered zirconia

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 pre-sintered yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) by three-dimensional profilometric assessment. Blocks of pre-sintered Y-TZP were cut providing 63 standard 5-mm-thick samples which were divided by surface treatment, as follows (n = 9): G50 (100 mJ/10 Hz/1 W-50 μs); G100 (−100 μs); G300 (−300 μs); G600 (−600 μs); G1000 (−1000 μs); GTC (tribochemical silica coating); and GNC (untreated). After treated or not, samples were sintered according to the manufacturer’s recommendations. Roughness, volume loss and step height were analyzed by 3D profilometric assessment with confocal laser microscopy. ANOVA and Tukey’s test (p < 0.05) detected that irradiated groups showed increased roughness in the groups G50, G100, G300, and G600 when compared to GTC and GNC groups. The G1000 group showed a completely flat and unfavorable surface for retention. The groups G50, G100, and G300 showed great loss of volume and the step height formed, which can lead to a gap on the crowns. In G600 was observed satisfactory roughness with little loss of volume and the step height formed similar to GTC. Irrespective of laser protocol, any of the specimens showed the presence of cracks. It is suggested that the pulse width 600 μs (G600) is the most suitable pulse width protocol as an alternative surface treatment, promoting micro-retention, with little loss of volume of material, comparable to silica coating treatment.