An In-Vitro Study

Aim and objective-To compare and evaluate the effect of UV stabilizers (UV absorbers and Hindered Amine Light Stabilizers-HALS) on the colour change of a commonly used silicone elastomer subjected to ageing by three different methods. Materials and methods4 groups of 30 samples each were studied; Group A-Control, Group B-Silicone+ UVA (Chimassorb 81),Group CSilicone+ HALS (Uvinul 5050) and Group D-Silicone + Combination (UVA+ HALS) (Chimassorb 81+Uvinul 5050). Each group was further divided into groups of 10 samples each based on the method of ageingaccelerated weathering chamber (Weather-Ometer), artificial perspiration and a cleansing agent. CIE Lab colour values L*, a* and b* were measured for all samples before and after weathering and change in colour (Delta-E) was calculated. One-way ANOVA was applied to compare the mean values of the 4 groups and the Post Hoc Tukey test was carried out to compare between 2 groups. ResultsAll groups showed a significant colour change. For Group A the colour change (average Delta E) for accelerated weathering, artificial perspiration and cleansing agent was 1.479, 0.617 and 0.62 respectively. Similarly, for Group B it was 1.109, 0.509 and 0.507; for Group C it was 1.866, 0.652 and 0.997 and for Group D it was 1.303, 0.829 and 1.033 respectively. UVA (Chimassorb 81) showed the least change consistently in all 3 types of ageing. Conclusion-Addition of UV stabilizer Chimassorb 81 showed a reduction in colour change of the silicone elastomer. Following studies on the effect of these additives on the physical properties of elastomers has shown that they can have a potential use in maxillofacial prosthetic rehabilitation.