Abstract: System and method for non-invasive sonication, through at least one of enamel and dentin, of a root-canal system of a target tooth with an externally delivered ultrasound beam, to disinfect the root-canal system while blocking a nerve associated with the tooth and removing a need for radiography to confirm the results of endodontics. The tooth does not have a physical access opening to the root canal system. When focused, the beam is oriented to expose the root-canal system to the ultrasound within the confocal range of the beam such as to concentrate the ultrasound energy within the root-canal system and to avoid irradiating teeth that are immediately adjacent to the target tooth.