Table 1 Groups and surface treatments

Group C

Control group, specimens which were untreated.

Group S

Specimens were sandblasted with 50-μm Al₂O₃ powder (Korox 50, Bego, Germany) at 2.8 bar for 15 s through a nozzle distance of 10 mm.

Group 3 W

CO₂ laser: the applied energy level was 382w/cal 3 W.

Group 4 W

CO₂ laser: the applied energy level was 509w/cal 4 W.

Group 150SP

Er:YAG laser: the applied energy level was 150 mJ with 10-Hz frequency for 45 s. The pulse width 100 μS.

Group 150SSP

Er:YAG laser: the applied energy level was 150 mJ with 10-Hz frequency for 45 s. The pulse width 300 μS.

Group 300SP

Er:YAG laser: the applied energy level was 150 mJ with 10-Hz frequency for 45 s. The pulse width 300 μS.

Group 300SSP

Er:YAG laser: the applied energy level was 300 mJ with 10-Hz frequency for 45 s. The pulse width 300 μS.