Color stability and colorant effect on maxillofacial elastomers. Part III: weathering effect on color

Maxillofacial prostheses typically last about 6 months before needing replacement due to color and physical property degradation. Prior research has shown that colorants may influence how materials respond to environmental stressors. However, the specific effects of different colorants on elastomer color stability under weathering remain unclear. No prior work had resolved how various colorant types interact with common elastomers during prolonged exposure to environmental conditions. This gap motivated a study to evaluate how colorants affect the durability of maxillofacial prostheses when exposed to natural weathering. It was already known that uncolored materials also degrade over time. But the role of colorants in either accelerating or stabilizing this process had not been systematically tested. This paper's contribution is to provide empirical data on how different colorant-elastomer combinations respond to simulated and real-world weathering. The study addresses the need for better material selection in maxillofacial prosthetics to extend their functional lifespan.

The aim of this study was to assess how different colorant-elastomer combinations respond to weathering and time passage. Specifically, the researchers wanted to determine whether certain colorants could help stabilize elastomer color under environmental stress. The motivation came from clinical observations that prostheses lose color and physical integrity after about 6 months. The study focused on three commonly used elastomers and six types of colorants. By exposing these combinations to controlled and natural weathering, the researchers sought to identify which materials retained their color best. The study also aimed to compare the effects of time passage alone versus exposure to sunlight and weather. This approach allowed them to distinguish between intrinsic aging and environmental degradation. The results could inform material choices for longer-lasting maxillofacial prostheses.

The study involved fabricating 270 specimens using three elastomers and six colorants. Each combination was tested under three conditions: control, time passage, and natural weathering. Control specimens were evaluated within one month of fabrication. Time passage specimens were stored in sealed containers in the dark for six months. Weathering specimens were placed on a dental school roof for six months. Color and optical density data were collected for each specimen. A one-way ANOVA was used to compare color changes across test conditions. When significant differences emerged, the Student-Newman-Keuls test identified which combinations varied the most. The study controlled for variables like exposure time and environmental conditions. This method allowed the researchers to isolate the effects of each test condition on color stability.

Color changes were observed in many colorant-elastomer combinations after weathering. The most significant differences were found in the natural weathering group compared to the control and time passage groups. Some combinations showed minimal color change, while others changed dramatically. The control group had the least color variation, indicating that time alone had a smaller effect than weathering. The time passage group showed moderate changes, suggesting that even in the absence of sunlight, materials degrade over time. The natural weathering group had the highest color variation, especially in combinations using kaolin and liquid cosmetics. Elastomer type also influenced color stability, with Silastic 4-4210 showing less change than others. The study found that some colorants may help stabilize elastomer color under weathering, though results varied by material.

The authors concluded that color changes occur in maxillofacial prostheses due to both time passage and weathering. Some colorant-elastomer combinations showed greater stability than others. The study suggests that the choice of colorant may influence how well a prosthesis retains its color under environmental stress. The results indicate that certain colorants could help stabilize elastomer color when exposed to weathering. However, the authors caution that these findings are specific to the materials tested and may not generalize to all combinations. The study also found that uncolored materials degrade over time, highlighting the importance of material selection. The authors propose that further research is needed to explore how different colorants interact with various elastomers. They also suggest that clinical guidelines should consider the effects of environmental exposure when selecting materials for maxillofacial prostheses.