Bactericidal applications of Low Temperature Atmospheric Pressure Plasma in dental care

Summary form only given. The atmospheric pressure plasma (APP) has been proved with great effectiveness in killing micro-organisms, and this makes it potential use in various biological and medical applications such as sterilization of medical devices, decontamination of biomaterials, and even enhancement of wound healing. Recently, some researchers investigated APP effects in dental care, such as tooth whitening and tooth plague ablation. Bondings between dentin and cavity filling materials, or between implants and dental pulp cells, were greatly enhanced by APP surface treatments. Otherwise, plasma stripping technology, usually applied in semiconductor processing, was further improved to be utilized in tooth surface bleaching. The bleaching effects of this novel low-temperature atmospheric pressure plasma (LT-APP) on dental whitening have been proved and patented. In this study, the effects of LT-APP in micro-organisms inactivation were investigated. Two bacterial species, E. coli, the most ordinary bacterial species to be used in assessment of micro-organisms inactivation, and S. mutans, playing a major role in tooth decay, were used in this study. Some plasma parameters, including two gas species, varied plasma temperature and varied plasma treatment time were selected to study the bactericidal effects of LT-APP system. From the experimental results, it was shown that significant effects of LT-APP system in bacterial killing with increasing treatment time. However, there´s no obvious difference in bacteria killing activity of varied temperature plasma. This may suggest that heat could play limited effects in microorganisms inactivation, and the discharged free radicals (superoxide anion (O₂^-), hydroxyl radical (OH·)) and other components like UV light, emitted from the plasma glow, might play the major bactericidal effects. In summary, LTAPP system, with its advantage in low processing temperature, owned great potential medical us- in surface treatments of heat sensitive materials, like human skin tissue, and also in dental care application.