In summary, it can be stated that, although the erbium laser wavelengths apparently have the potential to increase acid resistance, their application solely for caries prevention would not appear to be sensible under the prevailing conditions.

The swelling of PVF and PVDF films in various solvents was investigated. It was found that in the swollen state both polymers show little tendency to retain the solvent that leaks out under a mild pressure and evaporates quickly when the specimen is exposed to air. The equilibrium swelling ratios were measured in numerous solvents. From the results it is concluded that the solubility parameters are δPVDF = 12.0–12.3, δPVF = 12.0–12.1. The unusual swelling behavior is explained by strong polymer–polymer interactions via dipoles which tend to replace polymer–solvent interactions once the sample is withdrawn from the solvent.

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