|Year : 2016 | Volume
| Issue : 1 | Page : 81-83
Cold plasma: Northern lights in the dental office: A brief review
Neha Sisodia1, Mysore Krishnaswamy Manjunath2
1 Department of Dentistry, Post Graduate Institute of Medical Education and Research (PGIMER), Dr. Ram Manohar Lohia Hospital, New Delhi, India
2 Department of Conservative Dentistry and Endodontics, JSS Dental College and Hospital, Mysore, Karnataka, India
|Date of Web Publication||12-Feb-2016|
Dr. Neha Sisodia
Post Graduate Institute of Medical Education and Research (PGIMER), Dr. Ram Manohar Lohia Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Plasma is often called the "fourth state of matter." Its plentiful supply in the nature coupled with its potential antibacterial properties made it a widely used disinfectant in medical sciences. Research on this gas has highlighted its ability to provide pain-free disinfection of even pits and fissures of the occlusal surface of the tooth. This heralded the development of newer devices, such as plasma needle and plasma pen, that are being increasingly used in the field of dental sciences. Increased on-demand esthetic procedures, such as bleaching, are currently in vogue. The ability of free radicals to activate bleaching agents has prompted their use in the esthetic dentistry. Plasma also has the potential to alter surface energy of a substrate prompting its use in different areas of dentistry from restoration of teeth to their replacement with implants.
Keywords: Nonthermal atmospheric plasma, plasma arc curing (PAC), plasma needle, prions
|How to cite this article:|
Sisodia N, Manjunath MK. Cold plasma: Northern lights in the dental office: A brief review. J Int Clin Dent Res Organ 2016;8:81-3
|How to cite this URL:|
Sisodia N, Manjunath MK. Cold plasma: Northern lights in the dental office: A brief review. J Int Clin Dent Res Organ [serial online] 2016 [cited 2020 Oct 27];8:81-3. Available from: https://www.jicdro.org/text.asp?2016/8/1/81/176263
| Introduction|| |
Plasma is defined as a gas containing free electrons, ions, and various other active atomic or molecular radicals such as hydroxyl radicals (OH).  It is believed to be the most common form of matter, making up more than 99% of the visible universe. From neon signs to fluorescent lights, plasma energy has been harnessed by man to meet his everyday requirements.
Based on the relative temperatures of the electrons, ions, and neutrals, plasmas are classified as "thermal" (hot) and "nonthermal" (cold).  Hot plasma techniques in the form of electrosurgery and coagulation have been used in medical sciences for a long time to achieve hemostasis.
The term "cold plasma" was coined by Ivan Langmuir in 1929 to describe plasma generated at low temperature (below 40°C). Its use in dentistry has been postulated due to its ability to enter into the narrow, constricted spaces and disinfect them, its property of increasing the surface energy of a substrate, thus enhancing wettability and bonding without any potential for charring. A recent study has conclusively shown the ability of nonthermal plasma to effectively eliminate both gram-negative and gram-positive microbes such as Enterococcus faecalis. 
The development of nonthermal atmospheric plasma that permitted surface preparation in open air at room temperature for biomedical applications culminated in the production of various devices for biomedical applications such as the radio frequency dielectric barrier discharge(RF DBD) by Stoffels et al. or the dielectric barrier discharge (DBD) pulsed by Laroussi and Lu. 
One of the most well-known plasma-based biomedical devices is the handheld plasma needle. This refers to a capacitively coupled radiofrequency discharge, generated at the tip of a sharp needle. A 5-cm long tungsten electrode is placed in a Perspex tube, powered at a radiofrequency of 13.56 MHz, forming the body of the needle. It is supplied with a He/O 2 (20%) air mixture at a flow rate of 0-21 L/min. The beam is concentrated at a small volume 1 mm 3 , allowing for greater precision , [Figure 1]. Plasma, produced through this device, is said to be ultraconservative and bactericidal, and it provides painless disinfection. These properties are subject to variables such as the distance from the needle to the object (an ideal distance of 1-2 mm allows for a focused beam and the feed gas composition (the most commonly used composition is a He-O 2 air mixture). The correct gas mixture is required to ensure that the two gases do not negate each other and render formation of plasma impossible. 
Later, various modified forms of the original plasma needle, such as the "plasma pen," were introduced.  Wherein a metal electrode (0.3 mm) is selected and placed in a Perspex tube having an internal diameter of 0.8 mm, and powered at 13.56 MHz. The efficacy of this modification for elimination of bacteria within the root canal has been extensively studied. More recently, scientists have attempted to ascertain the role of plasma in conservative cavity preparation by the development of a miniature atmospheric cold plasma brush. 
Cold plasma has great potential for use in dentistry as it is vibration-free, leading to lesser pain perception by the patient. It is especially helpful in dealing with patients suffering from anxiety and fear of the drill use for cavity preparation prior to the restoration of teeth and removal of necrotic, infected, and non-remineralizable tissues.
A recent study demonstrated that plasma at 220 mV causes a rise in temperature of less than 2.3°C, causing no thermal damage to the pulp tissue. It does not denature biological tissues as it acts under the threshold of thermal damage of soft tissues unlike hot plasma.
Its role in wound healing is postulated due to its ability to generate free radicals well within the physiologic range of the body during natural tissue repair, allowing for higher cell turnover rate.
Its disinfectant property is said to be effective against biofilms and against tenacious microbes such as Escherichia More Details coli. The mechanism of action at cellular level is believed to be twofold via either cell detachment (specificity targets cadherins) or cell death (production of reactive oxygen species). Zhang recently reported on the use of plasma plume (a modification of needle funnel at tip) for inactivation of Streptococcus mutans. Lu et al. reported on the development of a reliable, user-friendly "plasma jet" device for use within the root canal. This could be touched with bare hands and directed into the root canal for adequate disinfection. 
The material of choice for in-office bleaching remains peroxide, whether being laser-assisted or not. A recent study compared cold "plasma microjet" with H 2 O 2 using a sagittal split study model. Studies report a three times better result with the use of plasma when compared to power bleaching. No reduction in microhardness was reported in the scanning electron microscopic image. 
The use of plasma arc curing (PAC) units for curing direct resin composite is associated with a shorter cure time, but is also associated with increased amount of development of residual stresses and increased polymerization shrinkage. Plasma treatment increases the number of free radicals and ions on tooth substrate creating increased bond strength. A reported increase in durability and longevity of the bond (due to removal of smear layer and better exposure of type I collagen fibers) has made its use more attractive. 
Plasma-sprayed hydroxyapatite-coated dental implants have revolutionized the field of implantology, providing better osseointegration and more reliable results and making the process of replacing teeth with implants a treatment of choice for dental problems with a high success rate.
Another area of increased patient and clinician awareness is achieving adequate sterilization and disinfection in the dental office. The use of sharp objects in dentistry, coupled with close contact of equipment with blood and saliva, has led to increase the need for adequate sterilization of instruments before reuse and disposal. Irregular contact with the endodontic files at different areas, when heat is used, leads to an inadequate sterilization. Another area of concern, not addressed by conventional means of sterilization and disinfection is the presence of prions. These heat-resistant protein particles have been associated with diseases such as acquired Creutzfeldt-Jacob disease. The role of surgical instrument in transmission of prions is well established. Endodontic files may also act as a potential source of iatrogenic transmission of the same, as these organisms show high surface affinity for organic material, which persists within the flutes. A recent study demonstrated that approximately 50-µm thick organic matter persisted on flutes of file after endodontic procedures allowing for propogation of prions. It is considered an excellent technique for elimination of organic material from surface of the instrument, this allows for a solvent free removal of organic debris with added advantage of production of by-products such as CO 2 and H 2 O rather than dangerous by-products associated with use of chemical agents such as alkylating agents. 
| Conclusion|| |
This noiseless, painless ultraconservative technique is bound to herald the future of dentistry, with its powerful healing effect, noninvasive nature, and bactericidal properties. While certain technical glitches must be sorted out before its application in clinical practice, it holds tremendous promise of revolutionizing dental procedures.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Sladek RE, Stoffels E, Walraven R, Tielbeek PJ, Koolhoven RA. Plasma treatment of dental cavities: A feasibility study. IEEE Trans Plasma Sci 2004;32:1540-3.
Nicholson M, Dwight R. Introduction to Plasma Theory. Cambridge, UK: Cambridge University Press; 1983. p. 1-5.
Stoffels E, Kieft IE, Sladek RE, van den Bedem LJ, van der Laan EP, Steinbuch M. Plasma needle for in vivo
medical treatment: Recent developments and perspectives. Plasma Sources Sci Technol 2006;15:S169-80.
Laroussi M, Lu X. Room-temperature atmospheric pressure plasma plume for biomedical applications. Appl Phys Lett 2005;87:113902-3.
Lee HW, Kim GJ, Kim JM, Park JK, Lee JK, Kim GC. Tooth bleaching with nonthermal atmospheric pressure plasma. J Endod 2009;35:587-91.
Yavirach P, Chaijareenont P, Boonyawan D, Pattamapun K, Tunma S, Takahashi H, et al
. Effects of plasma treatment on the shear bond strength between fiber-reinforced composite posts and resin composite for core build-up. Dent Mater J 2009;28:686-92.
Fricke K, Koban I, Tresp H, Jablonowski L, Schröder K, Kramer A, et al
. Atmospheric pressure plasma: A high-performance tool for the efficient removal of biofilms. PLoS One 2012;7:e42539.
Fouquet T, Petersen J, Ziarelli F, et al
. Plasma Process. Polym 2013;3:193.
Morent R, De Geyter N. Inactivation of Bacteria by Non-Thermal Plasmas, Biomedical Engineering - Frontiers and Challenges, Prof. Reza Fazel (Ed.), 2011. ISBN: 978-953-307-309-5.