Effect of bisoctrizole addition on color stability after artificial aging and surface hardness of scleral acrylic resin: an in-vitro study

The color degradation of ocular prostheses is significantly affected by exposure to ultraviolet (UV) light over time. As a result, the prosthesis requires frequent replacement, ultimately increases the financial burden of rehabilitation on the patient. This study aimed to determine the optimal bisoctrizole percentage for ocular acrylic by assessing its effects on color stability after 300 h of artificial aging and on surface hardness. A total of 120 specimens were prepared from white heat-cure scleral acrylic and subdivided into two groups according to the conducted tests; color stability and surface hardness. Each of these groups were further subdivided into 6 groups with 10 specimens for each based on the weight percentages of bisoctrizole added; 0%, 0.5%, 1%, 1.5%, 2% and 2.5%. The color parameters were measured before and after artificial weathering using a portable digital colorimeter according to the CIE L*a*b* system. Shapiro-Wilk test was used to confirm normality of data. One-way ANOVA was used among the study groups followed by Tukey's honestly significant difference (HSD) as a post hoc test (α = 0.05). All groups exhibited significant (p < 0.001) color change (ΔE > 0) after aging, with the control (0%) showing the highest ΔE. A progressive decrease in ΔE was observed with increasing bisoctrizole. Surface hardness was clinically comparable, though compared to the control, a statistically significant difference was found in Groups 1.5% and 2% (p < 0.001). Bisoctrizole had effectively preserved the color of scleral acrylic over time under UV light. Additionally, it had minimally affected the surface hardness of the material.