Colour Difference Between Caucasian and Afro-Caribbean Skin Tone Silicone Elastomer Moulded in Type II and Type III Dental Stone.

Aim: The colour stability of the silicone is essential for the longevity of facial prostheses. This in vitro study investigates the colour degradation of two different skin shade silicones moulded in Type II and Type III dental stone.

Methods & Materials: Two different types of dental stone were used to fabricate 168 silicone samples (n=42 for each group) using M511 maxillofacial silicone, which was coloured with Spectromatch Procolourants. The polymerisation was carried out at 85°C 1.5 hours. A spectrophotometer was used to record the colour differences (ΔΕ) of each group before and after polymerisation. The CIEL*a*b* formula was used to obtain the measurements and a one-way ANOVA was carried out for the statistical analysis of the data.

Results: There is a statistically significant colour difference (ΔΕ) for all groups. For the Afro-Caribbean skin tone, Type III dental stone demonstrated the greatest colour change (ΔΕ = 4.36), whereas, for the Caucasian skin tone, it was the Type II dental stone (ΔΕ = 2.21).

Conclusion: This study showed that regardless of the investing material, the colour of the silicone lightens after polymerisation. Both types of dental stone resulted in visible colour changes, with a ΔΕ ranging from 1.64 - 4.36.