الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This study aimed at achieving three goals. The first part of the present study was designed to evaluate and compare the shear bond strength and mode of failure of glass carbomer pit and fissure sealant and Helioseal-F pit and fissure sealant. A total of thirty extracted posterior teeth were randomly divided into two groups with fifteen teeth per group. The crown of each tooth was mounted in self cure acrylic resin inside cylindrical metal mold, the buccal surfaces of each specimen were ground flat then the sealant material was applied to the flattened buccal surface. Each specimen was mounted in Universal Testing Machine where shear bond strength was measured. Each specimen was then examined under a stereomicroscope at x18 and x25 magnification to determine the location and type of fracture. Glass carbomer pit and fissure sealant showed significantly higher shear bond strength than Helioseal-F pit and fissure sealant.
The second part of the study was designed to evaluate and compare the fluoride release of glass carbomer pit and fissure sealant and Helioseal-F pit and fissure sealant. A total of thirty disks were fabricated and randomly divided into two groups with fifteen specimens per group. Fluoride ions were measured with ion specific electrode. The fluoride release was evaluated after being stored in artificial saliva for 24 hours, 7 days, 14 days, 21 days and 30 days respectively.
Glass carbomer pit and fissure sealant showed the highest fluoride release after day 21 while Helioseal-F pit and fissure sealant showed the highest fluoride release after day 1. Glass carbomer pit and fissure sealant showed significantly higher fluoride release than Helioseal-F pit and fissure sealant.
The third part of the study was designed to evaluate and compare the fluoride uptake by enamel of glass carbomer pit and fissure sealant and Helioseal-F pit and fissure sealant. A total of thirty extracted posterior teeth were randomly divided into two groups with fifteen teeth per group. Each main group was further subdivided into 5 subgroups, 3 teeth per subgroup, according to the immersion period in artificial saliva into 24 hours, 7 days, 14 days, 21 days and 30 days respectively.