For more information and the complete article about blue light therapy and dental health, read Light Blitzes Plaque from Harvard Magazine
"Associate clinical professor of periodontal medicine J. Max Goodson, the institute’s director of clinical research, was using intense blue light (its wavelength falling within the blue segment of the visible light spectrum) to whiten patients’ teeth, the same way sunlight bleaches laundry hanging in a backyard. Because he expected the light to cause a sunburn-like reaction as a side effect, he measured the inflammation of the patients’ gums. “Much to our surprise,” he says, “rather than an irritating effect, we actually found a diminution of inflammation.”
|One prototype of a blue-light-emitting device proposed by Harvard researchers resembles an electric toothbrush. Using it inside the mouth for 30 seconds daily might help prevent much periodontal disease.
|Photograph by Jim Harrison
Goodson had stumbled on a discovery with important implications for preventing and treating periodontal disease, which affects 30 percent of Americans to a degree that threatens tooth loss. After a single one-hour treatment with blue light, patients’ gingival index scores—which measure inflammation, a symptom of gum disease—not only dropped, but stayed down for six months. On a scale of zero (normal, healthy gums) to three (spontaneous bleeding, without any probing), the average patient’s score went from 0.64 before the whitening treatment to 0.33 three months later, and 0.28 six months later.
Upon reflection, the finding made sense. Several species of bacteria that cause periodontal disease, known as black-pigmented bacteria, transport hemoglobin into their bodies as an iron source (this is thought to be why they make the gums bleed, by using enzymes that weaken blood vessels), and store the hemoglobin’s dark-colored, photosensitive porphyrin. Light directed at these bacteria is absorbed by the porphyrin and, through a chemical reaction, produces substances that are toxic within the bacterial cell.
💙 Because the whitening treatment used peroxide, an antibiotic, as well as light, Goodson—working with instructor in dermatology Nikolaos S. Soukos, who directs the Forsyth Institute’s applied molecular photomedicine lab—tested the finding using light alone. Their results, reported recently in Antimicrobial Agents and Chemotherapy, showed that in the mouths of control-group members, who were told they were receiving light therapy, black-pigmented bacteria constituted 6 percent of all oral bacteria. In the mouths of people who received the blue-light treatment, just 1 percent of the bacteria were black-pigmented. (The researchers’ goal is not to banish all bacteria from the mouth, but to get rid of the most harmful types—Soukos speaks of restoring “balance and harmony in dental plaque.”) Goodson and Soukos also experimented with other colors of light and found that blue worked best. At this point, they aren’t sure why."