Etching and bonding
Group 1: The tooth surface was etched with 3M ESPE Scotch-bond Etchant (37% phosphoric acid gel) (3M ESPE, St. Paul, MN, USA) with an applicator brush for 15 s. The tooth surface was washed with a three-way syringe for 10 s and gently dried by blotting with a mini sponge to give a moist, glistening appearance, which ensured that the tooth structure was not overdried. Using an applicator brush, two even coats of etch-and-rinse dental adhesive (3M single bond 2 adhesive) (3M ESPE, St. Paul, MN, USA) were applied to enamel and dentin, gently agitated for 20 s to facilitate better penetration of the adhesive into the dentinal structure, followed by drying gently for a period of 2–5 s to evaporate the solvent and then light curing for 10 s.Group 2: Alkasite was bonded after selective etching of enamel. 3M ESPE Scotch-bond Etchant (37% phosphoric acid gel) (3M ESPE, St. Paul, MN, USA) was applied with an applicator brush only on the enamel for a period of 15 s. The tooth surface was then washed with a three-way syringe for 10 s and gently dried to give a moist, glistening appearance. Tetric N-Bond Universal (Ivoclar Vivadent Inc, New York, USA), a multimode dental adhesive, was applied to the surface of both enamel and dentin using an applicator brush, agitated for 20 s, dried with compressed air for 2 s to evaporate the solvent, followed by light curing for 10 s.