Which of the following cannot be disinfected or reused?

The orangewood stick cannot be disinfected or reused because it is a wooden implement. Wood is porous, meaning it can harbor bacteria and pathogens within its tiny fibers, making it impossible to thoroughly disinfect. Once used, the integrity of the wooden stick can also be compromised, which further increases the risk of contamination.

In comparison, the plastic manicure brush, metal pusher, and nippers are made from materials that can withstand the processes of cleaning and disinfection. These tools can be sterilized effectively, ensuring that any harmful microorganisms are eliminated before they are reused on another client. Proper sanitation practices dictate that only tools that can be effectively disinfected should be reused, which is why the wooden orangewood stick is not suitable for such purposes.