The mouth houses the second most diverse microbial community in the body – referred to as our ORAL MICROBIOME - after the gastrointestinal tract, harboring over 700 species of bacteria. These microorganisms form groups known as biofilms that stick to teeth (dental plaque), gums, tongue and other mucous membranes in the oral cavity. Twenty billion bacteria live in our mouth at any given time. Every day we swallow 100 billion microorganisms. Harmful bacteria are a minority (usually < 5%).


Dental plaque (biofilm) grows on tooth surfaces and can cause gum disease (A). Dental plaque and other oral biofilms are highly complex structural entities consisting of bacteria and their products embedded in a slimy matrix (B). 90% of adults have gum disease with signs ranging with swollen and bleeding gums (gingivitis, C) to receding gums and loose teeth (periodontitis, D). Biofilms form a white coating on the tongue (E), where bacteria create odors of bad breath (halitosis).


In health, the ORAL MICROBIOME maintains its natural diversity and the composition of microbial communities is stable (symbiosis). Increased risk of disease occurs when the natural balance of our oral microbiome is disrupted with one or several potentially-pathogenic bacteria growing to markedly higher proportions (dysbiosis). For instance, dysbiotic dental plaque will initially induce gingivitis followed by periodontitis with destruction of periodontal tissues. Dysbiosis can also cause bacteremia that facilitates dissemination of pathogenic bacteria that have been linked with a number of systemic diseases, such as cardiovas­cular disease and stroke, inflammatory bowel disease, diabetes, pneumonia, rheumatoid arthritis, colorectal cancer, and adverse pregnancy outcomes. Therefore, promoting a balanced microbiome is important for both oral and systemic health.


The conventional practice and treatment is to brush teeth and then rinse the mouth with a strong antibacterial cleaner killing ALL bacteria (pathogenic and non-pathogenic), thus disrupting the oral ecosystem balance with detrimental consequences for our oral and general health. Antiseptics disrupt the balance thereby creating a pathology for opportunistic infections, alter the gut microflora, and produce unpleasant side effects. 


Our Discovery

As published in the April 7, 2005 Harvard Gazette, the two inventors and founders of Photomedics, Drs. Nikos Soukos and J. Max Goodson, introduced at the Harvard-affiliated Forsyth Institute what we call the "Achilles Heel” of key potentially-pathogenic bacteria (black-pigmented bacteria) in dental plaque (2002). This Achilles Heel is known as porphyrins – organic compounds produced and accumulated within pathogenic bacteria that are highly sensitive to blue light. Upon activation of porphyrins by blue light, toxic substances are formed that kill bacteria.


Black-pigmented bacteria (arrows) grown on agar plate obtained from human dental plaque samples (A). These microorganisms produce and accumulate endogenous porphyrins that are photosensitive (B).


Upon activation of porphyrins by blue light, toxic substances are formed that kill bacteria. Briefly, porphyrins in pathogenic bacteria absorb blue light energy that is transferred to Molecular Oxygen to produce excited state Singlet Oxygen (see details below), which oxidizes the biological molecules of the bacteria and leads to bacterial cell death.

By suppressing potentially-pathogenic bacteria in dental plaque and other areas of the mouth using blue light, our goal is to increase the proportion of good bacteria thus restoring and maintaining balance (homeostasis) among oral microorganisms. 

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Click any of the titles below to download the RESPECTIVE paper.

Click any of the titles below to download the RESPECTIVE paper.

Visible Spectrum Light Selectively Kills Black-pigmented Bacteria of Human Dental Plaque (2003)
Soukos Nikolaos, Som Sovanda, Goodson JM.
IADR/PER General Session (Goteborg, Sweden)

Phototargeting Oral Black-Pigmented Bacteria (2005)
NS Soukos, S Som, AD Abernethy, K Ruggiero, J Dunham, C Lee, AG Doukas, JM Goodson
Antimicrobial Agents and Chemotherapy 49 (4), 1391-1396.

Photodynamic Therapy in the Control of Oral Biofilms (2011)
NS Soukos, JM Goodson
Periodontology 2000 55 (1), 143-166.

The Effect of Blue Light on Periodontal Biofilm Growth in Vitro (2015)
CR Fontana, X Song, A Polymeri, JM Goodson, X Wang, NS Soukos
Lasers in Medical Science 30 (8), 2077-2086.

Phototargeting Human Periodontal Pathogens In Vivo (2015)
NS Soukos, J Stultz, AD Abernethy, JM Goodson
Lasers in Medical Science 30 (3), 943-952.