Role of Laser Etching on Shear Bond Strength between Recast Nickel-Chromium Alloy and Dental Ceramic: An Experimental Study.

The purpose of this study was to investigate the effect of laser etching, air bone particle abrasion and acid etching on shear bond strength between re-cast Nickel Chromium alloy and dental ceramics. A master die was made according to ISO 9693; TR (11406). A total of 40 samples were fabricated with 50%w nickel-chromium alloy and 50%w previously casted nickel-chromium alloy. The samples were divided into four groups based on the surface treatment applied. Group 1 served as the untreated control, Group 2 underwent etching with 10% hydrochloric acid (HCl), Group 3 received surface treatment via air-borne particle abrasion, while Group 4 was conditioned using a pulsed Nd:YAG laser. Shear bond strength between ceramic and metal was tested using a universal testing machine and the mode of debonding was evaluated using scanning electron microscope. The obtained values were statistically analyzed using one-way ANOVA and Tukey's HSD Post Hoc test. The mean values of shear bond strength for Group 1 was 22.69±2.63Mpa, Group 2 was 27.05±2.15Mpa, Group 3 was 34.46±2.46Mpa and Group 4 was 39.54±2.16Mpa. The difference among the groups was significant (P<0.001). Hence there was a statistical difference seen in shear bond strength between control and acid etching, air borne particle abrasion and laser etching. Laser surface conditioning produced more surface roughness compared to acid etching and air bone particle abrasion on re-cast Nickel Chromium alloy which increased the shear bond strength markedly between recast nickel-chromium alloy and dental Ceramic.