PLASTICS IN THE FORM OF PASTES OR POWDERS FOR TOOTH CROWNS, TOOTH BRIDGES, ARTIFICIAL TEETH AND PLASTIC PROSTHESES; PLASTICS FOR USE AS MODELLING MATERIAL FOR DENTAL PURPOSES; IMPRESSION MATERIAL FOR DENTAL USES, DENTAL FILLERS, DENTAL LACQUERS, INSULATING MATERIAL FOR DENTAL USES, SUCH AS GYPSUM MODELS FOR THE MANUFACTURE OF PLASTIC TOOTH PROSTHESES; DRYING MATERIAL FOR TEETH