Which instrument is used to curette the inside of a tooth to the pulp chamber's base?

The long-shank spoon is specifically designed for removing debris and decay from the inside of a tooth, particularly when accessing the pulp chamber. This instrument has a rounded, scooping end that allows for effective scraping and removal of materials from the walls of the cavity, leading down to the base of the pulp chamber. Its design provides the necessary reach and control, making it ideal for delicate procedures involved in preparing a tooth for root canal treatment or other restorative work.

In contrast to the long-shank spoon, instruments such as the reamer, file, and explorer serve different purposes. A reamer is primarily used for enlarging the canal space within a tooth during endodontic procedures, while files are utilized for shaping and cleaning the canal. The explorer is designed to detect cavities and check the integrity of a tooth's surface. Thus, the long-shank spoon's design and function make it the most appropriate choice for curetting the tooth to reach the base of the pulp chamber effectively.