الفهرس 
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Abstract
The objective of this study was to evaluate microleakage and dentin shear bond strength of zirconia reinforced GIC compared to RMGIC in primary molars.
A total of twenty-eight primary molars were included in the study. Teeth were allocated randomly into four equal groups (n=7) according to evaluation method and type of applied glass ionomer.
For microleakage evaluation, fourteen sound primary molars were mounted in blocks of self-cure acrylic resin. A standardized class V cavity was prepared on the buccal surface of each molar in group I and groupII. In group I (test), Zirconomer Improved was applied. In group II (control), RMGIC was applied. In both groups, the specimens were thermocycled for 500 cycles, immersed into methylene blue solution for 24 hours, sectioned longitudinally and examined under a stereomicroscope at 40x magnification. In addition, microleakage was assessed quantitatively by measuring the percentage of dye penetration.
For SBS test, fourteen primary molars were mounted in molds of self-cure acrylic resin with the buccal surface facing upwards. The buccal surfaces of the crowns were gently mechanically ground to obtain flat dentin surface in group III and group IV. The GICs were applied in the two groups using cylindrical plastic mold with 3 mm diameter and 2 mm height. In group III (test), Zirconomer Improved was applied. In group IV (control), RMGIC was applied. Each specimen was mounted on the Universal Testing machine. SBS was assessed by measuring the force required to cause de-bonding. Then, each specimen was examined using a stereomicroscope to determine the pattern of the failure mode at x30 magnification.
The results of this study demonstrated that the difference in the median microleakage scores between the two groups was not statistically significant (p=0.06).
Regarding the results of the mean dye penetration percentage, group I (test) showed higher mean of dye penetration percentage than group II (control) with high significant difference at (P=0.01).
As for SBS test, the median SBS in the test group was significantly lower than the control group at (P=0.04).
For the mode of failure, the adhesive mode of failure was observed in 71.4% of the test specimens, while mixed failure was observed in 57.1% of the control specimens with no significant difference (P= 0.59).
According to the mentioned results, it was concluded that Zirconomer Improved retention is not as efficient as RMGIC.