Y-TZP, yttria-stabilized tetragonal zirconia polycrystalline; Al 2 O 3 , aluminum oxide; MDP, phosphate ester monomer 10-methacryloyloxydecyl dihydrogen phosphate. Standardization of the cementing surface All zirconia cylinders had their surface planed and polished with 320, 600, and 1200 grit wet sandpaper in a metallographic polisher for 10s for each grit. Then, the cylinders were cleaned in an ultrasonic vat with 92.8INPM ethanol for 10min. After cleaning, they were blotted dry for 1min and then blown with dry, oil-free air for 10s.