Raman micro-spectroscopy and bond-strength of simplified self and etch-and-rinse adhesives

Objectives: It was to evaluate the degree of conversion (DC) within hybrid layer in situ using Raman microspectroscopy and resin-dentin bond strength (µTBS) for etch-and-rinse and self etch systems adhesives. Materials and methods: twenty four caries free extracted third molars were divided into 4 groups, being 20 for µTBS (n=5) and 4 for DC, according to the Adhesive system use: Peak LC Bond used as self-etch [PBS] and etch-and-rinse [PBE] (Ultradent) [PB]; Clearfil SE Bond (Kuraray) [CSE]; Single Bond (3MESPE) [SB]). The occlusal enamel of all teeth was removed to expose a flat dentin surface, them the adhesives were applied according the manufacturer's directions. After the restoration with composite resin, specimens were stored in distilled water (24 h/37°C) before being perpendicularly cut with a low-speed diamond saw to obtain bonded resin-dentin beams with a cross-sectional area of 0.8 mm2. Two longitudinal sections were made in teeth for DC measurement to produce two 1–mm-thick slices per tooth for micro-Raman spectroscopy. The rest of the bonded sticks were tested in tensile stress at 0.5 mm/min. Data was submitted to a one factor ANOVA and Tukey's test (α=0.05). Results: The ANOVA results showed no significant difference between adhesives used regarding µTBS (p = 0.13) and DC (p = 0.26). Conclusions: All adhesive systems showed good results in terms of µTBS or DC. The new adhesive system Peak LC Bond can be used as self-etch and etch-and-rinse approach.