الفهرس 
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Abstract
a
Repair bond strength differs from different surface treatment protocols with different hybrid ceramic materials
The present study showed the effect of four different surface treatment protocols of the repair surface of two hybrid ceramic material (crystal ultra and cerasmart)
Materials and methods: specimens were divided into two groups according to the hybrid ceramic material and then were further divided into four subgroups according to the surface treatment protocol.The specimens were cut with thickness 1 mm each urysing isomet 4000 then were fixed in acrylic resin blocks which were color coded ;green for cerasmart and pink for crystal ultra.standardization of the repair surface was done by polishing with wet silicone carbide paper 1000 grit followed by ultrasonic cleaning for 3 minutes in distilled water and then aged in distilled water for 24 hours at 37 °C.
The surface treatment protocols were applied ;CO: no surface treatment ,CJ:cojet sandblasting with pressure 2.8 bar at 5 mm distance for 10 seconds,HFS:9% hydrofluoric etching for 1 minute,37% phosphoric etching for 30 seconds for both groups CJ and HFS, MBEP:selfetch ceramic primer (monobond etch and prime).Attaching cylinders of iris cuts of 1 mm height and internal diameter of total 120 cylinder ;15 cylinder in each surface treatment protocol of each hybrid ceramic material then nanohybrid flowable composite(polofil NHT Flow composite resin) was injected in the lumen .
Thermocycling for 5000 cycles between 5°C and 55°C with a 20 seconds a dwell time and 5 seconds a transfer time for the specimens before microshear testing with a cross-head speed of 0.5 mm/min.The specimens were evaluated with SEM 1000x after the surface treatments and the mode of failure as well with SEM 100x after the microshear test.
Results showed that, microshear bond strength is higher in crystal ultra samples treated with monobond etch and prime.Within Cerasmart, samples treated with (Cojet& silane) had the highest microshear bond strength followed by samples treated with (HF acid & silane), (Monobond) and finally samples that did not receive any surface treatment. Within Crystal ultra, samples treated with (Cojet& silane) had the highest microshear bond strength followed by samples treated with (Monobond), (HF acid & silane) and finally samples that did not receive any surface treatment.