Publication

Abstract : The surface microtexture and chemical changes induced in human enamel and dentin by processing with KrF excimer laser radiation were studied by SEM, XRD, XPS and FTIR. Processing at 1 J/cm² originates a relatively porous surface in enamel, due to preferential removal of the organic matter at the enamel prism sheaths. Increasing the fluence up to 10 J/cm² leads to a relatively flat surface presenting clear evidence of melting. For dentin, a cone-like topography develops in the fluence range 0.5-1 J/cm², provided that tubules are tilted within less than 35° to the beam direction. If the tubules are significantly tilted with respect to the laser beam, flat surfaces are achieved. For fluences in the range 2 to 10 J/cm², the treated surfaces are flat and covered with a layer of re-solidified material. Independently of the radiation fluence used, a significant reduction of the organic material content is observed in a surface layer a few nanometers thick in both enamel and dentin, but no significant changes in the mineral phase occur. Analysis of the properties and electronic structure of the enamel and dentin constituents allowed to identify the ablation mechanisms involved.