Surface conditioning of artificial caries lesions with Er, Cr:YSGG laser before resin infiltration: an in vitro study

The aim of this study was to evaluate the ability of different pretreatments to remove the surface layer of artificial enamel caries lesions in vitro in preparation for resin infiltration.

Eighty-eight bovine enamel samples (5 × 5 × 4 mm³) were demineralized for 21 days to create artificial lesions. Samples were then randomly divided into four groups based on the pretreatment methods (n = 22). Lesions were etched with 35% phosphoric acid (H₃PO₄) or 15% hydrochloric acid (HCl) for 5 s. The two laser groups included the irradiation of the enamel surface using Er,Cr:YSGG laser (2,780 nm wavelength, 140 m pulse duration, 80% water, 60% air) with glass tip (MZ8), focused mode at 3.5 W/100 Hz and 4 W/100 Hz. Two samples from each group were selected to determine the morphology of the enamel surfaces with the SEM (n = 2). Rest of all lesions were infiltrated for 10 s (n = 20). The confocal laser scanning microscope was used to examine the samples. Lesion depths (LD), the erosion depths of the surface layer (ED) and penetration depths of the infiltrant (PD) were measured. The percentage of penetration (PP) was calculated.

In comparison to H₃PO₄, the infiltrant’s PP was significantly higher after using HCl or a laser (p < 0.05 Mann-Whitney test). Respecting ED and PD the laser groups produced similar etching patterns to conventional methods (p > 0.05).

The pretreatment with an Er,Cr:YSGG laser results in a deeper erosion of the surface of artificial enamel lesions when compared to H₃PO₄ and a similar erosion when compared to HCl.