Biomedical subjects
Publications and source records attributed to A Udagama.
After testing a variety of materials to line the tissue-fitting surface of silicone prostheses in an attempt to render them adheophilic, tear-resistant, wettable, smooth, and resistant to fungal growth, a vacuum adaptable thermoplastic prefabricated thin urethane film was found to be most effective. A technique is described for fabricating a silicone prosthesis with such a lining.
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The urethanes, PVC, acrylic resins, and silicones are still the most popular among a large number of materials being used to fabricate facial prostheses. Each material has advantages and disadvantages. The ideal material is not yet available. It was found that Silastic medical adhesive type A, a preparation of methyl triacetoxy silane crosslinked silicone, possesses a wide range of biologic, clinical, and technical advantages over other materials. However, the poor adheophilic properties of this material remain its most significant disadvantage. A processing technique for methyl triacetoxy silane crosslinked silicone is presented. Further investigations are being conducted to improve this material.
The bond interface between Silastic 891 and methyl methacrylate was evaluated to determine whether the use of primers would prevent leakage. Three different primers were tested, and the amount of leakage at the bond interface was evaluated by placing the test samples in India ink for periods of 12, 24, and 48 hours and 2 weeks. Of the 80 samples studied, 73 showed evidence of leakage-most of which occurred during the initial 12-hour test period.
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This method of fabrication of an immediate nasal prosthesis has distinct advantages which recommend its use. These are (1) the use of an RTV silicone rubber impression as the refractory cast cuts fabrication time to minutes rather than hours, as compared with other methods of fabricating a nasal prosthesis; (2) the RTV silicone is permanent and stable and provides an exact reproduction of the part to be excised; (3) the initial RTV silicone impression may be used during fabrication of the definitive prosthesis as the mold for production of a wax sculpting model; (4) PVC prostheses offer a unique advantage of being soft enough for trimming with scissors at the time of surgery and are flexible and tissue-compatible; and (5) psychological trauma is minimized and the patient is better prepared for a definitive prosthetic restoration.