Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

Abstract

Antimicrobial photodynamic therapy (APDT) has gained increased attention as an alternative treatment approach in various medical fields. However, the effect of APDT using visible light plus water-filtered infrared A (VIS ؉ wIRA) on oral biofilms remains unexplored. For this purpose, initial and mature oral biofilms were obtained in situ; six healthy subjects wore individual upper jaw acrylic devices with bovine enamel slabs attached to their proximal sites for 2 h or 3 days. The biofilms were incubated with 100 g ml ؊1 toluidine blue O (TB) or chlorin e6 (Ce6) and irradiated with VIS ؉ wIRA with an energy density of 200 mW cm ؊2 for 5 min. After cultivation, the CFU of half of the treated biofilm samples were quantified, whereas following live/dead staining, the other half of the samples were monitored by confocal laser scanning microscopy (CLSM). TB-and Ce6-mediated APDT yielded a significant decrease of up to 3.8 and 5.7 log 10 CFU for initial and mature oral biofilms, respectively. Quantification of the stained photoinactivated microorganisms confirmed these results. Overall, CLSM revealed the diffusion of the tested photosensitizers into the deepest biofilm layers after exposure to APDT. In particular, Ce6-aided APDT presented elevated permeability and higher effectiveness in eradicating 89.62% of biofilm bacteria compared to TB-aided APDT (82.25%) after 3 days. In conclusion, antimicrobial photoinactivation using VIS ؉ wIRA proved highly potent in eradicating oral biofilms. Since APDT excludes the development of microbial resistance, it could supplement the pharmaceutical treatment of periodontitis or peri-implantitis.

Photoinactivation Using Visible Light Plus Water-Filtered Infrared-A (vis+wIRA) and Chlorine e6 (Ce6) Eradicates Planktonic Periodontal Pathogens and Subgingival Biofilms

“…A broad-band vis+wIRA radiator (Hydrosun 750 FS, Hydrosun Medizintechnik, Müllheim Germany) with a 7 mm water cuvette was used as described previously (Al-Ahmad et al, 2013a, 2015; Karygianni et al, 2014). An orange filter, BTE31, which provides more than twice the effective integral irradiance with regard to the absorption spectrum of protoporphyrin IX was fitted to the device.…”

“…To quantify the live and dead bacteria within the subgingival biofilm samples, the fluorescent SYTO ® 9 stain and propidium iodide (PI) assay (Live/Dead ® BacLight TM Bacterial Viability Kit, Life Technologies GmbH, Darmstadt, Germany) was applied as described earlier in detail (Karygianni et al, 2014). In brief, both fluorescent agents were diluted in a 0.9% NaCl solution to a final concentration of 0.1 nmol ml -1 .…”

“…Due to the increasingly widespread number of resistant microorganisms, intense interest has been generated about alternative treatment methods such as antimicrobial photodynamic therapy (aPDT; Cieplik et al, 2014; Karygianni et al, 2014; Al-Ahmad et al, 2015). The mechanism of aPDT action involves numerous structural and functional inactivations of microbial cells in parallel, making development of resistance against the photodynamic inactivation process much harder to be developed (Wainwright et al, 2010).…”

“…In addition, wIRA decreases thermal stress and protects external tissue layers, mainly due to its significant subcutaneous tissue penetration (Jung and Grune, 2012; Kunzli et al, 2013). In our own studies, aPDT using vis and wIRA in combination with the photosensitizer chlorine e6 (Ce6), a chlorophyll “a”-based second-generation photosensitizing agent derived from the green seawater algae Chlorella ( Chlorella ellipsoidea ) (Park et al, 2012), exhibited high antimicrobial activity against Streptococcus mutans , Enterococcus faecalis , and the in situ formed initial and mature supragingival biofilm (Al-Ahmad et al, 2013a; Karygianni et al, 2014). Furthermore, the microbial composition of the in situ oral supragingival biofilm was substantially altered after aPDT (vis+wIRA) when combined with Ce6 (Al-Ahmad et al, 2015).…”

A eficácia da terapia fotodinâmica no tratamento periodontal não cirúrgico

“…Diversos estudos in vitro tem comprovado alta taxa de destruição de microrganismos submetidos à terapia fotodinâmica 17 . A PDT usando visible light plus waterfiltered infrared-A wavelengths (VIS e wIRA) em combinação com o fotossensibilizador cloro e6 (Ce6), exibiram alta atividade antimicrobiana contra Streptococcus mutans, Enterococcus faecalis e o biofilme supragengival formado 18 . Além de comprovar que a ação bactericida foi maior quando laser e fotossensiblizador foram aplicados conjuntamente 19 , estudos evidenciaram a interferência do comprimento de onda dos lasers nos resultados obtidos.…”