Studies On The Operational Characteristics Of A New Maxillofacial Silicone Elastomer SY-1

SY-l room temperature vulcanizing silicone elastomer (RTV扴) is a newly developed maxillofacial prosthetic elastomer. In order to provide the technicians with the basis that in turn will standardize the manufacturing procedure in fabricating maxillofacial prosthesis, and to help choose the carrier of the pigments; the studies on the operational procedures including defining the ratios of cross- linker to base, vacuum-pumping times and the accurate relation between curing temperature and curing time were all carried out in accordance with the SY-l 憇 physical properties such as tensile strength, elongation at break, tear strength and Shore A hardness. The surface texture played an important role in the mechanism of micro trauma. The study on the compact of different treating methods on surface texture of SY-1 elastomer after vulcanizing can also offer us to what extent did the prosthesis simulate the skin on the aspect of feeling or touching. The treating methods on the surface of gypsum molds turned out to be a vital procedure to the fabrication of the prostheses. In order to provide the prostheses made of silicone elastomer with carrier of pigments in extrinsic coloring, the adhesive strength of the two kinds of bonding agents were evaluated respectively. The results are shown below: 1 .The better physical properties would be achieved as the quality ratios of cross-linker to base were set 1%. The combine of high tear strength and high elongation at break can be obtained then; the mean values were 18.2kNIM and 440% respectively. The mean values of tensile strength and ShoreA hardness were 4.OMpa and 24 respectively. Both higher and lower quality ratios will make the -3- physical properties unfit for the fabrication of prostheses. 2. Pumping 20mm for vacuum after stirring turned out to be most fit for the fabrication of prostheses. The combine of high tear strength and high elongation at break can be obtained on doing so; the mean values were 18.OkN/M and 470% respectively. The mean values of tensile strength and ShoreA hardness were 4.lMpa and 25 respectively. Either longer or shorter pumping time will make the physical properties unfit for the fabrication of prostheses. 3. The clinical curing times of SY-l were much longer than the curing times measured with vulcanizing machine under the same temperature and the clinical ones should be followed when making the maxlllofacial prostheses with SY-l. The clinical curing times under 200C~. 400(2 600(2 800(2 and 1000C were about 21 7.5~. 4.5~. 2 and 1 hours respectively. 4. The surfaces treating with silicone grease proved to be the smoothest ones among five treating methods, not only according to the parameters measured with apparatus, but also to the characteristics of electron-scanning microscope images. The surfaces of the prostheses that contact the tissue made under this treating method can decrease the possibility of micro trauma. While the surface treated with soap solution had electron-scanning microscope images that were similar to the ones of an old woman抯 skin. Prostheses fabricated under this treating method can simulate the skin to a higher extent. 5. The adhesive strength of Adhesive-A was comparatively higher than that of SDG-A(m). There are still much to be done to improve the adhesive strength of SDG...