Prior to surface treatment procedures, all ceramic blocks were immersed in distilled water and ultrasonically cleaned for 5 min (Cristófoli Equipamentos de Biossegurança LTDA, Campo Mourão, Brazil). The blocks were kept on a piece of gauze (~ 10 min) until complete water evaporation.
The HF was applied to the surfaces of groups as shown in Table 2. The area to receive the acid was delimited by an adhesive tape with a 3-mm perforation. HF (5 or 10%, FGM, Joinville, Brazil) was actively applied with a microbrush (Dentsply, New York, USA) for 20 or 60 seconds, washed with air / water spray for 30 seconds, and dried with a jet of air for 30 seconds. Afterwards, a layer of silane agent (Prosil, FGM; Joinville, Brazil) was applied to all samples with a microbrush (Dentsply, New York, USA) and left for 2 minutes for solvent evaporation according to the manufacturer's recommendations.
The HF was applied to the surfaces of groups as shown in Table 2. The area to receive the acid was delimited by an adhesive tape with a 3-mm perforation. HF (5 or 10%, FGM, Joinville, Brazil) was actively applied with a microbrush (Dentsply, New York, USA) for 20 or 60 seconds, washed with air / water spray for 30 seconds, and dried with a jet of air for 30 seconds. Afterwards, a layer of silane agent (Prosil, FGM; Joinville, Brazil) was applied to all samples with a microbrush (Dentsply, New York, USA) and left for 2 minutes for solvent evaporation according to the manufacturer's recommendations.