EFFECT OF LASER AND CHEMICAL SURFACE TREATMENT OF COBALT-CHROMIUM ALLOY ON ITS BOND STRENGTH WITH HEAT CURED ACRYLIC RESIN (COMPARATIVE LABORATORY STUDY)

Abstract

INTRODUCTION: Durability of the removable prostheses is dependent on strong adhesion between the metal framework and acrylic resin. Weak adhesion causes separation of the denture base from the metal framework. It was reported that Neodynium-doped yttrium aluminium garnet (Nd:YAG) laser surface treatment can be used to strengthen the bond between dental alloys and resins. Aryldiazonium salts have been used to create a strong chemical bond between dental alloys and polymers. OBJECTIVES: To evaluate and compare the effect of Nd:YAG laser surface treatment and Aryldiazonium salts of cobalt chromium (Co-Cr) alloy on its bond strength with heat cured acrylic resin. Also, to analyze the metal-resin interface at a high-resolution level after laser and Aryldiazonium salts surface treatments. MATERIALS AND METHODS: Ten healthy adult white Albino New Zealand rabbits, after creating two osseous defects in the right femur in each. The defects (upper and lower) were divided in to two groups according to the material used for filling: Group A (Control): in the upper defect, bone graft only was added in the lateral side of the right femur. Group B (Study): in the lower defect, MPM was added in the lateral side of the right femur. After 2 &8 weeks respectively postoperatively, sacrification of the rabbits was done. RESULTS: Data collected from histological results revealed that MPM enhanced bone formation where increased amount of new bone formation was observed in the study group in relation to the control group. At the end of the experimental period, the defect area was almost filled with mature bone which occupied a greater surface area in the study group. Histomorphometric analysis revealed that there was increase in the mean percentage of bone surface area in the study group in comparison to the control group. This increase was statistically significant in the 8 weeks period. CONCLUSIONS: The bond strength between heat cured acrylic resin and alloy can be increased by Aryldiazonium salts application and laser surface treatment