MODELLING PASTES, INCLUDING THOSE PUT UP FOR CHILDREN'S AMUSEMENT; PREPARATIONS KNOWN AS DENTAL WAX OR AS DENTAL IMPRESSION COMPOUNDS, PUT UP IN SETS, IN PACKINGS FOR RETAIL SALE OR IN PLATES, HORSESHOE SHAPES, STICKS OR SIMILAR FORMS; OTHER PREPARATIONS FOR USE IN DENTISTRY, WITH A BASIS OF PLASTER (OF CALCINED GYPSUM OR CALCIUM SULPHATE)