Plasma is the fourth state of matter. It consists of charged particles, radicals, and a strong electric field, so that it is a highly reactive material. Since a plasma jet device generates plasma in the surrounding air at low temperature, it is suitable for direct treatment of target teeth. Furthermore, the produced energetic ions, free electrons, and hydroxyl radicals (OH) from the plasma contribute significantly to tooth bleaching; thus, plasma might shorten the bleaching period because of its synergistic effects on tooth bleaching.
THE DEVICE
The nonthermal atmospheric pressure plasma jet device consists of a Teflon tube,that has an inner and an outer aluminium electrode. The outer electrode is connected to a 20 kHz voltage source with a 5 KV voltage. The inner electrode is suspended and not connected to any external power source. It consists of an aluminium cylinder perforated by capillary holes of 1 mm in diameter. Helium gas with a flow rate of 2 L/min is used as feeding gas though the Teflon tube at atmospheric pressure in air. The plasma generation occurs inside the Teflon tube near the powered outer electrode. Subsequently, the plasma is driven out by helium flow to generate a plasma jet outside the Teflon tube in atmospheric pressure air. The jet length increases with the flow rate or applied voltages, and it can reach 3 cm in air.
REF : IEJ, 44, 2011
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