The basic color of a natural tooth can be affected by different discoloration that form the basis for the bleaching process. The therapeutic procedure which is used also depends on the causes that led to discoloration. The causes are different in the manner, place and intensity of occurrence and are dependent on the reaction of the dental tissues. Discoloration can be divided into internal and external or both forms can be present. Hydrogen peroxide or one of its variants most often appears as an active base compound in bleaching agents. As teeth whitening is nowadays becoming more common, the negative effects of hydrogen peroxide should be taken into account. Due to various whitening techniques and the development of a large number of commercially available products, the occurrence of whitening mistakes has increased. The most common clinical signs of these mistakes are hypersensitivity of the teeth to external stimuli and irritation of the surrounding soft tissue, where these changes are moderate and can go away on their own after a certain time. When whitening avital teeth, the occurrence of root resorption is one of the possible side effects. Upon application of cold atmospheric plasma, using the dielectric barrier discharge technique, it is not necessary to apply an additional bleaching agent because the created plasma field leads to the decomposition of oxygen molecules, which are located inside the dentinal tubules and the cavity itself, to active oxygen atoms. The active oxygen atoms are attached onto the pigments, leading to their decomposition and color change. In this way, the whitening effect is achieved within the dentinal tubules and the surrounding dentin without the risk of the agent penetrating the surrounding periodontal tissue and leading to root resorption.