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)