Abstract
Aqueous bonding agents were developed to make the adhesion between composite resin and dentin retaining its smear layer without any etchings and primings in order to simplify the clinical operations.The water-soluble photo polymerization initiator, 2-hydroxy-3-(3, 4-dimethyl-9-oxo-9H-thoixanthen-2-yloxy)-N, N, N-trimethyl-1-propanaminium chloride(QTX), was used at a concentration of 2% with 0.3% N-phenylglycine(NPG).The bonding agent was applied onto the polished bovine dentin surface.After drying, the bonding agent was polymerized by photo-irradiation.The low viscosity composite resin was applied as a thin film and then the composite was filled, and was respectively polymerized by photo-irradiation.The tensile bond strength was measured after the immersion in 37℃ water for 24hr.The adhesive durability was determined by measurement of the bond strength after thermal cycling between 4 and 60℃ in a water bath.The bond strength by the scrubbing method was also measured as above mentioned.The NPG agent gave the mean bond strength of about 10MPa after a 60 sec application and 30 sec irradiation.Although the mean bond strength with a 15-sec application was only about 4MPa, the bond strength with a 15-sec scrubbing was about 8MPa.The remaining smear layer and dentinal plug were observed by SEM after the application and scrubbing of NPG agent.The 15 sec scrubbing of NPG agent showed no decrease in the bond strength after 2, 000 thermal cycles.
