Which instrument is often required to visualize and access the canal system?

The endo explorer is specifically designed for endodontic procedures, particularly for locating and accessing the canal system of a tooth. Its thin, pointed tip allows dental professionals to navigate through the intricate anatomy of the root canals, including finding canal orifices and assessing the condition of the tissue within the canals. This capability is essential for thorough cleaning and shaping during root canal therapy.

In contrast, other instruments on the list serve different purposes. The straight fissure bur is utilized for cutting enamel and dentin, shaping and preparing cavities but is not designed for accessing canal systems. The Glick instrument is primarily used for the placement and removal of temporary restorations and for carrying material into the canal but does not assist significantly in visualizing the canal itself. The irrigating syringe is important for delivering solutions to cleanse the canal but does not aid in visualizing or gaining access to the canal system. Thus, the endo explorer is the correct choice as it plays a pivotal role in accessing and visualizing the internal anatomy of the tooth during endodontic treatments.