Evaluation of the effect of ultraviolet stabilizers on the change in color of pigmented silicone elastomer: An in vitro study.
OBJECTIVE
To compare and evaluate the effect of ultraviolet (UV) stabilizers (Chimassorb 81 and Uvinul 5050) on the color change of pigmented elastomer.


METHODS
Two pigments - Red (P112 Brilliant Red) and Yellow (P106 Yellow) and two UV stabilizers Chimassorb 81 and Uvinul 5050 were studied. A total of six groups of 10 samples each were fabricated using a combination of the above colors and stabilizers: Group A1 - Red control, Group A2 - Red + Chimassorb 81, Group A3 - Red + Uvinul 5050. Group B1 - Yellow control, Group B2 - Yellow + Chimassorb 81, Group B3 - Yellow + Uvinul 5050. All samples were subjected to ageing in an accelerated weathering chamber (Weather-Ometer). Color values L, a, and b were measured at 500 and 1000 h for all samples before and after weathering and change in color (Delta E) was calculated.


RESULTS
All groups showed a significant color change. At 500 h, Chimassorb 81 showed a statistically significant lesser change in both colors (red - 3.66 and yellow - 2.8) compared to their control groups (red - 5.19 and yellow - 4.9). At 1000 h, both UV stabilizers showed lesser color change (A2 - 5.49, B2 - 4.28, A3 - 7.47 and B3 - 4.09) as compared to their respective control groups (A1 - 9.57 and B1 - 5.91). Overall, the change in the color with Group A was more than Group B.


CONCLUSIONS
Addition of UV stabilizers helped the reduction of color change. Chimassorb 81 showed a greater reduction in color change in both colors consistently at 500 and 1000 h.
Department of Prosthodontics, Dr. D. Y. Patil Dental College, Pimpri, Maharashtra, India.
Mohit
M
Kheur
Department of Maxillofacial Prosthetics, Kings College, London, United Kingdom.
Tania
T
Sethi
Department of Maxillofacial Prosthetics, Kings College, London, United Kingdom.
Trevor
T
Coward
Department of Prosthodontics, Dr. D. Y. Patil Dental College, Pimpri, Maharashtra, India.
Dilip
D
Kakade
CIRT, Pune, Maharashtra, India.
M
M
Rajkumar
Color change; maxillofacial prosthesis; pigments; ultraviolet stabilizers