LOW TEMPERATURE ATMOSPHERIC PRESSURE PLASMA: A PROMISING THERAPY FOR THE FUTURE DENTISTRY

Dentistry evolved rapidly in the last decades, generating more technological and aesthetic solutions for patients, increasing the efficacy in the promotion of health and life quality. However, big challenges still persist and move the scientific community towards new solutions. Clinical conditions that lead to therapeutic failures, such as periimplantitis, refractory endodontic and periodontal infections, persistent oral candidosis, are part of clinical routine.

In particular, in the context of infectious diseases, a dark scenario comes out -a significative increase in the occurrence of antimicrobial resistance and few new molecules being discovered and effectively marketed. Besides, treating biofilm-associated diseases, such as most of the oral diseases, is challenging. Thus, in order to face these challenges, new therapeutic alternatives are needed.
The search for new alternatives points out the physical plasma. Plasma is called the "fourth state of matter" and is generated by the application of energy, such as electrical field, to a neutral gas. Cold plasma has interesting biological effects that are useful in medical area, such as antimicrobial, anti-inflammatory, anti-neoplasic effects and the ability to induce tissue repair. These biological effects are associated to plasma reactive species, such as neutral oxygen and nitrogen species (ROS and RON).
The inhibitory effects on Gram-positive and Gram-negative bacteria were reported in the literature, showing that plasma has effect on cell wall, cell membrane, and biofilm polymeric matrix. Interestingly, cold plasma showed also inhibitory effect on multi-resistant bacterial strains, increasing the interest on this technology. To the best of our knowledge, there are no reports on the development of resistance to cold plasma so far. Biofilms associated to endodontic diseases also had significant reduction in viability after treatment with cold plasma, showing higher effectiveness when compared to antimicrobial photodynamic therapy.
Interestingly, cold plasma did not show any cyto or genotoxicity to several cell lines.
Other applications in Dentistry have been suggested and should be highlighted.
The use of cold plasma in combination to low concentration of carbamide peroxide for dental bleaching showed promising results and higher preservation of dental structure when compared to standard treatment.
Lastly, the application of cold plasma to the control of malignant neoplasias has been focused by many studies in medical area and the results are exciting. An interesting study reported that cold plasma was able to inhibit the invasion of oral squamous cells carcinoma due to the reduction in the adhesion and matrix metalloproteinases activity.
There are some cold plasma devices developed and purchased in Europe, mainly focused to the use in Dermatology, and the applications in the medical area are expanding rapidly. The recent findings on cold plasma are promising and exciting and pointing out to a wide application of this technology in Future Dentistry. Kang