Colour Stability of Two Commercially Available Maxillofacial Prosthetic Elastomers after Outdoor Weathering in Al Jouf Province

Facial prostheses are created from special elastomers modified for their specific physical
and mechanical properties; however, they also show two common major clinical problems: gradual
discolouration of the prosthesis over time in service environment and deterioration of static, dynamic,
and physical properties. As a result of external environmental factors, facial prostheses may become
discoloured and discolour by changing colour from intrinsic and extrinsic colouring, and this is
associated with the intrinsic colour stability of elastomers and colourants. Thus, in this in vitro
study, a comparative evaluation of the effect of outdoor weathering on the colour stability of A-103
and A-2000 room-temperature vulcanised silicones used for maxillofacial prosthesis was conducted.
To accomplish this study, a total of 80 samples were fabricated, 40 samples of each material were
grouped as clear (20) and pigmented (20). These samples were mounted on wooden board and the
assembly was placed on the roof of the dental school from October 2021 to March 2022. To maximise
the amount of sunlight on the specimens, the exposure rack was set on five 68 angles from horizontal
and also to prevent standing water. The specimens were left uncovered during exposure. The testing
of samples was conducted with the help of a spectrophotometer. The colour values were recorded
in the CIELAB colour system. It describes the three colour coordinates (colour values) x, y, and z
in three new reference values of L, a, and b, aiding in numerically classifying colour differences.
After 2, 4, and 6 months of weathering, testing was conducted using a spectrophotometer and the
colour change (DE) was calculated. The A-103 RTV silicone group with pigmentation showed the
maximum change in colour after six months of environmental conditioning. The data for colour
difference within groups were analysed using a one-way ANOVA test. Tukey’s post hoc test assessed
the pairwise mean comparison’s contribution to the overall significant difference. The nonpigmented
A-2000 RTV silicone group showed the maximum change in colour after six months of environmental
conditioning. After 2, 4, and 6 months of environmental conditioning, pigmented A-2000 RTV silicone
showed better colour stability than A-103 RTV silicone. The patients requiring facial prosthesis do
need to work on outdoor fields, and thus weathering will have deleterious effects on such prosthesis.
Hence, the selection of appropriate silicone material with respect to the Al Jouf province region is
crucial, which includes economic, durable, and colour stability.