1191 Cosmetic, Nanoclay and Functional Pigment Performance in UVB-Irradiated Facial Elastomers

Saturday, March 24, 2012: 8 a.m. - 9:30 a.m.
Presentation Type: Oral Session
M. BEATTY1, G. POLYZOIS2, B. SIMETICH3, and J. SCHULTE3, 1Research Service/Adult Restorative Dentistry, VA Nebraska-Western Iowa Healthcare System / University of Nebraska, Lincoln, NE, 2Maxillofacial Prosthetics Service, University of Athens (EKPA), Athens, Greece, 3Adult Restorative Dentistry, University of Nebraska, Lincoln, NE

Objectives: This study assessed color and durometer hardness changes resulting from controlled UVB exposures delivered to pigmented PDMS elastomers.  Cosmetic red (CR) and yellow (CY), nanoclay red (NR) and orange (NO), functional intrinsic red (IR) and yellow ochre (IYO), extrinsic red (ER) and yellow ochre (EYO) pigments, plus unpigmented controls (U) were compared.  Methods: 0.1 wt% pigment was mixed into vinyl-terminated PDMS containing 13 wt% silica filler.  Equimolar polymethyl hydrogen siloxane crosslinker was added and the mixture polymerized into discs 34 mm diameter x 6 mm thick.  Each formulation was subjected to UVB radiation (0.72 J/cm2/h,25C,30% r.h.) or control environment (darkness,25C,30% r.h.).  CIEL*a*b* color and durometer hardness were measured at 0, 600, 1800 hours (n=5), and group differences assessed by pigment and environment (ANOVA/Tukey, p≤0.01).  Results: After 600 hours, color changes were imperceptible (ΔE*<1.1), except for UVB-exposed NO (ΔE*=6.8) and NR (ΔE*=11.26,both p≤0.01). Durometer changes for all materials were ≤1.0.  1800 hour results are presented below (mean (s.e.)); capital superscript comparisons are for ΔE*, lower case for ΔDurometer. Comparisons are both vertical & horizontal, p≤0.01.


ΔE* Control


ΔDurometer Control

ΔDurometer UVB


0.5 (0.28)A

0.7 (0.06)A

1.3 (0.38)ab

1.6 (0.31)b


0.6 (0.02)A

1.3 (0.27)A

1.0 (0.08)ab

1.0 (0.35)ab


1.8 (0.35)A

13.4 (0.82)B

0.5 (0.15)a

1.4 (0.47)ab


1.4 (0.08)A

10.7 (0.55)B

0.9 (0.20)ab

1.0 (0.22)ab


0.5 (0.02)A

0.5 (0.06)A

1.2 (0.18)ab

2.0 (0.20)ab


0.9 (0.07)A

1.0 (0.08)A

1.3 (0.14)ab

1.3 (0.22)ab


1.0 (0.19)A

0.6 (0.17)A

0.1 (0.30)a

1.0 (0.46)ab


0.5 (0.13)A

0.9 (0.07)A

0.6 (0.14)ab

1.5 (0.19)b


0.8 (0.03)A

0.7 (0.09)A

1.0 (0.24)ab

1.7 (0.30)b

Conclusions: Except for nanoclay-pigmented materials, color changes were low after 1800 hours UVB exposure. Similar trends were reported previously for micro-sized dye-precipitated clays (IADR 2007,#324). Durometer changes were minimal (≤2.0). Nanoclays were contributed by TNO Science.


Keywords: Color, Dental materials and Prostheses