Which of the following would NOT be classified as a single-use item?

The classification of items as single-use or not is primarily determined by their intended usage and the potential risk for cross-contamination. Surgical instruments are designed for reuse; they are typically made of durable materials that can withstand sterilization processes effectively. After each use, these instruments are cleaned, sterilized, and made ready for the next patient, ensuring they are safe to use again.

On the other hand, items like disposable needles, polishing discs, and fluoride trays are intended for one-time use only, which helps to prevent any possibility of spreading infection or disease. These items are discarded immediately after their initial use to maintain a high standard of safety and hygiene in dental practices. Thus, surgical instruments stand out as the correct answer since they are explicitly intended for multiple uses, unlike the other options that are classified as single-use.