SECTIONEDITORS

chnique Tsnn University

Ma, DMD,

for fabrication MS,a

of Washington,

and Morna School

A technique for fabrication silicone elastomer supported DENT 1992;68:940-2.)

of Dentistry,

of interim

midfacial

prosthes

Johnsonb Seattle,

of interim midfacial by cellulose acetate

Wash. prostheses matrix

using maxillofacial is described. (J PROSTHET

T

he prosthetic management of midfacial defects has been documented.lW6 The sequence of prosthetic rehabilitation includes presurgical consultation, intraoral surgical prosthesis, and interim extraoral and intraoral prostheses followed by definitive prostheses. Interim intraoral and extraoral prostheses can be made and delivered 2 to 4 weeks after surgery. Interim midfacial prosthesis, also known as facial shield,2, 7 can provide the patient with normal facial anatomical features. The interim midfacial prosthesis is usually made from hard acrylic resin and often is relined with tissue-conditioning material2 or autopolymerizing resilient denture line@,” during the healing period. The primary disadvantage of using acrylic resin is its rigidity. Adaptation of an interim prosthesis around the surgical defect is compromised by movable tissue. The rigid margins of the acrylic

aAssistant Professor, Department of Prosthodontics. bMaxillofacial Prosthetics Technician. 10/l/41382

Fig. 1. Preoperative master cast fabricated. 940

2. Anatomic contour of tumor site corrected on master cast.

Fig.

Fig.

3. Duplicate of master cast.

DECEMBER1992

VOLUME68

NUMBER6

INTERIM

MIDFACIAL

PROSTHESES

Fig. 4. Vacuum-formed matrix tried on patient trimmed to desirable location for margin.

and

Fig. 6. Vacuum-formed matrix placed on bottom half of duplicate master cast.

Fig. 7. External coloration of interim midfacial prosthesis completed. Fig. 5. Waxing of interim midfacial prosthesis. Margins are overextended to allow trimming at delivery.

resin prosthesis may also cause discomfort to adjacent tissue. Another disadvantage of using acrylic resin for interim midfacial prostheses is color-matching at the margin of the prosthesis. Maxillofacial silicone elastomer has been used in the fabrication of transitional facial prostheses.8 The advantages of silicone elastomer are flexibility and better colormatching. However, a moderate amount of material thickness is required to achieve sufficient rigidity to prevent the

THE

JOURNAL

OF PROSTHETIC

DENTISTRY

prosthesis from collapsing during function. A thicker prosthesis will have a heavier weight, which makes retention more difficult, especially in large facial defects. The following technique describes the fabrication of a light-weight interim midfacial prosthesis by use of silicone elastomer with a rigid backing made from vacuum-formed clear acetate.

TECHNICAL

PROCEDURE

1. A facial moulage impression is made with irreversible hydrocolloid and a master cast is fabricated in dental stone (Fig. 1). 2. The master cast is recontoured and waxed to the 941

MA

AND

JOHNSON

7. One layer of baseplate

8. 9.

10.

11. 12.

ig. 8. Interim

midfacial

prosthesis

delivered

to patient.

desirable contour if anatomic deformation exists at site of tumor (Fig. 2). The master cast is soaked in soapy water and duplicated with irreversible hydrocolloid. The duplicate cast is fabricated in dental stone. Some areas on the duplicate master cast may need to be trimmed 1 to 2 mm to allow for thickness of material needed to reproduce a desirable anatomic contour of the interim prosthesis. The nasal contour on the duplicate master cast is trimmed 2 mm for the interim midfacial prosthesis as described in this article (Fig. 3). The border of the duplicate master cast is trimmed to allow proper placement on the platform of a vacuum adaptor (Sta-Vat, Buffalo Dental Mfg. Co. Inc., Syosset, N. Y.). A cellulose acetate matrix of 0.02 inch thickness is adapted to the duplicate master cast by use of the vacuum adaptor. The cellulose acetate matrix is trial fitted on the patient and used as a template to locate the desirable extension of the interim prosthesis (Fig. 4). The acetate matrix within the interim midfacial prosthesis is used as support only. The border is trimmed away from the movable tissue of the midfacial defect, to allow the flexible silicone elastomer margins to contact the facial tissue of the patient. Several acetate matrices may be fabricated and stored for later use, especially if flasking of the wax sculpting is planned, because it is difficult to fabricate a cellulose acetate matrix from the master cast after it is invested in a flask.

942

wax is adapted to the matrix and wax sculpting of the interim prosthesis is completed (Fig. 5). The top half of the mold is poured in dental stone. Cellulose matrix is placed on the bottom half of the mold, and colored silicone elastomer with its curing agent (MDX4-4210 medical grade silicone elastomer and curing agent, Dow Corning Corp., Midland Mich.) is placed in the top half of the mold (Fig. 6). The silicone prosthesis is processed under water at 160’ F for 8 hours. After processing, the prosthesis is fitted on the patient, and the border of the prosthesis is trimmed. External coloring is applied if necessary (Fig. 7). The prosthesis is attached to patient’s spectacles and held in place with adhesive skin tape (Fig. 8). With use, the acetate matrix may separate from the silicone material. If this happens, they can be reattached with cyanoacrylate adhesive.

SUMMARY The interim midfacial prosthesis uses a rigid backing support with flexible margins and can be made with most types of commercially available medical grade silicone elastomers. The technique may be modified for fabrication of definitive midfacial prostheses. The disadvantage of the technique is that an extra step is required to make a duplicate master cast, and a vacuum adaptor is needed.

REFERENCES 1. Metz HH. Maxillofacial prosthetic rehabilitation after mouth and face surgery. J PROSTHET DENT 1964;14:1169-77. 2. Cantor R, Curtis TA, Rozen RD. Prosthetic management of terminal cancer patients. J PROSTHET DENT 1968;20:361-6. 3. Lepley JB, Strauss PW. Functional and cosmetic restoration of a massive orofacial defect. J PROSTHET DENT 1973;30:635-6. 4. Tautin FS, Schoemann D. Retaining a large facial prosthesis. J PROSTHET DENT 1975;342-5. 5. McClelland RC. Facial prosthesis following radical maxillofacial SUIgery. J PROSTHET DENT 1977;38:327-30. 6. Marunick MT, Harrison R, Beumer 3. Prosthodontic rehabilitation of midfacial defects. J PROSTHET DENT 1985;54:553-60. 7. Beumer J, Curtis TA, Firtell DN. Maxillofacial rehabilitation. St. Louis: CV Mosby 1979:343-5. 8. Birnbach S, Herman GL. Coordinated intraoral and extraoral prostheses in the rehabilitation of the orofacial cancer patient. J PROSTHET DENT 198%343-B. Reprint

requests

to:

DR. TSUN MA DEPARTMENT OF PROSTHODONTICS, UNIVERSITY OF WASHINGTON SCHOOL OF DENTISTRY SEATTLE, WA 98195

SM-52

DECEMBER

1992

VOLUME

68

NUMBER

6