Comparison of depth of dentin etching and resin infiltration with single-step adhesive systems.

OBJECTIVES Adhesion of resin composites to dentin is currently believed to result from impregnation of adhesive resin into superficially demineralized dentin. The purpose of this study was to use micro-Raman spectroscopy and scanning electron microscopy (SEM) to investigate the extent of resin penetration into etched dentin with single-step adhesive systems. METHODS Adhesive systems used were One-Up Bond F (Tokuyama Dental) and Reactmer Bond (Shofu, Inc.). A self-etching primer system Mac Bond II (Tokuyama Dental) was employed as a control. Resin composites were bonded to bovine dentin with the adhesive systems, and specimens were sectioned parallel to dentinal tubules. Raman spectra were successively recorded along a line perpendicular to the dentin-adhesive interface in steps of 0.2 microm and the spectra were obtained. SEM observations of the resin-dentin interface were also conducted. RESULTS The dentin-resin interface of single-step adhesive systems showed a gradual transition in the relative amount of adhesive from the resin side to dentin side. The widths of resin penetration into demineralized dentin detected by Raman microscopy were greater than those obtained by the morphological analysis using SEM. CONCLUSIONS From the results of this study, a gradual variation in the composition of the dentin-resin interface was detected, and the degree of resin impregnation observed with SEM observation was less than that detected with the Raman microscopy.