Bactericidal effects of different laser wavelengths on periodontopathic germs in photodynamic therapy

Abstract

This study was an attempt to clarify whether the bactericidal effects of photodynamic therapy (PDT) are wavelength or dose-dependent. We also attempted to create an optimised protocol for a light-based bactericidal modality to eliminate periodontal pathogens. Cultures of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphromonas gingivalis, Prevotella intermedia, and Streptococcus sanguis, were exposed to a He-Ne laser (632.8 nm) with a 30 mW power output, a 100 mW diode laser at 665 nm, or a 100 mW diode laser at 830 nm, in the presence or absence of methylene blue (MB) as a photosensitiser. A control group was also used with exposure to MB alone without laser exposure. The cultures were analysed by viable counts. The results indicated that exposure to the 100 mW laser light could eliminate up to 40% of bacteria on average. In particular, the most effective killing occurred with exposure to laser light in combination with the MB photosensitiser. The results of kinetic studies indicated that the best PDT response rate was achieved with a 60 s (energy density 21.2 J/cm(2)) exposure to the 665 nm wavelength diode laser in the presence photosensitiser. In this condition, approximately 95% of A. actinomycetemcomitans and F. nucleatum, and 99-100% of the black-pigmented bacteria ( P. gingivalis and P. intermedia) and S. sanguis were eliminated. These results showed that both wavelength and energy density are important factors, and that a low power laser of optimal wavelength and dosage, in combination with an appropriate photosensitiser, is a practical bactericidal modality. We concluded that using a diode laser of proper power and wavelength to deliver 60 s of irradiation could be a useful adjunct with mechanical debridement in the prevention of the re-colonisation of subgingival lesions by pathogenic microorganisms.

The Effect of Photodynamic Therapy in the Treatment of Chronic Periodontitis: A Review of Literature

“…Although in most of these studies, laser diode has been used, but none of them mentioned which types of laser, photosensitizer, wavelength, power and intensity are more effective. 29 It appears that the use of multiple doses of laser is more effective than only one dose. 30 But only 1 of the 5 studies shows that using laser results positively in improving clinical parameters.…”

Low Level Laser Applications in Periodontology

“…, In this review, benefits, limitations and the use of LLLT in various areas of periodontal therapy are discussed in the light of the literature. Key words: Low level laser therapy, periodontal treatment MÜSBED 2014;4(1): [43][44][45][46][47][48][49][50] Derleme / Review GİRİŞ ''Light Amplification by Stimulated Emission of Radiation'' kelimelerinin ilk harflerinden oluşturulan LASER terimi, dilimize LAZER olarak girmiş, 'radyasyonun uyarılmış emisyonu ile ışığın güçlendirilmesi' anlamına gelmektedir. Tıpta ilk kez 1962 yılında dermatolog Goldman tarafından kullanılan lazer, 1963 yılında oftalmolojistlerin kullanması ile çeşitli dallarda uygulanmaya başlanmıştır.…”

Photo-bactericidal Properties of Hydroxyapatite Implant Surface Coating

“…Currently the most promising methods to achieve the bactericidal effect are physical methods particularly antimicrobial photodynamic therapy [33][34][35][36][37][38]. This method shows a pronounced photo bactericidal activity, anti-inflammatory effect and has gained more attention owing to its broad-spectrum antibacterial properties at very low concentrations, good biocompatibility, satisfactory safety profile, and inherent stability.…”