An impression tray hanger for disinfection

John R. Agar, D.D.S., M.A.,* Douglas B. Law, D.D.S.,** and Henry C. Seymour, D.M.D.*** Walter Reed Army Medical Center, Washington, D.C.

This article describes in detail a method for making a holder for impression trays.

The procedure uses a pattern that can easily he made in the office. A mold is made from the pattern and parts are processed in acrylic resin. Many parts can be made

from the same mold and several holders can be made before it is necessary to remake the mold. (J PROSTHET DENT 1990;63:597-9.)

N ew varieties of life-threatening disease microor- ganisms have emphasized the importance of procedures that prevent the cross contamination of patients or staff members.’ Dental professionals must establish and follow effective infection control procedures to prevent such con- tamination.

This article contains instructions for making a simple device to hold impression trays by the handle for disinfec- tion and transportation (Figs. 1 and 2). The advantages of suspending the impression tray by its handle when excess material cannot be trimmed have been discussed by Rudd et aL2 The tray hanger is designed to fit inside a readily available plastic receptacle with a screw lid, such as an empty irreversible hydrocolloid powder container. The tray holder can be used to immerse impressions in disin- fecting solutions in the plastic receptacle (Fig. 3). The im- pression could also be sprayed with a surface disinfectant while on the stand and then placed inside the container so that the system acts as a humidor during the disinfection process (Fig. 3).

PROCEDURE

A tray hanger model (pattern) is made in two separate parts and a dental stone mold is made of each part. The two parts of the tray hanger are processed separately in acrylic resin, then bonded together. After the stone molds are made, they can be used to produce any number of acrylic resin impression tray hangers.

The pattern for the upright portion of the tray hanger is formed with plastic tubing with 5116 inch and 3116 inch outside diameters reinforced with coat-hanger wire. The

The opinions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the De- partment of the Army or the Department of Defense.

*Colonel, U.S. Army, DC; Director, Prosthodontic Residency Pro- gram.

**Colonel, U.S. Army, DC; Assistant Chief, Fixed Prosthodontics. ***Major, U.S. Army, DC; Senior resident. 10/l/17395

Fig. 1. Impression tray hanger.

dimensions of the hanger are shown in Figs. 4 and 5. Coat- hanger wire l/8 inch in diameter fits snugly inside the 3116 inch tubing, which has an inside diameter of l/8 inch, and the 3116 inch tubing fits snugly inside of 3116 inch tubing, which has an inside diameter of 3116 inch. Short pieces of 3116 inch tubing within the 5116 inch tubing hold the coat hanger wire snug within the larger tubing to give it needed support. The coat-hanger wires are slightly overextended from the plastic tubing.

THE JOURNAL OF PROSTHETIC DENTISTRY 597

AGAR, LAW, AND SEYMOUR

Fig. 2. Hanger with trays.

Fig. 3. Hanger with trays in container for humidor after surface spraying or for immersion disinfection.

Fig.

5 la *

4. Upright portion of tray holder hanger.

PATTERN FOR UPRIGHT

1. Cut one piece each of 5116 and 3116 inch plastic tubing 6 inches long.

2. Cut a straight piece of coat hanger wire 6% inches long. 3. Place the coat hanger wire inside of the 3116 inch tub-

ing; then place the assembly inside the 5116 inch tubing and set it aside. It may be necessary to lubricate the wire and tubing for easier assembly. Several short pieces of of the 3116 inch tubing may be used instead of one whole g-inch piece.

4. Cut two l/2 inch long pieces of 5116 inch tubing, two pieces of 3116 inch tubing 1 inch long, and two pieces of coat hanger wire 1% inch long.

5. Bend the wire in an arc as shown in Figs. 1 and 4 to form the cross arms.

6. Assemble the tubing and wire (Fig. 4). 7. Assemble the three parts (Fig. 4) on a flat surface

according to the measurements in Fig. 4 and fix the curved pieces to the long straight piece with adhesive (Household Goop, Eclectic Products Inc., Carson, Ca- lif.).

PATTERN FOR BASE

1. Make six 1 ‘/z inch lengths of 5/16 inch plastic tubing and reinforce each with 3116 inch tubing and coat-hanger wire.

2. Make a mix of autocuring acrylic resin and form it into a disk approximately 1% inches in diameter and 5/16 inch thick.

3. Place one end of each of the six lengths of reinforced

598 MAY 1930 VOLUME 63 NUMBER 6

Fig. 5. Base portion of tray hanger with dimensions. Side view cross section with reduced portion in underbase.

plastic tubing approximately 3/8 inch into the resin disk arranged like the spokes of a wheel equidistant from each other (Fig. 5). Allow the acrylic resin to set, reinforce the attachment of the tubing to the acrylic resin with adhesive, and let the adhesive set. Grind the center of the bottom of the base so that it is slightly raised, compared with the outer spokes, to increase its stability when the holder is in use (Fig. 5). Cut or drill a 5/16 inch hole through the center of the hub portion of the base (Fig. 5). Note: This step could be done after the base part is processed in acrylic resin.

DENTAL STONE MOLD

1. Make a separate form of boxing wax large enough to ac- commodate each pattern with a land shoulder of ap- proximately 1 inch from each portion of each pattern.

2. Fill each form with a mix of dental stone and smooth the top surface.

3. Place each pattern in its respective box and sink the pattern in the stone to one half the depth of the pattern.

4. When the stone has set, cut orientation indexes in the land of each of the stone investments.

5. Box the stone half flasks, coat the surfaces with a sep- arating medium, and fill each of the boxings with dental stone.

RESIN PARTS

1. When the stone sets, separate the flasks, remove the patterns, and clean the molds.

2. Apply separating medium to the molds and pack the molds with autopolymerizing acrylic resin.

3. Compress the molds until the resin sets, then separate. 4. Recover the parts, remove the flash, round the ends,

finish, and polish the acrylic resin.

ASSEMBLY

1.

2.

3.

4.

5.

Fit the upright into the hole in the base. It should be snug. If the bottom of the base was not ground in step 5 of “Pattern For Base,” it must be done now (Fig. 5). Place the two parts together, with the long part inserted in the hole flush with the bottom side of the base. Apply wet acrylic resin to the junction of the base and the upright with a camel hair brush and allow it to set. Touch up the polish, and the tray hanger is complete.

When the molds for the hanger parts are completed, several parts may be made before it is necessary to remake the mold; however, the pattern should be saved to use again if necessary.

We express our appreciation to Ms. Venetia V&a of the Armed Forces Institute of Pathology for the illustrations in this article.

REFERENCES

1. Council on Dental Materials, Instruments and Equipment, Council on Dental Practice, Council on Dental Therapeutics. Infection control rec- ommendations for the dental office and the dental laboratory. J Am Dent Aeeoc 1988;116:241-8.

2. Rudd KD, Morrow RM, Benge AA. Accurate casts. J PROSTHET DENT 1969;21:545-54.

Reprint requests to: DR. JOHN R. AGAR 1601 OAKLAWN CT. SILVER SPRING, MD 20903

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