title: Effect of Incorporation of Nano-Oxides on Color Stability of Maxillofacial Silicone Elastomer Subjected to Outdoor Weathering.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of incorporation of two compositions of nano-oxides on color stability of intrinsically colored maxillofacial silicone elastomer subjected to outdoor weathering.
  
  
  METHODS
  Ninety Cosmesil M511 silicone elastomer specimens were fabricated. The control group was incorporated with intrinsic coloring agents (umber, brown, yellow), group A was incorporated with intrinsic coloring agents and nanosized titanium oxide (TiO2), and group B was incorporated with intrinsic coloring agents and nanosized zinc oxide (ZnO). For outdoor weathering, specimens were mounted on a treated plywood rack, and the assembly was weathered for 6 months. A GretagMacbeth Spectrolino spectrophotometer was used to determine the CIELAB (L*a*b*) parameter before and after weathering of each specimen, and the values were noted. The color change (∆E) values were analyzed by one-way ANOVA, Tukey's post hoc test, and paired t-test.
  
  
  RESULTS
  The color change (ΔE*) for groups were control group > group A > group B. The control group (0.76 ± 0.32) and group A (0.47 ± 0.19) showed significant difference in the color change before and after weathering (p < 0.00001). Group B (0.03 ± 0.05) showed no significant difference in color change before and after weathering (p = 0.08).
  
  
  CONCLUSIONS
  The present findings suggest that incorporation of nano-oxides improved the color stability of Cosmesil M511 silicone elastomer and also acted as an opacifier. ZnO-incorporated Cosmesil M511 specimens showed minimal or no color change and proved to be most color stable after being subjected to outdoor weathering.
authors.affiliation: Private Practice, Pune, India.
authors.forename: R N
authors.initials: RN
authors.lastname: Akash
authors.affiliation: Department of Prosthodontics, SDM College of Dental Sciences & Hospital, Dharwad, Karnataka, India.
authors.forename: Satyabodh S
authors.initials: SS
authors.lastname: Guttal
keywords: Maxillofacial prostheses; color stability; maxillofacial silicone elastomer; nano-oxides; outdoor weathering