Effect of experimental adhesives on microleakage of Class V restorations

objectives: The aim of the present study was to investigate the microleakage of dentin-bordered composite restorations using new experimental self-etch and total-etch adhesive systems. Methods: Standardized Class V cavities (3x3x1.5mm) were prepared on non-carious human first premolars on the facial or lingual surface of each tooth with coronal margins in enamel and apical margins in cementum at the cemento-enamel junction (CEJ). A series of self-etch, respectively total-etch adhesive systems based on a new experimental urethane dimethacrylic acidic monomer with and without 10wt% hydroxyapatite were applied accordingly to the manufacturer instructions. The preparations were restored using a series of new experimental microfilled hybrid resin composites based on Bis-GMA0-2 superior oligomers, a hydrophobic Bis-GMA analogue containing urethanic groups, TEGDMA and HEMA in different ratios and inorganic filler consisted of 90% silanized barium glass and 10% silanized colloidal silica. A control group without the adhesives was used. The specimens (restored teeth) were thermocycled 1,000 cycles, immersed in 1% methylene blue dye for 24 hours and invested in acrylic resin. The specimen blocks were then sectioned longitudinally and the most infiltrated section of each tooth was selected under magnification, scanned, and quantitatively analyzed using a computer program. Coronal and apical margins were scored separately for microleakage using a 0-3 ordinal ranking system. Data were analyzed using Krushall/Wallis and Man/Whitney tests. Results: The comparison of the adhesives containing preparations group with the control group at the coronal and apical margins revealed significant (p < 0.0001) differences. The extent of microleakage depended mainly on the composition of the adhesive system, the composition of the resin composite having a smaller influence. Conclusion: The results suggest that the application of a conventional two-bottle bonding system used with a "total etch" technique is better than that of a self-etching adhesive system.