ABSTRACT: 0131

Outdoor Weathering of Facial Elastomers Containing Glass Pigments

M.W. BEATTY, Nebraska-Western Iowa Health Care System, VA Medical Center, University of Nebraska Medical Center College of Dentistry, Lincoln, USA, G.K. MAHANNA, University of Nebraska Medical Center, College of Medicine, Omaha, USA, K.M. LEWIS, Momentive Performance Materials, Tarrytown, NY, B. SIMETICH, University of Nebraska, Lincoln, USA, and J. SCHULTE, University of Nebraska-Lincoln, USA

Objective: Intrinsic colorants in facial prostheses fade after repeated exposures to outside weathering. Since stained glass maintains its color after centuries of weathering, this study's purpose was to evaluate colored glasses for potential use as intrinsic colorants in maxillofacial prosthetic materials. Methods: Red (RG) and yellow (YG) glass powders (Kugler) were sieved to produce particle diameters < 38 um. To achieve color saturation, powders were mixed 10% by weight into silica-filled, vinyl-terminated polydimethyl siloxane. For comparison, pigmented mixtures containing functional intrinsic red (IR), extrinsic red (ER) intrinsic yellow (IY), extrinsic yellow (EY) were prepared (Factor II), plus an unpigmented mixture (U). After polymerization, dumbbells conformed to ASTM D412 dimensions and 6 mm thick discs conformed to D2240 for Shore-A tests (all n=5). Materials either were weathered outdoors for 1000 h or stored in darkness. Changes in L*a*b*E* color (dumbbells) and Shore-A (discs) were measured and compared according to pigment and test condition (ANOVA/Tukey). Results: Greater color parameter changes were noted in weathered specimens compared to controls (p≤0.05), but Shore-A hardnesses were similar. In the table below, mean±se values for outside weathering are shown; all superscript comparisons are horizontal (p≤0.05)

	RG	IR	ER	YG	IY	EY	U
ΔL*	-0.2 (0.07)^a	0.1 (0.05)^a	-0.9 (0.70)^a	-1.0 (0.17)^a	-9.4 (0.25)^b	-9.2 (0.38)^b	-1.3 (0.42)^a
Δa*	-1.1 (0.09)^a	-0.6 (0.23)^a	-0.3 (0.35)^a	-0.2 (0.02)^a	2.7 (0.16)^b	3.3 (0.08)^c	-0.1 (0.02)^a
Δb*	-1.1 (0.09)^a	-1.0 (0.34)^a	-2.0 (1.07)^a	-1.7 (0.20)^a	-13.8 (0.46)^c	-13.3 (0.43)^c	1.0 (0.13)^b
ΔE*	1.6 (0.13)^a	1.3 (0.37)^a	2.5 (1.28)^a	2.0 (0.24)^a	17.0 (0.51)^b	16.5 (0.51)^b	1.9 (0.30)^a
ΔShore	0.6 (0.66)^a	0.6 (0.26)^a	1.2 (0.30)^a	-0.4 (0.64)^a	2.8 (0.46)^b	3.2 (0.43)^b	0.9 (0.32)^a

Conclusions: Few differences were noted among red pigmented elastomers. For yellow pigmented materials, yellow glass produced the fewest changes in color and hardness. Supported by VA Rehabilitation R&D grant A4290I.

Seq #34 - Materials and Remineralization; Elastomers; Mechanical Testing
9:45 AM-11:15 AM, Thursday, April 3, 2008
Hilton Anatole Hotel Grand Ballroom A

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