Purpose:To evaluate the effect of etching method and time on surface roughness and shear bond strength of universal adhesive to ground enamel.
Materials and Methods: Three etching agents, phosphoric acid (PPA), polyalkenoic acid (PLA) and phosphoric acid ester monomer (PPM) with one universal adhesive (G-Premio Bond) were used in the study. Fifty sound human molars were decoronated and sectioned mesiodistally to obtain 100  halves. Each half was fixed in self-cure acrylic resin. Ten specimens were selected as a control group (no etching) whereas, the remaining (n=90) was equally assigned into three tested groups (n=30) according to the etching agents. Every tested group was subdivided into three subgroups (n=10) according to the etching time (5, 10, 15 seconds). Tested groups were treated with acids and surface roughness was measured using a Profilometer. The universal adhesive was applied to all groups. Resin composite block (Tetric N-Ceram) was incrementally built up using a plastic mold. All the specimens were subjected to shear bond strength test.
Results: Surface roughness of enamel treated by PPA was the highest followed by PPM whereas, PLA showed the lowest value.Shear bond strength of universal adhesive to enamel etched with PPM and PPA for 5 to 15 seconds, and PLA for 15 seconds was significantly higher than other groups.
Conclusions:Enamel surface micro-morphology and bonding durability are etching protocol dependent. Enamel treatment withphosphoric acidincreases surface roughness more thanpolyalkenoic acid and phosphoric acid ester monomer. Polyalkenoic acid in 15 seconds enhances the enamel bonding.
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