Scientists have developed a mouthwash that allows plaque-causing bacteria to be destroyed using nothing more than a bright light. It may be available for home use within three years.
The mouthwash uses "photodynamic therapy": Antibacterial molecules in the liquid are absorbed only by plaque-causing bacteria, and activated when a bright light is shone into the mouth, killing them.
The same technique is used to treat certain types of skin cancer. The substance is painted on the target area, taken up by cancer cells, then exposed to light of a certain wavelength, which activates it to kill the cancer cell.