الفهرس 
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Abstract
This study aimed to evaluate the bond strength of composite-composite repair using a condensable composite, a conventional flowable composite and a self adhesive flowable composite after different surface treatments. A total of 45 specimens were prepared and divided into 3 groups 15 each, according to the surface treatment used. The groups were subdivided into three subgroups five each according to type of repair material used. Disc shaped substrate specimens were prepared from condensable resin composite in a split Teflon mold. The specimens were aged in sodium chloride solution at 37ºC for one week. Three surface treatment protocols were adopted; Control group: no surface treatment, conditioning agent group with 37% phosphoric acid gel, conditioning + bonding agent group: 37% phosphoric acid gel and bonding agent. Five micro tubes were used to act as molds for repair composite and placed on the surface of the aged substrate disc. The tubes were cut and removed. All specimens were then aged after repair in sodium chloride solution at room temperature for 24 hours. Specimens were tested for microshear bond strength at a cross head speed of 0.5mm/min. The resulting fractured surfaces were evaluated under a scanning electron microscope. Results showed that the composite type significantly affected μ-shear bond strength. While it showed that the surface treatment had no significant effect on μ-shear bond strength. The adhesive failure was predominant in control groups, whereas all acid conditioned groups showed cohesive failure. In addition, the cohesive failure was also predominant in groups repaired with flowable resin composites. In conclusion, the performance of conventional flowable resin composite is the most reliable in repairing defective composite restorations, Self adhesive flowable composite can’t replace the conventional flowables for composite repair, and there is no direct relation between the microshear bond strength values and the failure modes.
Keyword:
Composite-Composite repair, self adhesive flowable composite, Microshear, Surface.