Abstract
BackgroundTo test the hypothesis that in profile smiling view, for ideal aesthetics, a tangent to the labial face of the maxillary central incisor crowns should be approximately parallel to the true vertical line and thereby perpendicular to the true horizontal line.MethodsAn idealized female image was created with computer software and manipulated using the same software to construct an “ideal” female profile image with proportions, and linear and angular soft tissue measurements, based on currently accepted criteria for idealized Caucasian profiles. The maxillary incisor labial face tangent was altered in 5° increments from 70 to 120°, creating a range of images, shown in random order to 70 observers (56 lay people and 14 clinicians), who ranked the images from the most to the least attractive. The main outcome was the preference ranks of image attractiveness given by the observers.ResultsThe most attractive inclination of a tangent to the labial face of the maxillary incisor crowns in profile view in relation to the true horizontal line was 85°, i.e. 5° retroclined from a perpendicular 90° inclination. The most attractive range appears to be between 80 and 90°. Excessive proclination appeared to be less desirable than retroclination. Beyond 105° most observers recommend treatment.ConclusionIn natural head position, the ideal inclination of the maxillary incisor crown labial face tangent in profile view will be approximately parallel to the true vertical line and thereby approximately perpendicular to the true horizontal line.
Highlights
To test the hypothesis that in profile smiling view, for ideal aesthetics, a tangent to the labial face of the maxillary central incisor crowns should be approximately parallel to the true vertical line and thereby perpendicular to the true horizontal line
Traditional measurement of maxillary incisor inclination relies on cephalometric techniques, essentially involving drawing the long axis of the maxillary central incisor from tip to apex and extending the line to meet any of a number of anatomical reference planes, such as the maxillary plane, Frankfort plane or sella-nasion plane, from which incisor inclination is measured
The results of this investigation appear to indicate that with a patient in natural head position, the ideal inclination of a tangent to the labial face of the maxillary incisor crowns in profile view will be approximately parallel to the true vertical line and thereby approximately perpendicular to the true horizontal line
Summary
To test the hypothesis that in profile smiling view, for ideal aesthetics, a tangent to the labial face of the maxillary central incisor crowns should be approximately parallel to the true vertical line and thereby perpendicular to the true horizontal line. The cornerstone of treatment planning in orthodontics and orthognathic surgery is the relationship between the maxillary incisors and the upper lip, the so-called lipincisor relationship, and the relationship of this complex to the rest of the face. This relationship depends on the three-dimensional position of the maxillary incisors, i.e. vertically in relation to the degree of incisor exposure, sagittally in terms of incisor protrusion or retrusion, and transversely in terms of the dental midline in relation to Kingston and St George’s Hospitals and St George’s Medical School, Blackshaw Road, London SW17 0QT, UK. The inclination of anatomical reference planes is subject to considerable individual variability [1], and these would affect the measured incisor
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