الفهرس 
Resin CompositesOnly 14 pages are availabe for public view
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Abstract
This in-vitro study was carried out 10 investigate nanoleakage of three composite restorative systems (nanohybrid, bulk fill and flowable) with and without thermal and load cycling.Thirty intact, non-carious human premolars, extracted for orthodontic reasons were collected from patients aged (18-30) years old. All collected teeth were cleaned from blood, soft tissue and debris, washed thoroughly using distilled water and examined using 3 light microscope to ensure that there is no cracks or enamel defects. The teeth were stored in normal saline at 37°C in the incubator 2 months prior to testing.Root apices of all teeth were sealed with wax. For each tooth, the roots were inserted into self-curing resin mold, with the long axis perpendicular to the acr ylic resin hase. Standardized Class V saucer shaped cavit ies were prepared (3.0mm in depth, 2.0mm in width) above the cernento-enamel junction by 1mm, on the buccal surfaces of the teeth . The cavity depth and width were measured using a caliper. Cavities were prepared using carbide round burs in water-cooled and high-speed handpiece. No bevels were made at any of the enamel margins of the prepared cavities. Each bur was used for ten preparations and then replaced .After storage in disti lied water at 37°C for 24 h in the incubator, the prepared teeth were divided randomly into three equal groups (n= 10)according to the type of resin composite and the adhesive used:• group I: Were restored by Grandio@ SO Universal nano-h ybrid composite in incremental technique (two restorative increments each of 1.5mm which was cured for 10 sec. using blue phase n lvoclar vivadent light curing) with Futurabond ® M + Universal adhesive.