Influence of Artificial Weathering on Some Properties of Nano Silicon Dioxide Incorporated Into Maxillofacial Silicone

Background In spite of desirable properties of Silicone elastomers like, easy manipulation, easy coloration, and biocompatibility, it may suffer from degradation after 4-14 months of clinical use. The purpose of this study was to evaluate the effect of addition of silanated SiO2 nanofiller on the tear strength, tensile strength, hardness and surface roughness of A-2186 maxillofacial silicone after artificial accelerated weathering. Material and method 120 samples were fabricated by addition of 5 % SiO2 silanated nanofiller to A-2186 silicone. Based on our pilot study, the 5 % reinforcement revealed superior properties (tear strength, tensile strength, and hardness) among the other percentages (3 %, 4 %). The main study samples were divided into four (4) groups, each group contains (30) samples according to the conducted tests, i. e. tear strength, tensile strength, hardness test, and surface roughness. Then, each group was subdivided into three subgroups according to the artificial weathering environment (A. control before weathering, B. after 200 hours of artificial weathering, and C. after 300 hours of weathering), (n= 10 samples in each subgroups. The samples were tested before and after artificial weathering, and the data were analyzed with a descriptive statistical analysis, one-way ANOVA and post-hoc LSD test. Results The addition of 5 % of SiO2 nanofiller into A-2186 maxillofacial elastomer resulted in a highly increase in mean values of the tear strength, tensile strength and hardness according to the results of our pilot study. After artificial weathering for (200-300 hours), the tear strength and tensile strength values were highly significantly decreased (P 0.01), while the hardness value was highly significantly increased (P 0.01) with aging but still within acceptable clinical limit. A non-significant decrease in surface roughness (Pgreater than0.05) was observed after artificial aging. Conclusion Incorporation of SiO2 nanofiller did not protect the silicone matrix from artificial aging degradation, but can increase the service life of the prosthesis.