Different cultures have varying concepts of beauty, with different things considered beautiful. However, what is common to all is the pursuit of beauty, and physical attractiveness plays a significant role in everyday life, with dental appearance being an integral part of it. The face is the only part of the human body that is rarely covered, making it constantly available for aesthetic evaluation by others, and its primary role is in facilitating communication and interaction with the environment. Developmental and acquired irregularities and discoloration of even a single tooth can disrupt the harmonious appearance, which becomes immediately noticeable. The primary factors determining the appearance of teeth include shape and position, color, tooth arrangement, and quality of restorations. Tooth color is one of the most important factors contributing to self-confidence. White teeth are positively associated with social competence, intellectual abilities, and psychological adjustments. Color is a visually perceptual property resulting from the spectrum of light (distribution of light energy relative to wavelength) and is realized in the interaction of the eye with the spectral sensitivity of light receptors. The spectrum produces seven colors of light of various wavelengths that reflect tangible living matter and inanimate objects. Albert Munsell was the first to explain the human visual system in detail. His empirical analysis of color organization is the basis of all modern color coordination systems today, dividing the three-dimensional space into three dimensions: hue, lightness, and chroma. In 1976, the CIE recommended the use of color space and the corresponding mathematical expression for determining color differences. CIE 1976 (Lab*), or abbreviated CIELAB, is applied in industries using dyes. One of the key advantages of the CIELAB color space is that it attempts to place human color perception within a mathematically defined framework. This means that distances between points in this space better correlate with perceptual color differences experienced by people. In other words, the difference between two points in the CIELAB color space is more related to how people perceive color differences than is the case in other spaces. The total color difference or colorimetric difference (ΔE*) represents the difference between two colors in the CIE system. It is defined as the Euclidean distance between the coordinates for two color positions, reference, and sample. The latest revised formula for color difference is CIEDE2000, which, in addition to lightness, saturation, and hue, includes differences between saturation and hue, improving color display in the blue part of the spectrum, as well as increasing the value of a*, which affects the improvement of gray colors. Therapeutic options for changing tooth color depend on the cause of discoloration and include: in-office bleaching, at-home bleaching trays, micro and macro abrasion, composite bonding, veneers, and crowns. Of all these bleaching procedures, at-home bleaching is the least invasive because it does not involve the use of any mechanical drills that irreversibly damage or remove hard tooth structure. The procedure involves applying bleaching material to the tooth surface for a specified period. The active ingredients of most bleaching agents are compounds with a peroxide group (-O-O-), called peroxides. The most commonly used bleaching peroxide is highly reactive hydrogen peroxide (HP). In addition to HP, carbamide peroxide (CP), sodium perborate, and their combinations are also used. HP, along with oxygen-free radicals produced by its breakdown, can diffuse through hard dental tissues (organic enamel and dentin matrix) and react with chromogenic molecules. Free radicals cleave conjugated double bonds, changing the absorption energy of chromogenic molecules, which decompose into smaller ones and emit radiation of lower wavelengths in the invisible part of the spectrum. Dental hypersensitivity most often occurs in the early stages of the bleaching process and is usually temporary. Patients complain of spontaneous, intense, penetrating, or sudden pain, which can affect all teeth, several teeth, or only one tooth. Sensitivity associated with tooth bleaching is associated with the appearance of microscopic enamel defects and subsurface pores with the possibility of penetration of the bleaching agent to the pulp. Patient satisfaction is a key indicator of the quality of dental procedures, often used as a measure of success. Research has shown that whiter teeth are associated with positive personality assessments, including social competence, attractiveness, intellectual abilities, and satisfaction in relationships. Purpose: The null hypothesis of the research was that there would be no difference in tooth color after different whitening procedures and that these procedures would not cause tooth sensitivity or change the level of patient satisfaction with tooth color. The primary goal of the study was to compare the differences in tooth color using different whitening techniques over a 6-month period. Secondary objectives included assessing tooth sensitivity and the degree of patient satisfaction with the results. Participants and procedures: The study involved 60 participants who, during the initial examination, signed an informed consent form to participate in the research conducted at the Private Dental Practice Floss&Gloss in Sarajevo, approved by the Ethics Committee of the School of Dental Medicine, University of Zagreb. The participants included individuals of both genders, males and females, aged between 22 and 43, with an average age of 33.1 years of age. In the first group of 20 participants (three males and seventeen females), the Boost – 40% HP preparation was applied for in-office intensive whitening (Opalescence Boost: PF 40, Ultradent, USA). In-office whitening was conducted through three applications of 20 minutes each, in a single visit. For the second group of 20 participants (nine males and eleven females), the PF 16% CP preparation was used for athome whitening (Ultradent, South Jordan UT, USA), with tray application every day for 14 days, for four hours per day. For the third group of 20 participants (seven males and thirteen females), the PF 10% CP preparation was used for at-home whitening (Ultradent, South Jordan UT, USA), with tray application every night for 14 days, for eight hours per day. After the initial examination, using a dental probe and mirror, initial therapy was performed, i.e., nonsurgical therapy for the removal of hard and soft deposits from the teeth, supragingival plaque, and calculus removal. Following this procedure, alginate impressions were taken from the patients, and based on the impression of the probe tip, a cast was made using a spectrophotometer. The cast of the probe tip was colored and used as a template for marking the measurement tray (jig). This formed a template for positioning, i.e., ensuring the positioning of the spectrophotometer tip in the same position for each color measurement. The middle third of the vestibular surface of the maxillary six anterior teeth was marked with this tip. The tray covered the gingiva, and circular openings at the position of the spectrophotometer tip provided free space for the spectrophotometer tip. The color of the upper six anterior teeth in their middle third was spectrophotometrically measured for each participant. Color measurements were taken on four occasions: before whitening (t0), after professional teeth cleaning, then after completion of the whitening procedure (t1), and three (t2) and six months (t3) after whitening. CIE Lab and LCh values were recorded, and color changes in both color spaces (ΔEab; ΔE00) were calculated. All participants reported tooth sensitivity after the whitening procedure and six months later and assessed their satisfaction with the achieved color, color stability, duration of effect, and comfort of the procedure. The collected data were statistically analyzed using the SPSS 19.0 statistical program (SPSS, Chicago, IL, USA). Results: The results showed that there was a change in tooth color after the whitening procedure, and it was significantly higher immediately after whitening and six months later when using 10% carbamide peroxide compared to the other two whitening techniques (ΔEab=4,8; 4,9; p<0,05). The degree of tooth sensitivity after completing the whitening procedure and six months later was significantly higher in the group of participants who underwent in-office intensive whitening using 40% hydrogen peroxide compared to the other two tested techniques (p<0,05). The degree of patient satisfaction with the achieved color and its stability was significantly higher in participants whose teeth were whitened with 10% carbamide peroxide compared to other whitening techniques (p<0,05). Conclusions: The results indicated that the use of 10% CP in the at-home tray whitening technique leads to a significantly greater change in color compared to other tested techniques. Furthermore, the application of 40% HP in the intensive whitening technique causes significantly higher tooth sensitivity compared to other techniques. However, the use of 10% CP for at-home whitening results in significantly higher patient satisfaction with the achieved color and stability compared to other techniques. Ultimately, the tray-whitening technique with 10% CP results in the greatest color change, the lowest tooth sensitivity, and the highest patient satisfaction. Considering the limitations of this study, it can be concluded that the use of the tray-whitening technique with 10% CP leads to the greatest color change, the lowest degree of tooth sensitivity, and the highest level of patient satisfaction, making it a recommended safe technique for whitening natural teeth.