Which of the following is NOT used in administering anesthesia in dentistry?

The correct choice is the diamond bur, as it is a dental instrument primarily used for cutting hard tissues, such as enamel and dentin, during restorative procedures or cavity preparations. It is not involved in the administration of anesthesia.

Topical anesthesia, anesthetic aspirating syringes, and needles, on the other hand, are directly related to the process of delivering anesthesia. Topical anesthesia is applied to mucosal surfaces to numb the area before injections are made. Anesthetic aspirating syringes are designed to hold anesthetic solutions while allowing the clinician to aspirate, or check for blood return, ensuring that the needle is not inadvertently placed in a blood vessel. Needles are essential for delivering local anesthesia into the tissues. Thus, the diamond bur stands apart as it serves an entirely different purpose in dental procedures.