Plasma can be used to combat oral biofilm

Research into the use of ionized gas to destroy bacteria that cause infections in teeth and gums has been chosen to represent Brazil at the annual meeting of the International Association for Dental Research.

By José Tadeu Arantes

Agência FAPESP – Low-temperature plasma obtained by ionizing argon gas may become an alternative for the removal of pathogenic oral biofilm, which is composed of a community of unhealthy bacteria that can cause infections in teeth and gum tissue as well as in implants.

The procedure has been shown to be effective against microorganisms in applications lasting only a few seconds, making it innovative compared with conventional therapies.

Research on this subject developed by Juliana Aparecida Delben, a postdoctoral researcher at the Araraquara Dental School of Universidade Estadual Paulista (UNESP), has won an award from the Brazilian Dental Research Society (Sociedade Brasileira de Pesquisa Odontológica) and has been selected as one of two research projects that will represent Brazil at the annual meeting of the International Association for Dental Research (IADR) in Boston, Massachusetts, in March 2015. Delben’s postdoctoral research is supported by FAPESP.

“In the lab, we grew biofilm on an acrylic resin disc to simulate the development of the aggregate of microorganisms in the oral cavity. This model is well established in the literature. The same dose of plasma was then applied to oral epithelium reconstituted in the lab using human cells, with the aim of testing the toxicity of the procedure,” Delben told Agência FAPESP.

The procedure was shown to be effective in combating mature biofilm that is resistant to eradication using antibiotics. At the same time, the tests using reconstituted epithelium showed no signs of necrosis (cell death) or apoptosis (controlled cellular self-destruction). “Both cells and cell functions remained intact,” said Delben. The plasma used was obtained by ionizing argon gas to produce ions, free radicals, electrons and electromagnetic radiation, an effective combination of agents to combat bacteria and fungi.

“Furthermore, the application of plasma leads to the formation of reactive forms of oxygen inside the biofilm, which probably cause damage to the microorganisms’ DNA and rupture their protective structure. A significant number of the bacteria are eliminated as a result,” Delben explained.

This type of plasma is already used in dermatology to treat chronic skin wounds that fail to heal because of bacterial contamination. In some dermatological applications, plasma has been found to stimulate the multiplication of healthy cells, favoring tissue regeneration while eliminating biofilm. However, the possibility of cell mutation during the multiplication process must be investigated in order for the procedure to be considered completely safe.

This investigation is one of the next steps designed by Delben. Her research was supervised by Carlos Eduardo Vergani, Full Professor, Araraquara Dental School, UNESP, with collaboration from Simone Duarte, a researcher at New York University and Delben’s supervisor during an internship at NYU.