Dynamic visco-elastic analysis of silicone maxillo-facial prosthetic material using custom-made dynamic visco-elastometer and LASER measuring device

Abstract

Purpose : The dynamic mechanical properties of silicone maxillo-facial prosthetic material are very important for the successful rehabilitation of patients with facial defects. Moreover, it is equally important to determine these properties under conditions similar to those observed in the natural movement of facial tissues. This study evaluates the dynamic mechanical properties of silicone maxillo-facial prosthetic material using the classical Torsional pendulum method and high precision laser based measurement system. Materials and Methods : Five commercially available silicone maxillofacial prosthetic materials A-2002, A-2186, A-VST-50, A-588V-1and MDX4-4210 were taken as sample in the form of cylinders measuring 8X80 mm. A custom-made dynamic visco-elastometer was used to determine the Storage modulus, Loss modulus and Loss tangent over a frequency range of 0.5 to 1.0 Hertz at 37΀Celsius. Results : A-VST-50, A-588V-1 had low loss tangent (P less than 0.05), further they had lower storage modulus than other tested material, which is an added advantage over MDX4-4210 and A-2186. At all test frequencies A-2002 was found to have the highest loss modulus as well as the highest loss tangent (damping factor) among all the five kinds of material tested (P less than 0.05) which indicates its slow response to load but large capacity to absorb energy. Conclusion : Custom-made dynamic visco-elastometer has proved to be reliable, low cost and a convenient instrument to evaluate silicone maxillo-facial prosthetic material. No single material was found to have all the desirable dynamic mechanical properties necessary for maxillo-facial prosthesis applications. Therefore, layering of two or more such kind of materials is recommended to achieve desirable properties.