What tool is used to loosen and tighten burs in high-speed handpieces?

The tool specifically designed to loosen and tighten burs in high-speed handpieces is known as a bur changer tool. This instrument is crafted to efficiently and safely secure or remove burs, which are essential components in dental handpieces used for cutting, shaping, or drilling teeth and other dental materials. The bur changer tool allows for a quick change of burs, which helps streamline procedures and improves the clinician's efficiency during dental treatments.

In contrast, the other instruments listed serve very different purposes in a dental setting. A plastic instrument is generally used for placing and contouring materials such as composite resins and does not have the specific function of changing burs. An articulating paper holder is used to hold articulating paper during occlusal adjustments and does not relate to handpiece operations. A matrix retainer is utilized in restorative procedures to hold a matrix band in place around a tooth but, again, does not serve the purpose of handling burs. Understanding the distinct roles of these instruments highlights the importance of using the correct tool for specific dental tasks, ensuring both efficiency and safety during procedures.