Abstract
One-bottle self-etching systems have recently been develop ed to reduce the number of clinical steps for resin application and have been widely used in dental clinical practice. The purpose of this s tudy was to evaluate the bonding abilities of five one-bottle adhesive resin systems (self-etching syst ems)using the microtensile bond test, fractography with a scanning electron microscope (SEM), and the silver-stained interfacial observation using a transmission electron microscope (TEM).
The bond strength was below 50 MPa for all the adhesive systems, indicatin g that there was no improvement in bond strength compared to traditional systems. SEM and TEM observations indica ted that the amount of nanoleakage formation was relatively small due to the combined structur e among the collagen fibers, dentinal hard tissue, and resin of the one-bottle resin systems. Severe nanole akage and water tree or bubble formation were however observed in the bonding resin layers because of their high content of water or solvents. It was thought that the reason for nanoleakage formation w as phase separation between resin monomer and water, or water sorption of resin from the dent inal tubles during bonding procedures. Since such nanoleakage will be a pathway of water invasion of the adhesive interfaces and result in reduction of long-term durability, a hydrophobic nature is requir ed for chemical formulation of bonding resin.
