SEM comparison of acid-etched, CO2 laser-irradiated, and combined treatment on dentin surfaces

Research into polymer systems capable of bonding to dentin and enamel have resulted in improved bond strengths that allow more conservative restoration and strengthening of teeth. However, pretreatment of the dentin and enamel of various sorts, including exposure to laser energy, have been espoused to enhance this bonding. This study investigated the effects of two pretreatments, acid and CO2 laser exposure, both alone and in combination, on the surface topography of prepared dentin specimens as observed by scanning electron microscopy. Eighteen dentin specimens were flat-sanded with 600 grit sandpaper and exposed to 10% maleic acid and CO2 laser both alone and in combination. SEM observation suggested that laser treatment prior to acid etching could increase the resistance of the smear layer to acid removal, that laser exposure after acid treatment could expose a porous topography suggestive of the underlying dentin inorganic structure by way of vaporization of the collagen surface left after acid demineralization, and that these effects varied in degree with the laser exposure energy.