Influence of Storage and Handling Conditions of Bonding Agent on the Bond Strength to Enamel

Abstract

This study examined the influence of storage and handling conditions of bonding agent on the enamel bond strength. Bonding systems used in this study included two kinds of one-step type (GB and AB), one kind of two-step(self-etching-primer+adhesive)type(MB), and one kind of three-step type (MP). Bovine enamel and flowable resin composite were used as the adhered materials. The bonding agents were stored at room temperature (23℃) or at refrigerated temperature (4℃). The bonding agents were removed from the refrigerator at 4℃ and allowed to reach 23℃ 8 hours before use (4℃⇔23℃). The storage period was 1, 30, 60, 90 and 180 days. In the case of the one-step type, an experiment was additionally performed in which the bonding procedure was made at 0, 1, and 2 minutes after dish sampling. The bonded specimens were subjected to a shear bond strength test after 24-hour immersion in distilled water. The results obtained were as follows: 1. For the GB and MB stored at 23℃, the bond strength decreased significantly when preserved for 90 and 180 days as compared with 1 and 30 days. 2. For the AB and MP stored at 23℃, the bond strength decreased significantly when preserved for 90 and 180 days as compared with 1, 30 and 60 days. 3. For the GB, MB and MP stored at 4℃ and 4℃⇔23℃, the bond strength decreased significantly when preserved for 180 days as compared with 1 day. 4. For the AB stored at 4℃ and 4℃⇔23℃, the bond strength decreased significantly when preserved for 90 and 180 days as compared with 1 day. 5. No significant difference was observed in the bond strength of the one-step type determined at 0, 1, and 2 minutes of the procedure after dish sampling irrespective of the storage conditions.