الفهرس 
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Abstract
The present study evaluates the μTBS to CAD of universal adhesive with two different adhesive mode and the effect of CHX application. Twenty freshly extracted teeth with occlusal caries were used. The teeth were scaled cleaned and stored in chloramine solution until the time of specimens’ preparation. Each tooth was mounted in self-cure acrylic resin using plastic cylinders. Dentin was exposed by grinding the occlusal enamel with grinding disc under water-cooling until reaching the carious lesion surrounded by SD. A slow-speed diamond disc under water coolant was used to remove carious lesions. To obtain CAD, grinding was performed using combined criteria of visual examination and staining with caries detector dye. Teeth were randomly divided two main groups A, B according to the adhesive mode, 10 specimens each. Each main group was further subdivided into two subgroups. The four subgroups were Subgroup A1 representing ER mode without CHX pretreatment, Subgroup A2 representing ER mode with CHX pretreatment, Subgroup B1 representing SE mode without using CHX, and Subgroup B2 representing SE mode with CHX pretreatment. CHX and the universal adhesive for each subgroup was applied according to manufacturer instructions. After that, the composite resin build up was applied for the all tested samples. All specimens were subjected to artificial aging by storing them in dietary simulating solvents (citric acid solution) at room temperature for 3 months then thermocycled for 5000 cycles at 5o C and 55o C. Each tooth was sectioned longitudinally, perpendicular to interface with intervals of 1 mm using slow speed diamond disc under water coolant beginning from resin surface toward dentin reaching CEJ. Then the mounted tooth was rotated 90o and a new series of 1 mm sections were done, and then sectioned at its cervical to separate the microbars. Each microbar was attached to the set-up attachment by their sides, using cyanoacrylate glue, placed in universal testing then the tensile load was applied at cross-head speed of 0.5 mm/min until fracture of the specimen occurs and the maximum load at the time of failure was recorded. The fractured surfaces of the debonded samples were inspected under stereomicroscope at 40-x magnification to determine the mode of failure for each specimen. Statistical analysis was performed using Statistical Package for Social Sciences (IBM SPSS Statistics version 26). The results of the this study revealed that there was no significant difference between subgroup A1 (ER) and subgroup B1 (SE) in the μTBS of the tested adhesive which means that etching step with phosphoric acid is not necessary. Furthermore, CHX application did not decrease the μTBS when applied either in ER or SE mode.