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"nBackground and Aim: Pit and fissure sealant therapy, is one of the most effective methods, in prevention of occlusal caries. Saliva contamination before curing the resin can increase the risk of failure in this method. The purpose of this study was to evaluate the effect of saliva contamination prior to curing on microleakage of pit and fissure sealants. "nMaterials and Methods: In this experimental in vitro study 21 sound human pre molars were selected and two standardized V-Shaped fissures were prepared on both buccal and lingual surfaces, then they were randomly divided into two equal groups. In the control group, the sealant was cured without any saliva contamination and in the case group, the sealed teeth were immersed in artificial saliva for ten seconds before curing. After thermocycling the samples were immersed in 2% fouchsin solution for 24 hours and then sectioned longitudinally in bucco - lingual direction. The specimens were then fixed and assessed under stereomicroscope to determine microleakage and dye penetration using paired student t. test. P

The purpose of this study was to assess the fluoride release of three fluoride- containing materials exposed to fluoride solutions. This study compared the initial fluoride release and release following re-fluoridation (neutral or acidic 2% NaF) of three different filling materials, conventional glass ionomer cement (CG1C), resin- modified glass ionomer cement (RMGIC), polyacid- modified composite resin (PAMCR). Twenty discs of each material, measuring 2mm height and 6mm diameter, were suspended in separate vials of 2" laboratory artificial saliva. The amount of fluoride release was measured over two periods of 28 days each. Fluoride release was determined at 1,3,7,14 and 28 days of each period. Fluoride was measured with a fluoride ion- specific electrode and an ion analyzer previously calibrated with standard solution .T- test and ANOVA were used to evaluate the data. Fluoride release for all products at days 1 and 3 was significantly greater than the rest of the time intervals. Then, the fluoride release decreased significantly. CGIC released significantly more fluoride than the other products. This was followed by RMGIC, which exhibited significantly more fluoride release than PAMCR. In second period of experiment, the specimens were assigned to two subgroups often each. The samples exposed to two different solution of NaF (neutral or acidic). All groups showed the capacity of re-fluoridation and fluoride uptake. The specimens exposed to acidic NaF solution showed statistically more significant rechargeability than the neutral NaF solution. It may be concluded that glass ionomer cements act as a rechargeable slow fluoride release systems and as an effective caries preventive material in caries preventing programs for caries susceptible children.