Technique for boxing an altered cast impression

Kevin D. Plummer, D.D.S.* United States Army, APO N.Y.

L aboratory management of altered cast impressions can be confusing, time consuming, and error producing for the dental laboratory technician and the dentist. The technique described eliminates beading and typical

The views or opinions expressed herein are the private ones of the author and are not intended to be construed as otTicia1 or as

reflecting those of the United States Army. *Captain, IX. 1.rF-A. 39th Med. Det.

Fig. 1. Sheet of boxing wax with 6 mm margin encloses impression.

Fig. 2. Framework is luted to master cast with sticky wax.

boxing which can lead to distortion of the impression by heat and pressure and, in addition, expands on a boxing method described by Groves and Broering.’

TECHNIQUE

1. Form a sheet of boxing wax on a flat plastic sheet. The wax should enclose the impression providing at least 6 mm of margin around the impression (Fig. 1).

Figs. 3 and 4. Framework with corrected impression is seated into a plaster mix contained bv wax boxing sheet.

THE JOURNAL OF PROSTHETIC DENTISTRY 573

PLUMMER

Fig. 5. Boxing wax placed around plaster base and cast leaving at least 20 mm from top of wax to highest point on impression.

Fig. 7. Stone cast separated from the impression.

Fig. 6. Final pour of stone into boxed impression.

2. Trim the distal extension(s) from the master cast in a typical manner.

3. Introduce mechanical locks into the master cast to accept the new stone to be added.

4. Attach the framework/impression to the master cast with sticky wax, making sure the framework is positioned correctly (Fig. 2).

5. Mix 50% cornstarch (Argo Cornstarch, Best Foods Div. C.P.C. International Inc., Englewood Cliffs, N.J.) and 50% white modeling plaster by volume with water to a creamy consistency. Pour this into the boxing wax form.

6. Place the impression in the mixture. Fill the tongue space, seal around the framework, leaving approximately 3 mm of the border of the impression exposed (Figs. 3 and 4).

7. Allow the mixture to set for 10 minutes. 8. Remove and save the boxing wax.

Fig. 8. Framework after removal of impression is reseated on master cast.

9. Trim the land of the cast to your specifications. 10. Seal the previously used boxing wax to the

trimmed base leaving at least 20 mm from the top of the boxing wax to the highest point on the impression (Fig. 5).

11. Soak the master cast in slurry water for 5 minutes.

12. Pour the cast using the same stone as the original master cast. No separating medium is needed (Fig. 6).

13. When the stone is set, remove the boxing wax and place the cast in a water bath of 110” F to facilitate removal of the plaster/cornstarch mixture and the framework.

14. Separate the plaster/cornstarch mixture with plaster pliers and your fingers. Remove the framework (Fig. 7).

15. Finish the cast to your specifications (Fig. 8).

574 MAY 1982 VOLUME 47 NUMBER 5

BOXING ALTERED CAST IMPRESSION

SUMMARY

An alternate method is presented for laboratory

management of altered cast impressions. This tech- nique provides a quick, reliable method that reduces the possibility of laboratory mismanagement. It is also an alternate to techniques by Bolouri et a1.2 and McCracken.’

REFERENCES

I f~~o\c. If.. ,mtl Brorrinq. L. F.: Impression boxing and cas [IW’iI,~. 1 ~‘ROSTllK~ I)r:VT 43:t 12, 1980.

Rqmnr requests tri-

KEVIN D. PLUMMER. CAPTAIN DC 255968864

US.4 DENTAL CLINIC LUDWICSBURG C/O 29TH MED DET. APO NY 09154

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Surface topography of the enamel margins of butt and beveled Class V preparations D. H. Retief, M.Sc., B.D.S., Ph.D.(Dent.), E. Woods, B.S., H. C. Jamison, D.D.S., Dr. P.H., and F. R. Denys, M.S.

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THE JOURNAL OF PROSTHETIC DENTISTRY 575