Imaging of Dental Hard Tissue Surfaces Prepared by an Ultrashort Pulsed Laser System (USPL)

Abstract The aim of this study was to compare surface structures of laser-irradiated dental hard tissues using confocal (CFM), atomic force (AFM), and scanning electron microscopy (SEM). The general potential of the AFM in analyzing laser-irradiated surfaces was determined in this context. Specimens of human enamel and dentin were irradiated using an 8.6 W Nd:YVO₄laser with a pulse duration of 8 ps,λ_Center=1,064 nm, and a pulse repetition rate of 500 kHz. Surface topology of irradiated areas (1 mm²) was investigated using AFM, CFM, and SEM. Surface roughnessR_zwas measured only with the AFM and the CFM. For non-irradiated enamel and dentin surfaces, roughnesses for CFM and AFM are in the nanometer range. However, major differences in roughness were determined for laser-prepared surfaces. For enamel,R_z(CFM)=2.33μm is much higher compared withR_z(AFM)=0.09μm; in the case of dentin,R_z(CFM)=5.35μm is also much higher compared withR_z(AFM)=0.093μm. Information regarding structural properties of surfaces needs real dimensions, particularly for use in dentistry. In this respect, AFM technology provides no additional results that lead to a significant improvement.