ASSESSMENT OF PORCELAIN FUSED TO METAL BOND STRENGTH AFTER LASER SURFACE TREATMENT OF RECYCLED COBALT-CHROMIUM ALLOY

Recycling of casted alloys in dentistry is sometimes done to reduce price and minimizing environmental hazards. The current study assessed the use of laser surface treatment to enhance the shear bond strength between porcelain and Cobalt-Chromium alloy hindered by adding ratios of recasted alloy. Ninety disc-shaped samples were fabricated and assembled into six groups. Group A fabricated from fresh alloy without laser treatment (negative control), group B fresh alloy with surface treatment by laser (positive control), group C-75% fresh alloy mixed with 25% of once recasted alloy followed by laser treatment, group D-50% fresh alloy mixed with 50% of once recasted alloy followed by laser treatment, group E-75% fresh alloy mixed with 25% of twice recasted alloy and laser treated and group F-50% fresh alloy mixed with 50% of twice recasted alloy and laser treated. The results revealed non-significant values were calculated between group A (negative control group) and groups B, C, D, E and F with significance values (0.059, 0.612, 1.000, 0.922 and 0.845). Similarly, the difference between groups C, D, E and F showed non-significant values (0.479, 0.117 and 0.074). A significant difference at 0.05 level was seen between group B (positive control group) and group D, E and F with significance values (0.037, 0.003 and 0.002) respectively. Accordingly, laser surface treatment might be used as an effective surface treatment after adding recycled alloys to casting process in order to enhance bond strength with ceramic materials.