Microtensile bond strength of glass ionomer cements to a resin composite using universal bonding agents with and without acid etching

To assess the effect of two universal bonding agents on the microtensile bond strength (μTBS) of encapsulated conventional glass ionomers (CGICs) and resin-modified glass ionomers (RMGICs) to a resin composite, with or without the use of 35% phosphoric acid. Four materials were used in this study: Riva Self-cure and Riva Light-cure; SDI and Equia Forte Fil and Fuji II LC; GC. The specimens were prepared in Teflon moulds with half the specimens for each GIC etched using 35% phosphoric acid (Ultra-Etch) and the remainder not etched. Each group was randomly subdivided into three groups, where the first two groups received an air-thin layer of bonding agent (G-Premio Bond = GPB or Clearfil Universal Bond = CUB) then light cured; and the third group had no bonding agent. For all groups, a nanohybrid composite (GC Kalore; GC) was placed incrementally on the GIC. Following 24 h immersion in distilled water, each block was embedded in epoxy resin in a cubic mould and sectioned by a cutting device. The stick specimens were then subjected to μTBS testing. The application of both universal bonding agents significantly enhanced the μTBS of all GICs (p < 0.001). Both RMGICs exhibited higher μTBS compared to that of CGICs (p < 0.001). The application of universal bonding agents with acid etching significantly increased the μTBS of both CGICs and RMGICs to resin composite in contrast to without acid etching. Using 35% phosphoric acid for 15 s prior to the application of universal bonding agents improved the μTBS of GIC to resin composite. Using Universal bonding agents with 15 s acid etching may increase the bond strength of both CGICs and RMGICs to resin composite when utilising the sandwich technique. Resin composite; Glass ionomer cements; Universal bonding agents; Microtensile bond strength; Acid etching.