Effect of delayed composite placement over cured adhesive on the dentin shear bond strength of two universal adhesives: an in vitro comparative study

Background and objective. Unconsumed acidic monomers of universal adhesives have issues in the case when utilized with composite resin materials that contain tertiary amine as a co-initiator, which affects the bond quality to composite resin. The purpose of the presented work was to assess how 2 universal adhesives (G2-Bond universal and G-Premio bond universal; GC, Japan) performed in terms of dentin shear bond strength when composite placement had been delayed. Methods and materials. In accordance with adhesive systems (G-Premio bond universal and G2 bond universal), the mode of action (etch and rinse (E&R) and self-etch (SE), and the composite placement time (immediate and 5-minute delay), sixty-four extracted sound human maxillary premolar teeth have been divided into eight groups (n = 8). After utilizing a diamond cutting disk to cut the cusps, a flat dentin surface was achieved. For each one of the samples, G-aenial posterior composite has been put on dentin surface with the use of a specialized mold as well as cured either immediately or with a 5-minute delay following adhesives irradiation. Shear bond strength tests have been performed on all samples after they were kept in deionized distilled water for 24hrs. With the use of a dental microscope, the Mode of Failure has been examined in all samples. Results. Dentin shear bond strength for the two adhesives was significantly enhanced after five minutes of DCP (p less than 0.05). The bond strength of G2 bond universal has been much higher than that of G-premio bond universal (p less than 0.05). For the G2 bond universal and the G-premio bond universal, DCP performed better in E&R and SE modes, respectively. With DCP samples, the cohesive mode of failure was more evident. Conclusion. DCP for five minutes improved the shear bond strength of dentin over cured adhesives. Dentin composite bond strength was significantly increased by separate primer adhesive applications, especially when the etch and rinse method was used.