A dentist needs to guide an arch wire into place. What orthodontic instrument should be used?

The wire passer is specifically designed for guiding arch wires into place during orthodontic procedures. This instrument has a tapered end that helps to easily slide the arch wire through brackets and other accessories in the mouth without causing damage to the surrounding structures, such as the gums and teeth. Its design facilitates precision and control, which is crucial when working in the tight confines of an orthodontic setup.

In contrast, separators are used to create space between teeth to allow for the placement of bands and are not suited for guiding wires. A scaler is a tool used for removing calculus from tooth surfaces and does not have the capability to manipulate arch wires. Forceps are gripping tools used for a variety of tasks, such as extracting teeth or handling materials, but they do not provide the specificity needed for guiding arch wires into place. Hence, the wire passer is the most appropriate instrument for guiding arch wires during orthodontic treatment.