Tooth polishing This outermost fluoride rich layer of enamel is removed when tooth polishing is provided. The mineral components of saliva and polishing pastes containing fluoride can assist in remineralizing this outer layer. The enamel surface is strong enough to withstand repeated tooth polishing, but it should be avoided on newly erupted teeth, exposed root surfaces and areas of demineralization. If polishing does occur on these surfaces, fluoride therapy can minimize the risk of dental caries. Excessive pressure can lead to frictional heat that may cause pulpal discomfort or necrosis of the dental pulp. Surfaces of restorations may be damaged by conventional
S-layer pores with 2–8 nm in diameter. The terminology “S-layer” was used the first time in 1976. The general use was accepted at the "First International Workshop on Crystalline Bacterial Cell Surface Layers, Vienna (Austria)" in 1984, and in the year 1987 S-layers were defined at the European Molecular Biology Organization Workshop on “Crystalline Bacterial Cell Surface Layers”, Vienna as “Two-dimensional arrays of proteinaceous subunits forming surface layers on prokaryotic cells” (see "Preface", page VI in Sleytr "et al. 1988"). For a brief summary on the history of S-layer research see references For many bacteria, the S-layer represents the outermost interaction