ABSTRACT
The shear bond strength between composite and dentine after using adhesive of different modes of actions was evaluated in this study. Freshly extracted sound human molars were selected, embedded in steel rings using improved dental stone. The buccal surfaces of 180 specimen were cut to expose dentine using a milling machine. The denuded dentine surface were either untreated or treated by EDTA or ferric oxalate. Two different adhesive systems bonding either to the organic or inorganic portions of dentine were used. A combination of both the organic and inorganic dentine adhesive was also used. A light cured composite resin was placed on the treated dentine surface by a teflon ring. The specimen were divided into nine equal groups and tested for shear bond strength using a universal testing machine. The results revealed that the highest mean shear bond strength scores were obtained with the use of the combination of dentine adhesive followed by the adhesive bonding to the organic component of dentine. Furthermore, the use of EDTA for the surface treatment of dentine was found to greatly improve the shear bond strength values of the dentine bonding agents to dentine surface