Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers

Statement of problem. Oil-based pigments are added to a maxillofacial prost hesis either as base colorants present within the elastomer or as surface t ints that art painted on with an adhesive. Color stability of the pigments and pigmented prosthetic materials on exposure to ultraviolet radiation are unknown. Purpose. This study measured Delta E-star color changes caused by ultraviol et radiation for materials colored with 5 oil Figments, applied either as b ase colorants (intrinsic) or:surface tints (extrinsic) to a silicone elasto mer. Material and methods. One: of 5 oil pigments was added to polydimethyl silo xane disks to serve as a base colorant (0.2 weight percent present througho ut a 2 nim thick disk) or Its a concentrated surface tint (2.0 weight perce nt concentrated in upper 0.3 mm thickness). Pigmented disks, along with pig ment-only and elastomer-only control disks, were exposed to ultraviolet rad iation for 400, 600 and 1800 hours. Delta E-star color changes were measure d at baseline and for each tints interval. Results. Control samples underwent minimum color changes after 1500 hours ( Delta E(star)less than or equal to 2.0), whcrc3s samples containing oil pig ments as base colorants demonstrated a wide range of susceptibility to ultr aviolet radiation with the greatest changes occurring for pigments cadmium red, cadmium yellow, and yellow ochre (7.1 less than or equal to Delta E(st ar)less than or equal to 9.4). Elastomers coated with the same oil pigments as concentrated. surface tints demonstrated significantly lower color shif ting after 1500 hours of radiation exposure (maximum Delta E-star=4.2, P le ss than or equal to.05). Conclusion. Customizing a prosthesis with an oil-pigmented surface tint may reduce the incidence of color change, provided a. sufficient amount of pig ment is present.