3M ESPE Fabricating the Wax Pattern in the Dental Office, Spruing The Alginate Lower Container

Figure 14

Figure 15A

Figure 15B

Figure 15C

Figure 16

Figure 17

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Fabricating the Wax Pattern in the Dental Office

A wax injector enables the ability to fabricate the wax pattern in the dental office and modify this custom occlusal rim and take all the patient records on the same appointment as the impression. (Figure 14).

The optimum injecting temperature is 170–190°F. This temperature is typically reached by setting the injector at the Medium/High position. It will take about 20 minutes to reach this temperature from a "solid" state. Experiment with your injector to find the optimum position for injecting. Mark this position on your machine for future reference.

Spruing The Alginate Lower Container

Entrance Sprue Hole: Using a thin tapered bur, approximately 1/8" in diameter (determine the size bur that works best for you), drill a hole through the anterior of the container entering the void created by the denture. The sprue hole should be started approximately in the middle of the container, not near the containers ledge, and enter the void above the ANTERIOR TEETH IN THE ANTERIOR FLANGE (Figure 165, 165, 15C).

Do not have the sprue hole enter the midline of the anterior teeth as the anterior teeth need to be accurately represented in the wax pattern. The hole can also be made using a cork boring tool or small 3/16" thin straw, once a small hole is cut through the container (Figure 16).

Exit Sprue Hole(s): The exit sprue for the maxillary arch can be made similarly as the entrance sprue and should exit the distal end of the impression void. The exit hole should be directly opposite the entrance hole for the maxillary arch. If you prefer, you can make 2 exit holes in the maxillary arch — one at one at each distal end of the maxillary denture. Be sure to make these holes at the “highest point” of the void when held vertically, as to allow the wax to fill the entire void before exiting. In the mandibular arch there is one entrance sprue hole and two exit holes — one at each distal end of the mandibular denture, exiting the distal retromolar area (Figure 17). Note: Be careful not to make the exit holes in an area where the stone cast will cover the holes. These holes must be made in the void itself.