الفهرس 
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Abstract
This study was designed to evaluate the influence of immediate dentin sealing and delayed dentin sealing on the tensile bond strength and interfacial quality of two different indirect ceramic restoration with dentin.
Sixty recently extracted human molars were cleaned and stored in thymol solution. Teeth were randomly divided into two groups according to the ceramic restoration material, and then each of the two groups were subdivided into two subgroups according to dentin sealing protocol used (IDS, and DDS). DDS subgroup was further subdivided according to the curing protocol of adhesive.
A surveyor was used to ensure upright position of teeth in molds filled with self-cure acrylic resin.
The occlusal surface of each tooth was ground flat to expose the dentin surface using low speed diamond saw.
Sealing of occlusal surface using scotchbond universal adhesive was done either immediately after dentin exposure (IDS), or delayed after placement and removal of temporary filling (DDS)
Ceramic discs (6 x 3 mm) were fabricated from e.max and Vita Enamic blocks, and cemented to the exposed occlusal dentin surface after application of different sealing protocols according to the mentioned groups. For (DDS) group, the adhesive was either (pre-cured) before cement application or (co-cured) with cement after placement of the disc
Custom made stainless steel molds were fabricated and cemented to each specimen using cyanoacrylate adhesive to aid in the tensile testing.
Thermal cycling was performed and each specimen-mold complex was attached to the universal testing machine and tensile bond strength was measured.
The fractured specimens and fragments were collected and the mode of failure was examined visually and under stereomicroscope
The results showed that:
- Samples with immediate dentine sealing had a significantly higher tensile bond strength value than samples with delayed dentine sealing (p<0.001) in all tested groups.
- Pre-cured samples had a significantly higher tensile bond strength value than co-cured samples (p<0.001).
- Emax samples had a significantly higher tensile bond strength value than Vita Enamic samples (p<0.001) in all tested