الفهرس 
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Abstract
Several attempts in developing antibacterial GICs have been reported in the literature. The most appropriate choice of antibacterial agents to combine with GIC would be those providing the maximum antibacterial effect without disturbing its main physical and mechanical properties.
Accordingly; this study was conducted to assess five physical and mechanical properties (water sorption, solubility, fluoride release, surface micro-hardness and enamel shear bond strength) of two highly viscous glass ionomer cement formulations containing ethanolic extract of propolis at two different concentrations 25%, 50%, as antibacterial additives and comparing them with a control group of conventional HVGIC.
As for water sorption and solubility testing 15 cylindrical specimens were prepared based on the norms of the international organization for standardization (ISO), which requires the preparation of 5 disc specimens in each group ( n= 5 each group) for testing. Specimens were first desiccated until a constant mass was obtained. Specimens were immersed for 7 days in distilled water and immediately weighed after this period. Then the disks were post-desiccated and re-weighted daily till reaching a constant mass. Water sorption and solubility of each specimen were then calculated according to the change in its weight as observed before and after immersion and desiccation periods.
Regarding results: there was a statistically significant difference found between the three groups (p=0.0087) where group A showed the least water sorption. Water sorption of group A was significantly lower than both group B (p=0.012) and group C (p=0.012). group C showed higher water sorption than group B, however, there was no statistically significant difference between both groups (p=0.67). As for solubility there was no statistically significant difference between the three groups (p=0.147) with absence of any statistical correlation between water sorption and solubility levels. Propolis significantly increased water sorption of HVGICs.
As for fluoride release 36 cylindrical specimens were prepared; (n=12 in each of the three groups). Each specimen was separately immersed in a cylindrical tube with 10 ml deionized water. Readings were performed after 24 hours, 7 days and 28 days. The analysis of the amount of fluoride release was performed through water collected using the ion chromatography as previously described.
Results revealed that when comparing each pair of groups together, both groups B and C produced significantly higher fluoride release compared to the control group A at all time intervals. There was no statistically significant difference in fluoride release between group B and group C at all time intervals.
As for the surface microhardness 36 cylindrical specimens were prepared (n=12 in each of the three groups). Surface microhardness testing was carried out using a Vickers microhardness tester machine. The Knoop hardness test was performed using a diamond indenter with a 200-g load and 5-sec dwell time.
Results of surface microhardness showed a statistically significant diference between the three groups where group C showed significantly higher surface microhardness compared to group B (p=0.025) and group A (p=0.0002). group B showed significantly higher surface microhardness than group A (p=0.004).
Shear bond strength test (SBS) involved 36 primary prepared enamel specimens. Primary molar specimens were randomly and equally divided into 3 groups according to the materials used (n = 12 each group). SBS was then evaluated using a Universal Testing Machine at a crosshead speed of 0.5mm/min.
As for the results; there was a statistically significant difference found in the enamel shear bond strength between the three groups. (p=0.002), where group A showed higher SBS than group B followed by group C.