الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 115 |  |  |
| | | from | 115 | | |
Abstract
Our study aimed to investigate the effect of adding EGCG in two different concentrations 100µg/ml 200µg/ml on the color stability,
water sorption and bond strength of an etch and rinse dental adhesive to dentin.
According to literature Matrix metalloproteinases became active after acid etching the dentin, they degrade the collagen fibers which affects the bond strength to dentin and the durability of the resin dentin bond. EGCG is the main flavonoid of green tea and is known to preserve the bond strength to dentin by acting as collagen cross linker and MMps inhibitor.
EGCG was applied to the adhesive in two different concentrations forming EGCG/adhesive mix with concentration of 100µg/ml and 200µg/ml.
Color stability testing of EGCG/adhesive mix in both concentrations and the control group was done by applying an adhesive layer to IPS emax discs.
The color of each disc was measured using Agilent Cary 5000 spectrophotometer (Santa Clara, California, United States) before applying the adhesive, 24 hours, 6 month and 1 year after applying it. During this period the discs were stored in distilled water.
Water sorption and solubility testing of EGCG/adhesive mix in both concentrations and the control group was done by weighing the samples before and after being placed in distilled water for 7 days following the 4049 ISO standards.
Infrared spectroscopy of the distilled water before and after removing the discs from it was done using Vertex 70 FTIR spectrometer (Burker, Germany)
Microtensile bond strength testing of the two concentrations of EGCG in the adhesive was done using universal testing machine (Instron, MA, USA) and compared to the control group. Load applied was 500 N at cross head speed of 0.5 mm/min, until debonding of the specimen occurred. Bond strength was calculated by Bluehill lite software and mode of failure was detected by scanning electron microscope.
83
Summary and conclusions
Specimen storage for one year was done to test the effect of EGCG on the durability of resin dentin bond.
For the color stability testing adding EGCG did not affect the color stability of the adhesive
Results for the water sorption and solubility testing showed that EGCG increased the water sorption of the adhesive and decreased its solubility
The results of the micro-tensile bond strength test showed a significant increase in the bond strength after EGCG application in the concentration of 100µg/ml after 24 hours. After aging there was a significant decrease in bond strength of the control group after 6 months. On the other hand, for the EGCG/ adhesive mix with concentration of 100µg/ml there was a significant decrease in bond strength only after 1 year. Regarding the EGCG/adhesive mix of concentration 200µg/ml there was a significant increase in bond strength after 6 months. Adding EGCG to the adhesive was able to preserve the bond strength of the adhesive after water storage
Finally, within the limitations of the present study , we can conclude that incorporation of EGCG into the adhesive improved its bond strength to dentin, solubility and color stability.