What is the common cause of high pH surface deposits that lead to staining?

• A. Chlorhexidine usage
• B. Metal corrosion
• C. Exposure to sunlight
• D. Excessive humidity

Answer: (A)

High pH surface deposits that lead to staining are most commonly associated with the usage of chlorhexidine. Chlorhexidine is an antiseptic that is frequently used in surgical settings for skin disinfection and hand-washing. When it comes into contact with metal instruments, it can leave a residue that, when exposed to air, can lead to an increase in pH on the surface of those instruments. This higher pH can promote the formation of deposits that can stain the instruments over time.

While other factors like metal corrosion, exposure to sunlight, and excessive humidity can contribute to staining or degradation of instruments, they do not primarily result in high pH conditions as a direct consequence. Instead, they might lead to other types of surface issues or degradation due to environmental stressors or chemical reactions. Therefore, the significant role of chlorhexidine in creating high pH surface deposits makes it the most relevant answer in this context.