Photodynamic therapy in endodontics for endodontic decontamination.
Video demonstrating the protocol for using photodynamic therapy for decontamination during endodontic treatment.
In: Amaral et. al. Photodynamic therapy in endodontics - literature review. RFO UPF vol.15 no.2 Passo Fundo May/Aug. 2010
Introduction
In recent decades, endodontics has evolved substantially with the development and adoption of new technologies and materials, facilitating the work of the endodontist and reducing the time for performing endodontic treatment. Despite this, most failures or endodontic failures are related to the persistence of microorganisms that resisted chemical-mechanical preparation or intracanal medication¹.
The photodynamic therapy emerges as a new therapy, adjuvant to endodontic treatment, in an attempt to eliminate persistent microorganisms to the chemical-mechanical preparation. Being of easy and fast clinical application, it does not develop microbial resistance, and can be indicated in endodontic treatments in single or multiple sessions.
This article aims to review the literature on the use of photodynamic therapy in endodontics. History The use of light as a therapeutic agent has been used in the treatment of diseases since ancient times. In Egypt, India and China, sunlight was used to treat skin diseases such as psoriasis, vitiligo and cancer. The Greek physician Herodotus emphasized the importance of sunlight exposure for the restoration of health². The concept of cell death induced by the interaction of light and chemicals has been recognized for more than a hundred years. In the year 1900, the first experiments with photodynamic treatment were reported by Oscar Raab, a medical student, and his professor, Herman Von Tappeiner, in Munich. They studied the effect of acridine dye on paramecium cultures and found that the combination of acridine dye and light was lethal for them.
During a lightning storm there was a change in the light conditions of the environment at the time of the experiments, which led the authors to postulate that this effect was caused by the transfer of light energy to chemical substance, similar to what occurs in plants through the absorption of light by chlorophyll. Neither the light nor the dye alone had any apparent effect on the parameciums, but together they were highly cytotoxic²,³.
Mechanism of interaction Photodynamic therapy, also known as PDT, an acronym for photodynamic therapy, has emerged as a promising antimicrobial therapy. It involves the use of a photosensitizer (dye), which is activated by light of a specific wavelength in the presence of oxygen. The transfer of energy from the activated photosensitizer to the available oxygen results in the formation of toxic oxygen species, known as singletet oxygen and free radicals.
These are highly reactive chemical specimens that damage proteins, lipids, nucleic acids and other microbial cellular components4. It is important that the light source is absorbed by the dye in order for PDT to be effective in making cells inviable². Most oral bacteria do not absorb visible light from lasers operating at low power, with the exception of some Gram-positive microorganisms, Actinomyces odontolyticus and Porphyromonas gingivalis, which synthesize endogenous porphyrins5. The use of a non-toxic optical absorption agent that attaches to the bacterial cell wall and attracts the laser light is necessary for the antimicrobial action on oral bacteria.
According to Machado6 (2000), the reaction involved arises, primarily, from the electronic excitation of the dye by the light, followed by two main reaction mechanisms from its excited state. In the type I reaction there is electron transfer between the photosensitizer, in the triplet excited state, and components of the system, generating radical ions, which tend to react with oxygen in the fundamental state, resulting in oxidized products, such as hydrogen peroxide, hydroxyl ions, hydroxyl radicals, and superoxide anion, which are toxic to microorganisms. In the type II reaction occurs the transfer of energy from the photosensitizer in the triplet state, with the generation of singlet oxygen, a highly cytotoxic agent. The ability of the molecule to form redox reaction or singlet oxygen depends on the sufficient production of molecules in the triplet state, which in turn depends on the rate of decay of both triplet and singlet states initially formed7. Photodynamic therapy in endodontics
https://ferrariendodontia.com.br/terapia-fotodinamica-na-endodontia/
