The longevity of any prosthesis depends on the materials from which it was fabricated, which is why defects in the material properties may reduce the service life of the prosthesis and necessitate its replacement. This study aims to test the influence of incorporating different weight percentages of thymol micro-powder into the maxillofacial silicone matrix on Shore A hardness of the silicone. Room-temperature vulcanised VST-50 maxillofacial silicone was used to prepare the study specimens. Thymol micro-powder was incorporated into the silicone matrix in two percentages (0.75 wt.% and 1 wt.%). 30 specimens were prepared and then subdivided equally into three groups, with 10 specimens allocated for each group. These study groups are customised according to thymol content percentage: group A: Control (without additive); experimental groups B and C: 0.75 and 1 wt.% thymol additive, respectively. ANOVA and post hoc honesty significant difference tests were utilised for group comparisons (significance level set at P < 0.05). An additional three specimens, one for each study group, were prepared for the fourier transform spectrophotometry analysis. For the Shore A hardness test, there was a non-significant decrease in the reported mean values for both experimental groups (B and C) compared to those of the control group (A) (P > 0.05), while there was no chemical reaction between thymol powder particles and the silicone matrix. In conclusion, the application of thymol micro-powder did not yield a statistically significant reduction in the hardness of the silicone facial prosthesis. This outcome may suggest that the use of thymol micro-powder does not contribute to a more realistic or lifelike appearance of the prosthesis.



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