RÉSUMÉ
Objective @#To explore the discovery and treatment of multiple root canals in the maxillary second premolar to provide a reference for root canal therapy.@*Methods @#A case of maxillary second premolar occlusal discomfort accompanied by cold and heat stimulation pain and spontaneous pain was analyzed retrospectively.@*Results@# In this case, the number of roots and root canals in the tooth was determined by CBCT to be three roots with four canals. Root canal therapy was performed with Ni-Ti endodontic files and thermoplastic gutta-percha via root optical microscopy. The clinical symptoms disappeared after the operation.@*Conclusion@#The maxillary second premolar root canal system is complex, and additional root canals can be found and located with CBCT and optical microscopy. High-quality root canal therapy was completed.