Assembly of positioning needle and denture mold for positioning denture in plaster cast of the denture mold

An assembly of a positioning needle and a denture mold for positioning a denture in a plaster cast of the denture mold comprises a plastic cast and a positioning needle. The plaster cast has at least one positioning hole. Two sides of the positioning hole is formed with respective first concave portions for positioning the positioning portion; a second concave portion being extended from the first concave portions. A positioning needle includes a rod for embedding the positioning needle into the plaster cast. Two sides of the rod are extended with a pair of protrusions which are symmetrical. A bottom of each protrusion is extended with a positioning portion. Two lateral surfaces of each positioning portion are installed with positioning contact surfaces. The rod has a positioning surface which is vertically connected to the protrusions. Beside, a top of the rod is connected to an assembling portion.