الفهرس 
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Abstract
This study investigated the degree of conversion, shear bond strength and resin/dentin interface of three different adhesive systems (Single Bond 2, Easy One Bond and SE Bond) to dentin at three different time intervals: 24-hour, 6-month and 1-year using two different curing units (Halogen and LED).
Thirty specimens were prepared for the degree of conversion test using Potassium Bromide pellets according to the manufacturer’s instructions. The degree of conversion was done using FT-IR before and after light curing using the two different light curing units. Two-Way ANOVA was used to evaluate the effect of light curing units, adhesive systems and their interactions. Student t-Test was used to compare between the light curing units regardless to the adhesive systems. One-Way ANOVA followed by Tukey HSD test was used to compare between the different adhesive systems regardless to the light curing units. One-Way ANOVA followed by Tukey HSD test was used to compare between all experimental groups.
One hundred and forty four specimens were prepared for the shear bond strength test using the two curing units and the three adhesive systems according to the manufacturer’s instructions, and then the specimens were stored in tab water at room temperatures according to the different storage times. The shear bond strength test was regardless to the adhesive systems. One-Way ANOVA followed by Tukey HSD test was used to compare between the different adhesive systems regardless to the light curing units. One-Way ANOVA followed by Tukey HSD test was used to compare between all experimental groups.
One hundred and forty four specimens were prepared for the shear bond strength test using the two curing units and the three adhesive systems according to the manufacturer’s instructions, and then the specimens were stored in tab water at room temperatures according to the different storage times. The shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The maximum load applied to fracture the specimens was recorded and the shear bond strength in (MPa) was calculated. Three-Way ANOVA was used to evaluate the effect of light curing units, adhesive systems, storage times and their interactions. Student t-Test was used to compare between the light curing units regardless to the adhesive systems and storage times. One-Way ANOVA followed by Tukey HSD test was used to compare between the different adhesive systems regardless to the light curing units and between the storage times regardless to the light curing units and adhesive systems. One-Way ANOVA followed by Tukey HSD test was used to compare between all experimental groups.
A total of 36 specimens were prepared for the resin/dentin interface examination using the two curing units and the three adhesive systems according to the manufacturer’s instructions, and then the specimens were stored in tab water at room temperatures according to the different storage times. SEM was used to examine the interface at 500x and 1000x magnification respectively.
The results of the degree of conversion test showed no statistical significant difference between the light curing units or the adhesive systems or their interaction. Meanwhile for the results of the shear bond strength groups.
A total of 36 specimens were prepared for the resin/dentin interface examination using the two curing units and the three adhesive systems according to the manufacturer’s instructions, and then the specimens were stored in tab water at room temperatures according to the different storage times. SEM was used to examine the interface at 500x and 1000x magnification respectively.
The results of the degree of conversion test showed no statistical significant difference between the light curing units or the adhesive systems or their interaction. Meanwhile for the results of the shear bond strength showed a significant difference between the two curing units as well as between the adhesive systems. There was a significant difference between the 1-year storage period and the 24-hour storage period. There was no statistical significant difference between the 6-month and 24-hour storage period or between the 6-month and the 1-year storage periods. Single Bond specimens cured with Halogen and stored for 1-year showed the highest value among the whole specimens while SE Bond specimens cured with LED and stored for 24-hour showed the lowest values.
from the results of this study, several conclusions were suggested:
1- The light curing units and the adhesive systems used in the study had no direct effect on the degree of conversion.
2- The storage time had a positive direct effect on the shear bond strength.
3- There was a significant improvement in the shear bond strength of simplified etch-and-rinse adhesive system light cured with halogen curing units.
4- There was no correlation between the degree of conversion and the shear bond strength when two-step self-etch adhesives were used.