technique ostheses

for preparing

a polyurethane

~~~~

James C. Lemon, DDS,” Jack W. Martin, DDS, MS,b and Gordon E. King, DDSC The University of Texas M. D. Anderson Cancer Center, Houston, Texas A simplified technique for preparing, under a vacuum, a polyurethane lining for a facial prosthesis is described. A previously presented technique strengthened the prosthesis and allowed it to be attached with a water-based adhesive. This technique eliminates wrinkling, simplifies bonding, allows multiple linings to be made at the same time, conserves time and cost, and improves predictability of the results. (J PROSTHET DENT 1992;67:228-9.)

he technique of placing a thin polyurethane liner silicone facial prostheses was described by Udagama.l This technique (1) enhancesthe edgestrength of silicone prostheses,(2) permits retention with waterbasedskin adhesives,and (3) provides an effective method to feather and maskthe margins.Problemsassociatedwith this technique include (1) wrinkling and folding of the urethane sheet over irregular contours and (2) retention of polyethylene tags that prevent bonding of the silicone to itself or to the polyurethane sheet. A modified technique is described that prevents these problems and that decreasesthe risk of damage to the polyurethane sheet during packing. Such damagedelays completion of the prosthesis.

2. Place an 0.004 inch urethane sheet (polyurethane sheeting, Factor II, Lakeside, Ariz.) in a vacuum-adapter machine (Buffalo Manufacturing, Buffalo, N.Y.) and secure it with a clamp. 3. Under an evacuation hood, cleanthe superiorportion

1. Prepare stone molds and fabricate a perforated duplicate cast (Figs. 1 and 2). aAssistant Professor, Department of Dental Oncology. bAssociate Professor, Department of Dental Oncology. cProfessor, Department of Dental Oncology.

Fig.

2. Perforated duplicate cast (left).

10/l/29118

Fig. Fig.

228

1. Completed mold for auricular prosthesis.

3. Urethane lining adapted to perforated duplicate

cast.

FEBRUARY1992

VOLUME61

NUMBER2

POLYURETNANE

LINING

FOR

FACIAL

PROSTHESES

Fig. 4. A, Auricular defect. B, Auricular prosthesis prior to extrinsic coloration. C, Completed auricular prosthesis.

of the sheet with reagent-grade acetone by rubbing it with a 2 x 2 inch gauze sponge. After the sheet is dry, repeat the cleaning procedure. 4. Raise the unit and heat the urethane sheet until it becomes soft (approximately 2 minutes) and begins to sag beneath the frame. 5. ‘1‘1lrn on the vacuum and adapt the lining to the perforated (ltiplicate cast (Fig. 3). 6. With the vacuum still on, apply primer S-2260 (Dow Corning Corp., Midland, Mich.) to the lining with cotton gauze. Do not contaminate the primed surface. After adequate cooling, turn the vacuum off and allow the primer to set for a minimum of 1 hour. 7. After 1 hour, mix silicone elastomers (MDX4-4210 and Silastic 891 medical adhesive type A, Dow Corning Corp.) and oil base pigments to obtain an appropriate color match. Cover the mixture to retard setting. 8. Apply a thin coat of nontinted medical adhesive type A to the primed side of the urethane sheet. The vacuum is active to minimize movement of the lining. Remove the lining and place it on the tissue side of the mold. Place pre-

THE

JOURNAL

OF PROSTHETIC

DENTISTRY

viously mixed silicone (MDX4-42iO and Silastic 891) into the mold and pack it under pressure. Polymerize the prosthesis in the manner desired. 9. After the prosthesis is polymerized, remove it from the mold (Fig. 4). SUMMARY This technique results in a more flexible and adaptable urethane liner, and problems caused by polyethylene tags are eliminated. In addition, cost is reduced because type A adhesive and the primer are applied only to the part of the lining required for the prosthesis. REFERENCE 1. Udagama DENT

A. Urethane-lined

silicone

facial

prostheses.

J PR~ST~ET

1987;58:351-4.

Reprint requeststo: DR. JAMES C. LEMON DEPARTMENT OF DENTAL ONCOLOGY, Box 9 UNIVERSITY OF TEXAS M. D. ANDERSON CANCER 1515 HOLCOMBE BLVD. HOUSTON;, TX 77030

CENTER

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