What type of rotary instrument is used to remove a submarginal area less than 0.02mm in amalgam?

The use of a white stone in dental procedures is primarily for finishing and polishing, making it particularly effective for removing submarginal areas in materials like amalgam. When dealing with a submarginal area of less than 0.02mm, precision is vital, and white stones are designed to provide that delicate adjustment without excessively removing surrounding material.

White stones are made from an aluminum oxide abrasive, which makes them ideal for smoothening surfaces and enhancing the margins of restorations. This is particularly crucial for ensuring a good seal and optimal function in restorations. Their design allows for fine and controlled adjustments, crucial when working in tight spaces or addressing very small imperfections.

In contrast, while other instruments like diamond burs and composite finishing burs have specific uses, they are not as ideally suited for the finest adjustments required for submarginal areas in amalgam due to their more aggressive cutting abilities. Meanwhile, a slow-speed handpiece refers to the speed at which an instrument operates rather than the type of instrument used to achieve a specific result. Thus, for correcting minor imperfections in amalgam restorations, a white stone is the most appropriate choice among the options presented.