While each case is unique, the most challenging teeth to perform a root canal on are the molars, as they are located at the back of the mouth. Furthermore, molars have multiple roots and canals, making the treatment more intricate. The presence of curved or narrow canals in molars can make it challenging to effectively clean and shape them during the procedure. As the molars are positioned deep in the mouth, they are harder to access than other teeth. Additionally, if the tooth has undergone previous dental work, such as fillings or crowns, it can further complicate the root canal procedure. The removal of existing restorations and obstructions adds to the treatment complexity. However, advancements in dental technology and techniques have significantly improved the success rate of root canals, even in challenging cases.