Preventing Accidents with Demonstration Casts

When plaster casts are used for table clinics, case presentations, or other demonstrations, there is always a possibility that they can be dropped, breaking some of the teeth, or unintentionally rearranged. I have found a way to keep casts on the table by implanting magnets in their bases.

Small magnets made of samarium cobalt or neodymium iron boron can be used. To prevent corrosion, cover each magnet with a sheet of polyvinylchloride in a vacuum-forming machine. Make a hole for the magnet in the base of the cast (Fig. A), then insert the magnet, and plaster over the hole. The patient identification label can be added to cover the repair site (B).

To prepare the table, affix some self-adhesive double-sided stickers in the locations for the demonstration casts. Cut thin stainless steel bases to the size of the plaster cast bases, and stick these to the table with the adhesive (Fig. C). Set the casts over the stainless steel bases so that the magnets hold them in place (Fig. D). The same procedure can be followed to place the casts in an occlusal view (Figs. E,F).