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Objectives:Fluoride release/recharge properties of fissure sealants are important for their long-term inhibition of caries. This study was conducted to examine the relationship between fluoride release and recharge of pit-and-fissure sealants.Methods:Specimens were prepared from 5 different sealant materials: Fissurit F, a conventional resin; Fuji VII, a glass-ionomer cement (GIC); Fuji II LC, a resin-modified GIC; Ionosit, a polyacid-modified composite resin (PMRC); and Aelite Flo, a flowable composite resin. Specimens stored in a polyethylene test tube containing 5.0 ml ultrapure water. On day 21, specimens were exposed to 1.23% APF gel. Fluoride release was measured using a fluoride-specific ion electrode at 1–7, 14, 21, 22, 28, 35 and 42 days.Results:The glass-ionomer based sealants Fuji VII and Fuji II LC had significantly higher fluoride release than the other materials at all times tested (P<.05). Fluoride release of all materials tested increased following exposure to APF gel (P<.05).Conclusions:Within the limitations of this short-term study, glass ionomer-based sealants were shown to have higher initial fluoride release as well as higher fluoride recharge capacity than other sealants.

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Compliance and strain energy release rate of homogeneous and interleaved end-notched flexure specimens for mode II fracture characterization are investigated with shear deformation beam theory and finite element analysis. Interleaving refers to a thin layer of polymer film being placed at the midplane of the beam. Analytical results are correlated with numerical finite element results for a wide range of interleaf thicknesses. The finite element results revealed that the compliance and energy release rate remained virtually the same whether the crack was within the interlayer or between the interlayer and the composite. Furthermore, within the accuracy of the numerical modeling, the asymmetric crack configuration did not render the specimen mixed mode, (G~ = 0). Close agreement was observed between sandwich beam theory and finite element analysis.

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