This study is to verify effects of tooth whitening by a directcurrent cold atmospheric nitrogen plasma as a light source for tooth whitening. Cold plasma was examined in 35% HP, 5% HP and distilled water, respectively for 20 minutes whereas control group is conducted to examine tooth whitening effect of 35% HP without cold plasma. The result of research showed that color change CIE(L*,a*,b*) are increased as time takes longer in 5 min, 10 min, 15 min and 20 min respectively and statistically it showed significant differences (p<0.01). After 20 min, A group which experiments plasma applied with 35% HP and B group that experiments plasma applied with 5% showed high changes of colors. For the result of comparing surface roughness, significant differences was indicated statistically in each group (p

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