THE RELATIONSHIP BETWEEN COLOR, AESTHETIC PERCEPTION, AND THE MODIFICATION OF INCISOR INCLINATION.

Background: The smile, one of the most remarkable characteristics of the facial physiognomy, has a great influence on the social perception. The color is a basic component of the dental composition. Objective: This study evaluates the coloristic parameters and esthetic perception regarding the changes brought about by dental inclination. Material and methods: The studied sample consisted of 50 students with complete dentition and no lesions in the upper frontal group. Standardized lighting and positioning conditions were created for each subject. At skin level, the Frankfurt plane was marked. The neutral position of the patient's head was determined, chosen as the reference position (p0): the Frankfurt plane (0 degrees) and the bipupillary line parallel to the ground. To simulate orthodontic torque, the subject was asked to tilt their head posteriorly (+15 degrees) and then anteriorly (-15 degrees) relative to the reference position p0. The Frankfurt plane was adjusted to correspond to the markings for to these degrees, resulting in two new positions, p+15 and p-15. Macro intraoral photographs corresponding to the three head angles (p0, p+15, p-15) were taken using a digital camera stabilized with a tripod with a threedimensional rotating head and height adjustment. The photographs were imported into Adobe Photoshop for color analysis. Digital measurements were made in the CIELAB color space, which distinguishes color differences using three parameters (L*,a*,b*) and correlates them with the human eye's visual perception. The reference point was the middle of the vestibular face of the upper central incisor. The numerical values of color changes were compared using statistical tests in the OriginLab program. For the evaluation of aesthetic perception, an online questionnaire was conducted via Google Forms in which observers selected the most attractive photographs based on color perception. Results : The statistically significant regressions are as follows: those for the L* values in all three inclinations: anterior(-15 degrees), posterior(+15 degrees), total(-15, +15 degrees), as well as for the a* value (+15 degrees) and the b* value (-15, +15 degrees). With the head tilted anteriorly, the central incisors are retruded and appear darker and more yellowish, whereas with the head tilted posteriorly, the central incisors are protruded and appear brighter and more greenish. The values remain unchanged for the rest of the parameters. Following the questionnaire, 95% of the observers preferred the pictures in which the central incisors appeared brighter. Conclusions: Orthodontic treatments involving the application of torque forces to the upper incisor group produces changes in color perception. [ABSTRACT FROM AUTHOR]

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