Atmospheric pressure non-thermal glow discharges have shown a considerable promise for medical and dental applications. These kinds of plasmas are capable of producing short-lived chemical active species, which are propelled toward a surface to be treated. A plasma needle as a source of non-thermal glow discharge, which works under atmospheric pressure, was designed and operated at 20 kHz. The preliminary studies revealed that the device can operate with various flow of different gases such as He and Ar. According to the optical measurements, the reactive species such as O, H, N, and N2 were detected experimentally via emission spectrometer. The plasma temperature was recorded at T = 28˚C. The thermal and structural effects of plasma needle on a tooth in ex-vivo conditions were investigated and a safe distance for the plasma-tooth interaction was determined.