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)