| The SY-1 room temperature vulcanizing maxillofacial elastomers developed by the Fourth Military Medical University are mainly used in the repair of maxillofacial soft tissue defects. The research fell into two parts.Part I The effects of ozone aging on the mechanical properties of SY-1 silicone elastomersIn order to evaluate the effects of ozone aging on the mechanical properties of SY-1 silicone elastomers, the hardnesses (Shore-A), tensile strengths, elongations at break, permanent deformation rates and tear resistances before and after ozone aging treatment were measured in accordance with the National Standards, and then the results were analyzed statistically. The results showed: 1. The hardness of the SY-1 elastomer treated by ozone aging was changed from 24 to 30, which was however within the ideal range, and the elastomer could well match the maxillofacial skin and so was suitable for the repair of maxillofacial soft tissue defects. 2. No significant differences were detected in tensile strengths, elongations at break, permanent deformation rates and tear resistances before and after the ozone aging treatment (P>0.05), which indicated that the SY-1 elastomer exhibited excellent ozone aging resistant properties and could be used as prostheses for the repair of maxillofacial soft tissue defects.Part II Effects of multi-factors on the color stability of SY-1 silicone elastomersWith the development of material science, aging resistant physical and mechanical properties have been greatly improved. As a result, refabrications due to the aged prosthesis color are on the rise. In order to explore into the effects ofvarious aging factors on the color stability of the SY-1 silicone elastomer so as to select the best pigments for clinical application. Consulting 1976 CIE LAB standards of chromatic aberration, we analyzed the effects of 4 aging factors, (thermal aging, ozone aging, outdoor aging and time pass) on the color stability of SY-1 silicone elastomers painted with three color series (gouache color, oil pigment and inorganic salts). The results were as follows.1. There were differences in color stability under different aging conditions.2. Under the thermal aging condition, the SY-1 silicone elastomers stained with oil pigment and inorganic salts showed better color stabilities than that with gouache color.3. Under the ozone aging condition, the SY-1 silicone elastomers stained with oil pigment and inorganic salts showed better color stability than that with gouache color.4. Under the outdoor weathering condition, all the SY-1 silicone elastomers, whether stained with oil pigment, inorganic salts or gouache color, underwent color changes but the elastomer stained with oil pigment possessed better color stability than those stained with other color series.5. Under the time pass condition, all the SY-1 silicone elastomers also underwent color changes but to a lesser degree than the changes under the outdoor weathering condition, and the elastomers stained with oil pigment and inorganic salts possessed better color stabilities than that stained with gouache color.6. Comprehensive data indicated that oil pigments possessed excellent heat and ozone aging resistant, light and weather tolerant properties and better color stability than the other two series, so they are suitable for clinical application. |
