Universal simplified mold technique for construction of facial prostheses

‘XCTKJN

I. KENNETH

MAXILLOFACIAL

PROSTHETICS

TEMPOROMANDIBULAR

Universal simplified of facial prostheses

JOINT

I_OUI’; l

mold technique

DENTAL

I’DITOR5

AI~ISfvlAh: J. H(.)L:(‘HER

IMPLANTS

for construction

I. Zini,* H. S. Zaki, D.D.S., M.Sc.,** and M. A. Aramany, D.M.D., MS.*** Keqional Center for Maxillnfacial Prosthrtic Rehahilitatton. .Ilcdicinc. Llniversity of Pittsburgh. I’ittshurxh. Pa

C

onstruction of a facial prosthesis that restores function and a lifelike appearance requires artistic and technical ingenuity. Keduction of the time needed to construct a facial prosthesis is an important consideration in health care delivery in hospitals. At the present time multiple procedures are required in the fabrication of facial restorations.’ ’ .4 period of a few days up to a week is generally necessary to complete a prosthesis. The use of stone molds takes time to allow for their complete dryness,‘. ’ whereas mt=tal molds require multiple laboratory steps.’ In addition, more than one patient visit is necessary before the prosthesis is completed. The objective of this article is to present a new and simplified technique for the construction of facial prostheses. Accuracy and time are of prime consideration in this technique.

MATERIALS The impression of the facial structures is made either with revcrsiblc or irreversible hydrocolloid. Silicone 382+ has been found to be a suitable material for construction of the molds. This material, when properly handled and reinforced, serves as an excellent mold to process the facial prosthesis.

MAKING

THE IMPRESSION

Selection of the impression material depends upon the anatomic structures involved. When complex anatomic structures and undercuts need to bc rcproJuced. e.g., in the case of the car, irreversible This work is supported in part by NIH-NC:I-<:N-55184-05. *Artist, Department of Maxillofacial Prosthetics. **Assistant Professor, Department of Maxillofacial Prosthrtics. ***Pmfcssnr of Pmsrhodontirs and Director, Department Maxillofacial Prosthetws. $Silastic 382 medical grade elastomer, Dow Cbrning, Midland. Mich.

56

JULY

1978

VOLUME

40

NUMBER

1

of

Eyr and Ear Hospital,

and School of Dental

hydrocolloid is preferred for making the impression. Reversible hydrocolloid is used where undercuts to he reproduced are minimal and to reproduce soft, displaceable tissues. Scvcral clinicians have used boxing wax to confine the impression material to the face.‘-’ Paperclips have also been used routinely as retention for the plaster backing. In this technique a wax collar is not used to confine the impression material, since the pressure applied to keep the collar in place tends to distort the soft tissues and result in a poorly fitting prosthesis. The hydrocolloid impression material is mixed to a fluid consistency and painted in thin layers to cover the defect and the required margins. A full facial impression and the use of polyethylene tubes for breathing are not always indicated. Partial facial impressions will substantially improve the fit of the prosthesis. especially at the margins, since minimum distortion during impression making can be attained. c\dhesivc paint,* instead of paper clips, is applied with a brush to the impression material after gelation of the hydrocolloid (Fig. 1). Care is exercised to avoid application of the adhesive to the patient’s skin, since it is an irritant. A thin coat of fast-setting plaster of Paris is applied to cover all impression surfaces for reinforcement (Fig. 2). The plaster coat should be applied in two steps; a very thin coat should first be painted and allowed to set. This thin layer will prevent distortion of the underlying facial structures. Then a second, thicker layer of the reinforcing plaster of Paris is added. By this technique, where no breathing tube is used and the reinforcing plaster of Paris is applied in two layers, minimum distortion and maximum tissue ‘Getz Newhold, Crow Village,

Teledyne Ill.

0022-3913/78/01~0-0056t00.40/0

Dental,

Getz-Optow

0 1978

Division.

The C. \‘. Mcaby

Elk

Co.

SIMPLIFIED

MOLD

TECHNIQUE

FOR

PROSTHESES

Fig. 1. A facial impression made with reversible hydrocolloid. Notice the application of adhesive paint before the plaster of Paris backing is used. Fig. 3. The impression

Fig. 2. The impression plaster of Paris.

is reinforced

with

THE

SCULPTURE

Presurgical moulages and photographs, classic sculpturing, and patient observation are used to build the clay sculpture to normal contour and within the natural creases and folds of the face (Fig. 4). Slight asymmetry or modification of the sculpture to suit the personality, sex, and remaining facial characteristics is recommended. The presence of the patient during sculpturing is of paramount importance. Before processing, the sculpture should be

THE JOURNAL

OF PROSTHETIC

DENTlSTRY

her defects

fast-setting

reproduction can be achieved. After the plaster of Paris sets, the impression is removed and inspected for defects (Fig. 3). A cast with artificial fast-setting stone is made and compared to the patient’s face. The working cast is covered in regions designated for sculpture with 0.001 inch tinfoil to facilitate easy removal of the clay sculpture. MAKING

is inspected

Fig. 4. The clay sculpture is tried on for fit final modification of shape, and orientation. tried on the patient’s face for further evaluation and necessary modification. At this time the appropriate basic intrinsic skin tone is selected front a prefabricated shade guide* of the facial materiz.1 MAKING

THE

MOLD

1. Score the master cast with the completed sculpture in three places. Apply silicone 382 in a thin layer with a brush spatula to cover the sculpture and the cast around it, including the three-scored negative indices. 2. Paint on an adhesive *A shade guide is constructed for a range of 30 dilferent intrinsic skin tones. This is done for each facial material on the market and kept in a dark place until nee.ded for shade selection.

57

ZINI,

Fig. 5. The die and counter die with the tinfoil-lined sculpture.

clay

Fig. 7. Patient with an external ear defect. 3. Spread a backing of plaster of Paris evenly over the silicone. The silicone, the plaster of Paris, and the sculpture are removed in one piece. 4. Apply a lubricant to the silicone and the clay sculpture before application of silicone 382 elastomer to make the counterdie. Reinforce the counterdie with a plaster of Paris backing as before. 5. When the material is completely set, open the die and counterdie (Fig. 5). Remove the clay sculpture and clean the silicone mold with acetone solvent (Fig. 6). 58

Fig. 6. The split mold acetone prior to packing.

is opened

ZAKI,

AND

and

ARAMANk

cleaned

with

Fig. 8. The final prosthesis. Note that the margins are placed in natural creases and partly covered by the patient’s hair. Note also that the definite sculpturing and soft curvatures are in harmony with the age and sex of the patient.

MAKING

THE FACIAL PROSTHESIS

1. Preheat the mold in a controlled temperature dry heat oven, following the manufacturer’s recommendations. This step varies with the facial material used. 2. Mix the material, pack in the mold, apply a Cclamp, and place in the oven until the material is JULY

1978

VOLUME

40

NUMBER

1

SIMPLIFIED

MOLD

TECHNIQUE

FOR

PROSTHESES

cured completely. During curing rotate the mold two to three times to prevent porosity, air bubble formation, and pooling of the resin in the mold. 3. After cooling retrieve the prosthesis, trim, and ad,just to the master cast. 4. Try the prosthesis on the patient for fit and marginal adaptation. 5. Properly orient the prosthesis on the master cast with commercial dental adhesive. The adhesive should be applied away from the margins of the prosthesis. 6. Etch the external surface very lightly with a little chloroform or acetone. 7. Apply xylene-suspended pigments for extrinsic coloring while the patient is present. 8. After the proper final shade is achieved cover the prosthesis with talcum powder, wash in running water. and try it on the patient’s face. To prevent color contamination care should be exercised not to touch the prosthesis before talc is applied. 9. If a satisfactory color blend is achieved, position the prosthesis in place using commercial adhesives and/or the natural undercuts (Figs. 7 and 8). If the color does not match, especially at the margins, repeat steps 6 through 8. IO. Give the patient the proper instructions as recommended by several investigators.‘-”

THE JOURNAL

OF PROSTHETIC

DENTISTRY

SUMMARY This article presents a simple procedtlrc for the construction of facial prostheses. The uw of a split mold lined by silicone 382 is recommended. Pertinent information concerning impression making, sculpturing, coloring, and processing to insure esthetically and functionally accrpted prostheses is presented. REFERENCES Kahn, A. 0.. and Boucher, I.. J.: Maxillofacl~d rd I. sew York, 1970, W.B. Saunders Cornpan?. Chalian.

Y. A.. Drane.

facial prosthetics, Williams Company, Brown.

26:54:3,

Mini.

I.,

method

Rcpm DR.

of a nose

19il.

S M.: ‘The

prosthesIs

Maxillo-

\Viliiams

and

,I P~osrrr~r

K.

L..

and

Aramany.

of metallic

M. facial

A

molds.

IXrert

wax

J PROWHET

197.5.

10.

A. ARAMANI

UNIWRSITY SCHOOL

Krill,

X3:8.5,

Standish.

197 I.

for fabrication

reqw.m M.

J. B., and 1. Baltimore, pp 294-298.

K. E.: Fabrication

DEW

Ihxr

ed

Prosthetica, p 115.

OF PIYTSBVRCH OF DEFTAL

PITTSBURGH,

IMEDICINE

P.+. 15213

59