Laser-Assisted Root Canal Therapy Lasers essentially emit intense focused light energy, the particular properties of which can interact with biologic tissues. Lasers can now be used to open the surface of a tooth to access the root canal, remove diseased tissue, clean, disinfect and shape the canal, and fill it. Is laser RCT painful? As a relatively common yet painful dental procedure, it's no wonder that patients fear it. ... In fact, Waterlase dental lasers are indicated for cleaning and shaping of root canals and for laser root canal disinfection after endodontic treatment.