Which item may not be sterilised if it is taken through a downward displacement autoclave cycle?

In a downward displacement autoclave cycle, the removal of air from the chamber is achieved by introducing steam from the top, which then flows downward. This method is effective for sterilizing many dental instruments; however, not all items are appropriate for this type of cycle.

The aspirating tip is generally made of plastic or less durable materials that may not withstand the high temperature and pressure of the autoclave process, or it may become distorted or damaged. Due to this vulnerability, it is often not suitable for sterilization in this environment.

In contrast, instruments like a burnisher, diamond bur, and luxator are typically made from metal or other materials that can endure the conditions of a downward displacement autoclave and can be adequately sterilized without undergoing any change in their physical properties. Therefore, while those items can endure the process, an aspirating tip is likely to be compromised and, as such, may not be sterilised effectively in this cycle.