Photodynamic Treatment in the Management of Residual Biofilm - a Crossover Study

The antimicrobial effect of aPDT is based on the principle that light as such activates a non-toxic, photosensitive molecule, generating reactive oxygen species that kill the bacterium. Applications of aPDT in dentistry include the treatment of bacterial and fungal infections and the diagnosis of lesions. In dental treatment, regular photodynamic treatment with dual-light has been shown to be beneficial for the gingival health of dental implants and to reduce the amount of visible plaque (VPI). Photodynamic treatment has also been shown to slow down the amount of biofilm re-forming in the mouth.

The simultaneous use of blue light and near-infrared light operating at 810 nm and 405 nm has been shown to reduce Staphylococcus aureus more effectively than using only a single light source. The use of indocyanine green as a photosensitizer in dual-light phototherapy has also been shown to be effective in eliminating Streptococcus oralis. Indocyanine green has otherwise low toxicity to dental restorative materials and to non-target host tissue. Indocyanine green is also very suitable as a photosensitizer due to its high absorption peak. Indocyanine green-mediated photodynamic therapy as an adjunct to non-surgical periodontal treatment has been shown to improve treatment outcomes for dental adhesive tissue diseases with statistically significant results at 3 months and 6 months after treatment with periodontitis patients. There is in vitro evidence for the efficacy of indocyanine green specifically against periodontal pathogens.

Tooth decay, gingivitis and periodontitis are common oral infections associated with tooth extraction and are caused by bacteria living in the mouth. In total, more than 500 different species of bacteria can be found in the mouth. The normal flora of a healthy mouth is rich in a variety of microbes that start to multiply from birth.

Bacteria of different species form biofilms, or plaques (bacterial communities), on the tooth surfaces, some of which mutate to become pro-inflammatory. Most oral diseases are multifactorial. A high-sugar diet, poor oral hygiene, general diseases, dry mouth, ill-fitting dentures or antimicrobial therapy can affect the microbial balance in the mouth and thus contribute to the development of oral diseases. Locally, oral areas are affected by possible plaque overgrowth, orthodontic appliances, open caries deposits and partially erupted wisdom teeth, which provide an easy attachment site for bacterial pathogens and a challenging area to clean.

As biofilm accumulates at the gum line over several days, it causes the tissue to release inflammatory neurotransmitters that call on defense cells from the bloodstream to destroy bacteria. Inflammation of the gums appears as swelling, redness and bleeding on cleaning. If gingivitis becomes chronic, it is a risk for periodontitis, which is the inflammation and tissue destruction of the attachment tissues. Periodontitis is manifested in the mouth as inflammation of the attachment tissues, with deepening of the gum pockets around the tooth, increased tooth mobility, and alveolar leakage on X-rays.