A preparation for the care and hygiene of the mouth contains, as an active ingredient, between 5 and 15 per cent by weight of a higher aliphatic acyl amide e.g. a fatty acyl amide, of an amino carboxylic acid e.g. lower aliphatic amino monocarboxylic acid, and does not contain fatty acids or materials, or soaps, in amount sufficient to reduce or neutralize its ability to inhibit acid production from carbohydrates by bacteria and to be adsorbed on proteinaceous material i.e. less than 15 per cent by weight of the amide.  The terms "higher" and "lower" are defined as meaning from 12 to 16 carbon atoms and up to 6 carbon atoms respectively.  The amide may be a condensation product of a higher fatty acylating compound and an amino acid compound, and may be of formula <FORM:0753979/VI/1> where R-CO is a saturated fatty acyl radical of from 12 to 16 carbon atoms, R1 is a hydrogen atom or an alkyl group of up to 4 carbon atoms, and X is a hydrogen atom or a cation which forms non-toxic, water-soluble salts.  The preparation may also contain a calcium or magnesium ion suppression agent in an amount not exceeding 5 per cent by weight of the preparation which may be a water-soluble inorganic sequestering agent such as an alkali metal phosphate, or an organic chelating agent such as an alkali metal salt of ethylene diamine tetracetic acid or citric acid. The preparation which may take the form of a mouth wash or a tooth cleansing preparation e.g. dental cream, tooth powder, liquid dentifrice, chewing gum, may contain a gelling agent and/or a water-insoluble dental polishing agent which may contain calcium or magnesium or both and may be, at least in part, a water-insoluble phosphate.  Suitable amides may be derived from glycine, sarcosine, alanine, 3-aminopropanoic acid and valine. The preferred salts are those of the alkali metals, ammonium, amine, alkylolamine such as sodium and potassium N-lauroyl sarcoside, sodium N-myristoyl sarcoside, sodium N-palmitoyl sarcoside, sodium N-lauroyl glycide, N-lauroyl sarcosine. Abrasives which may be used are calcium carbonate, dicalcium phosphate, tricalcium phosphate, aluminium hydroxide, sodium metaphosphate, magnesium hydroxide, magnesium carbonate, bentonite.  Gelling agents which are disclosed are Irish moss, gum tragacanth, sodium alginate, gum karaya, pectin, starch, glycerites, and sodium carboxymethylcellulose.  Suitable ion suppression agents are tetrasodium pyrophosphate, sodium tripolyphosphate, disodium diacid pyrophosphate, hexasodium tetraphosphate, sodium hexamethaphosphate, alkali metal salts of ortho and metaphosphoric acids.  Stabilisers are sodium citrate, di-, tri- or tetrasodium ethylene diamine tetraacetate, sodium gluconate. Chewing materials used are chicle, jelutong, pontianak, gutta kation, gutta soh., rubber latex, polyvinyl acetate, butadienestyrene lattices, lecithin, lanolin, carnauba wax, candelilla wax, paraffin wax, beeswax, mineral oils, olive oil, hydrogenated coconut and cottonseed oil, glycerine, propylene glycol, glycerol monostearate. Glucose, sorbitol, sugar, corn syrup, cerelose, mannitol, ethyl alcohol, saccharin, titanium dioxide, sodium benzoate, menthol, may also be present.