SARS-CoV-2 in dentistry, Photodynamic therapy, PDT for SARS-CoV-2, Methylen Blue for SARSCoV- 2
In January 2020, the World Health Organization (WHO) identified a novel coronavirus SARS-CoV-2 in the Wuhan province of China, which has since caused a worldwide pandemic, with more than 21.2 million confirmed cases and over 760,200 confirmed deaths as of 14 August 2020. SARS-CoV-2 is a single-stranded RNA virus classified in the family Coronaviridae .
Various devices have been proposed for the prevention and treatment of this infections, including the use of laser and non-laser lights . If you insert the keywords “SARS CoV 2 Photodynamic therapy” on the PubMed search engine, however, you will only get 4 results, some more articles can be found with the Google Schoolar search engine. Photodynamic therapy (PDT) could be used for treatment of infections and also it is proposed in cancer and pre-cancerous lesions. Antimicrobial PDT consists mainly in the use of a photosensitizer, which binds selectively to fungal, viral, and bacterial cells, and of a light with a specific wavelength that activates it, in the presence of oxygen. For the mentioned reason it can be considered highly safe . Some studies have speculated that it may be useful in managing this pandemic, as it has already been shown its effectiveness against other influenza viruses [4,5].
A study showed that the PDT treatment of viruses induces the glycoproteins removal from the viral surface and virus become virions non-infectious, and thus without damage to the membrane .
PDT was proposed in the decontamination of products infected by microorganisms and blood, mainly in the sterilization of instruments also in surfaces contaminated by viruses such as SARS-CoV-2 .
An in vitro study evaluated the ability of methylene blue associated with blue light for 40 minutes in inactivating SARS-CoV-2, showing it to be superior to methylene blue alone or light not in combination with the dye . What is surprising about this study is that methylene blue is most frequently associated with wavelengths around 660 nm and therefore with non-blue lights . However, a study has also shown that methylene blue can be a valuable aid in the treatment of respiratory symptoms due to influenza viruses, and PDT in a broad sense could be applied in the treatment of various lung diseases, including carcinoma . As SARS-CoV-2 affects mainly the lower respiratory system, it is relatively easy to irradiate these internal organs endoscopically using an optical fiber. This can be introduced through the nose, suggesting that PDT can mediate the inactivation of the virus in the lungs . Other researchers observed that to reduce viral load, illumination of the target lung tissue using fiberoptic catheter to deliver low-power light of a characteristic absorption wavelength for the photosensitizer (typical range 450−800 nm), causes photoactivation yielding a highly reactive oxygen species capable of destroying the bonded SARS-CoV-2 virions to the photosensitizer molecules through peroxidation .
A work evaluated the use of different photosensitizers, including curcumin and vitamin B12, for release into the bloodstream, and subsequently activated by external lights. However, blue light has a poor ability to penetrate internal tissues, while wavelengths around 810 nm are the most effective . The type of photosensitizer to be used in this case would be indocyanine green, a drug already used in the medical diagnostic field .
In light of this, it must be said that however the concentration of this virus in the plasma is quite low. Red LED lights at 630 nm, at a dosage of 30 J/cm2, have proven effective against MERS CoV, Ebola virus and SARS-CoV-1 . Researchers have then highlighted how ultraviolet also have important antiviral capabilities, and among these those with a wavelength lower than 200 nm do not appear to be harmful to the skin or other body areas .
Photodynamic therapy for the treatment and prevention of this pandemic could be a valid way to go, it is important to identify the most performing parameters. It could be used to decontaminate the patient’s mouth prior to dental procedures to prevent the spread of infections.
PDT has been shown to be very useful in treating various infections in the dental field. A systematic review of the literature has highlighted its effectiveness in the periodontal, endodontic, preventive field against dental caries, and in the treatment of various pathologies of the oral mucosa including oral candidiasis . In a case report PDT showed good result in Afta major therapy .
Effectiveness in the treatment of oral HSV is documented in a recent review, most studies cited in this work used methylene blue as a photosensitizer, while one used 5-aminolevulinic acid .
Dentists are among the most at-risk categories in the medical field, and several aids such as 1% hydrogen peroxide or povidone-iodine rinses, and the use of the rubber dam, have been used to reduce the spread of the virus , but the rate of transmission in the dental office is still high . My proposal for the world of scientific research is if it could be possible combining ultraviolet light treatment, given the very easy availability, with a specific dye, to obtain a new type of photodynamic therapy, the UV-PDT in the prevention of SARS-CoV-2 spread.
2. Fernandes AB, De Lima CJ, Villaverde AG, Pereira PC, Carvalho HC, Zângaro RA. Photobiomodulation: shining light on COVID-19. Photobiomodulation, Photomedicine, and Laser Surgery. 2020 Jul 1;38(7):395-7.
3. Raizada K, Naik M. Photodynamic Therapy. In: StatPearls. Treasure Island (FL): StatPearls Publishing; July 27, 2020.
4. Queiroz GB, Foggiato AA, Neto JL, da Silva DF. Photodynamic Therapy and possible action against Sars-Cov-2. Brazilian Journal of Development. 2020 Jul 28;6(7):52313-27.
5. Weiss C, Carriere M, Fusco L, Capua I, Regla-Nava JA, Pasquali M, et al. Toward Nanotechnology-Enabled Approaches against the COVID-19 Pandemic. ACS Nano. 2020 Jun 10;14(6):6383-6406.
6. Jin C, Yu B, Zhang J, Wu H, Zhou X, Yao H, et al. Methylene blue photochemical treatment as a reliable SARS-CoV-2 plasma virus inactivation method for blood safety and convalescent plasma therapy for the COVID-19 outbreak. Research Square. 2020 Mar 17.
7. Giannelli M, Bani D. Appropriate laser wavelengths for photodynamic therapy with methylene blue. Lasers in Medical Science. 2018 Nov 1;33(8):1837-8.
8. Almeida A, Faustino MA, Neves MG. Antimicrobial Photodynamic Therapy in the Control of COVID-19. Antibiotics. 2020 Jun;9(6):320.
9. Kipshidze N, Yeo N, Kipshidze N. Photodynamic and sonodynamic therapy of acute hypoxemic respiratory failure in patients with COVID-19. Photodiagnosis and Photodynamic Therapy. 2020 Sep 1; 31:101961.
10. Fekrazad R. Photobiomodulation and antiviral photodynamic therapy as a possible novel approach in COVID-19 management. Photobiomodulation, Photomedicine, and Laser Surgery. 2020 May;38(5):255- 257.
11. Sabino CP, Sellera FP, Sales-Medina DF, Machado RR, Durigon EL, Freitas-Junior LH, Ribeiro MS. UV-C (254 nm) lethal doses for SARS-CoV-2. Photodiagnosis and Photodynamic Therapy. 2020 Sep 8.
12. Gursoy H, Ozcakir-Tomruk C, Tanalp J, Yılmaz S. Photodynamic therapy in dentistry: a literature review. Clinical Oral Investigations. 2013 May 1;17(4):1113-25.
13. Casu C, Mannu C. Atypical Afta Major Healing after Photodynamic Therapy. Case Reports in Dentistry. 2017 Jan 1;2017:8517470.
14. Lotufo MA, Horliana AC, Santana T, de Queiroz AC, Gomes AO, Motta LJ, Ferrari RA, dos Santos Fernandes KP, Bussadori SK. Efficacy of photodynamic therapy on the treatment of herpes labialis: a systematic review. Photodiagnosis and Photodynamic Therapy. 2020 Mar 1;29:101536.
15. Kochhar AS, Bhasin R, Kochhar GK, Dadlani H. COVID-19 pandemic and dental practice. International Journal of Dentistry. 2020 Jul 9;2020:8894794.
16. Zemouri C, Awad SF, Volgenant CM, Crielaard W, Laheij AM, de Soet JJ. Modeling of the transmission of coronaviruses, measles virus, influenza virus, Mycobacterium tuberculosis, and Legionella pneumophila in dental clinics. Journal of Dental Research. 2020 Sep;99(10):1192-8.