A Study on the Multipurpose Prime of Resin Modified Glass Ionomer Cement

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The purpose of this study examined the adhesive property for the bovine enamel and dentin of experimental multipurpose primer (GC Inc) developed for light-cured type II glass-ionomer cement (RMGIC).The mandibular incisors from 2-3 year old cattle stored frozen (-20 ℃) up to 2 weeks after extraction were used as a substitute for human teeth. Each tooth was then mounted in cold-curing acrylic resin (Tray Resin II, Shofu Inc) to expose die flattened area and placed into tap water to reduce the temperature rise from the exothermic polymerization of the acrylic. Final finish was accomplished by grinding on wet 600-grit SiC paper until a sufficient area of dentine was exposed.A material used in this study are Fuji Ionomaer Type II LC (GC Inc.) and 2 kinds of experimental primers. One of the primer was the phosphate system (PA) composed of 5wt% bis-methacryloxy ethyl phosphate, 35wt% 2-hydroxyethyl methacrylate (HEMA) 0.5% Camphorquinone (CQ) and 0.1 wt% reducing agent with 10wt% acetone solv … More ent. The other primer was carboxylate system (ME) composed of 5wt% 4-methacryloxyethyl trimellitate anhydride, 35wt% HEMA, 0.5wt% CQ and 0.1wt% reducing agent with 20wt% ethanol solvent. A Cavity Conditioner (GC Inc.) was used as a control. Bonded specimens were subjected to TC between 5℃-60℃ (the storage time in each bath was 1 minute) for 3,000, 10,000 and 30,000 times. The evaluation was carried out by measuring shear bond strength and fracture pattern after bond strength measurement and scanning electron microscopy (JSM-5400, JOEL) on bonded interface.The experimental multipurpose primers improved the enamel and dentin bond strength. The bond strength decreased with the increase in number of TC. Especially, the decreasing tendency of bond strength was different with the type of functional monomers in the experimental primers. It tended to retard the time in which the dentin bond strength decreased, when ME of the carboxylate system was used. A non-structure acid-resistant layer was observed in the bonded interface between Fuji Ionomaer Type II LC and tooth substrate, but the function of this layer for the contribution to bonding durability was unknoun. Less