Laser as an Accessory Treatment in Dentistry: A Narrative Review on Its Efficacy in Complex Root Canal System Infections, Pain Control, and Dental Tissue Regeneration

Conventional root canal therapy relies on mechanical instrumentation and chemical irrigation; however, the complex anatomy of the root canal system often compromises complete disinfection, particularly of anaerobic bacterial biofilms, resulting in persistent or recurrent infections. Laser-assisted endodontic therapy has emerged as an effective adjunct, enhancing antimicrobial efficacy through photothermal effects, photodynamic action, and cavitation, thereby improving disinfection in anatomically inaccessible regions. In addition, laser therapy has been shown to stimulate stem cell proliferation, modulate inflammatory responses, reduce postoperative pain, and promote apical tissue regeneratiojn. Currently, Er:YAG, diode, Nd:YAG, and CO 2 lasers are widely used for refractory infection control, smear layer removal, and dentin hypersensitivity reduction. Moreover, laser–nanoparticle interactions further enhance antibacterial efficacy. This narrative review summarizes the applications of laser technology in root canal disinfection, pulp regeneration, and pain management, providing a scientific and clinical basis for the treatment of persistent fistulas and refractory root canal infections.