What instrument is primarily used for the removal of decay during restorative procedures?

The excavator is primarily used for the removal of decay during restorative procedures because it is specifically designed to scoop out carious (decayed) tooth structure. Its spoon-shaped design allows for precise and controlled removal of soft, decayed dentin, ensuring that all affected areas are eliminated to make way for restorative materials. The excavator's blade can vary in size and shape, allowing it to reach different areas of the tooth effectively.

In contrast, an explorer is typically used for detecting caries and checking the health of the tooth surface, but it does not have the same capability for material removal as the excavator. A scalpel is intended for cutting soft tissue and has no application in removing dental decay. A defibrillator is a medical device used in emergencies to restore normal heartbeat and is not related to dental procedures. Thus, the excavator is the appropriate instrument for this specific restorative function.