Effects of malocclusions on facial attractiveness and their correlations with the divine proportion

A deep learning framework to scale linear facial measurements to actual size using horizontal visible iris diameter: a study on an Iranian population

Digital images allow for the objective evaluation of facial appearance and abnormalities as well as treatment outcomes and stability. With the advancement of technology, manual clinical measurements can be replaced with fully automatic photographic assessments. However, obtaining millimetric measurements on photographs does not provide clinicians with their actual value due to different image magnification ratios. A deep learning tool was developed to estimate linear measurements on images with unknown magnification using the iris diameter. A framework was designed to segment the eyes' iris and calculate the horizontal visible iris diameter (HVID) in pixels. A constant value of 12.2 mm was assigned as the HVID value in all the photographs. A vertical and a horizontal distance were measured in pixels on photographs of 94 subjects and were estimated in millimeters by calculating the magnification ratio using HVID. Manual measurement of the distances was conducted on the subjects and the actual and estimated amounts were compared using Bland-Altman analysis. The obtained error was calculated as mean absolute percentage error (MAPE) of 2.9% and 4.3% in horizontal and vertical measurements. Our study shows that due to the consistent size and narrow range of HVID values, the iris diameter can be used as a reliable scale to calibrate the magnification of the images to obtain precise measurements in further research.

Do the Most Attractive Faces of Patients With Class II Division 1 Malocclusion Differ From Those With the Least Attractive Faces in Terms of Angular and Proportional Measurements Assessed on Frontal and Lateral Photographs?

Background This study investigated the facial angles and proportions affecting facial aesthetics in patients with skeletal class II division 1 malocclusion between those labeled the most attractive and least attractive in each gender. Methodology The study sample included pretreatment extraoral photographs of 60 patients (30 males and 30 females) with skeletal class II division 1 malocclusion according to the ANB angle aged between 18 and 21 years. A panel of 240 laypersons (aged 20-25 years; the average age of 22.5 ± 0.37 years; 120 males and 120 females) scored the aesthetic evaluation of photographs using the visual analog scale (VAS). Two groups were created according to the mean aesthetic scores of each photograph, namely, the most attractive group with the highest aesthetic scores, and the least attractive group with the least aesthetic scores. A total of 12 patients in each group were selected. Subsequently, their angular and proportional measurements on the frontal and lateral photographs were calculated. Independent-sample t-tests were used to determine if there were significant differences in these measurements between the two groups. Results There was no significant difference in frontal variables between the most attractive and least attractive groups in each gender. The angle NPog-FH was significantly greater in the most attractive males than in the least attractive males, while there was no significant difference between the most attractive and least attractive females regarding any of the profile variables. Conclusions The most attractive females with class II division 1 were similar to the least attractive on evaluating the frontal and profile variables. In contrast, the most attractive males with class II division 1 malocclusion had more protrusion in the chin than the least attractive male patients, with no differences in other profile and frontal variables. These findings suggest considering the chin position during the diagnosis and treatment planning of class II division 1 malocclusion patients.

What do black patients expect from orthodontic treatment? The aesthetic perception of facial profile between orthodontists and black laypersons

Objective:

To evaluate the influence of anteroposterior position of the soft tissue on facial attractiveness in black people, and compare the perception of aesthetics and satisfaction between orthodontists and black laypersons.

Methods:

The sample was composed of 69 orthodontists and 69 laypersons of black ethnicity (n=138). Facial profile photographs of two black volunteers, a man and a woman, were digitally manipulated to change the position of the lips and chin, by making gradual changes of 4mm in relation to the true vertical line, simulating advance or retrusion of the soft tissues by -2, -6, -10, +2, +6, +10mm, totalling six images per sex. The photographs were classified by the research participants using a visual analogue scale (VAS), from 0 (unpleasant) to 100 (pleasant). The results were analyzed by generalized linear model and by the Fisher’s exact test, considering the level of significance of 5%.

Results:

The orthodontists and black laypersons considered straight profiles the most pleasant. The two groups classified the male profile as being more unpleasant in comparison with the female facial profile, which was concave. When evaluating all the images together, the image most indicated as being the most pleasant, once again, was the one with the straight profile, for both sexes.

Conclusion:

The influence of orthodontists’ and laypersons’ aesthetic perception on evaluating the facial profile of blacks was similar. The straight profile was classified as the most pleasant and the concave, as the most unpleasant.

Does 3-dimensional facial attractiveness relate to golden ratio, neoclassical canons, 'ideal' ratios and 'ideal' angles?

Background

The established recommendations and guidelines regarding ideal measurements for an attractive face are mostly based on data gathered among Caucasian population. The aim of this study was to examine the relationship between perception of 3-dimensional facial attractiveness and golden ratio, neoclassical canons, ‘ideal’ ratios and ‘ideal’ angles in Hong Kong Chinese.

Methods

Thirty 3-D photographs (15 males and 15 females) were shown to 101 laypersons and 60 patients seeking orthognathic treatment. The photographs were rated based on a 100 mm visual analogue scale (VAS) from 0 (very unattractive) to 100 (very attractive).

Results

More than half of the measurements (42/77) in females and thirty-two measurements in males were found to be significantly different from the ideal target value (p < 0.05) upon the comparison of the attractive faces with golden ratio, neoclassical canons, ‘ideal’ ratios and ‘ideal’ angles. Meanwhile, correlation tests between VAS scores and the parameters detected significant results (p < 0.05) in only six ratios, eight angles, one neoclassical canon and one proportion.

Conclusions

Despite several renowned ‘ideal’ parameters of attractive faces that have been recommended in the literature, only a few of them were found to be significantly correlated with attractive faces in Hong Kong Chinese.

Divine Proportions in the Assessment of Facial Esthetics—Antiquity vs Contemporary: A Systematic Review

Objective:

The objective of this research was to systematically evaluate evidence regarding the correlation between divine proportions and facial esthetics.

Materials and Methods:

An extensive literature search was performed in multiple electronic databases such as PubMed, Medline, Embase, ScienceDirect, and ProQuest which included articles published from May 1982 to March 2021 in the English language. Furthermore, only randomized clinical trials and original research studies were included. The risk of bias in the included studies was assessed by using the Cochrane risk-of-bias tool ROBVIS (Risk-of-bias VISualization tool).

Results:

A total of 2,736 articles were retrieved and 974 duplicate records were eliminated; subsequently, articles were screened based on title and abstracts, inclusion and exclusion criteria from which a total of 14 original articles were included in the systematic review. Of the 14 included studies, 5 studies showed a low risk of bias, 6 studies showed a moderate risk of bias, and 3 showed a high risk of bias. Four studies showed a positive correlation and 10 studies showed a negative correlation between divine proportions and facial esthetics.

Conclusion:

The evidence from this study suggests that there exists a weak correlation between divine proportions and facial esthetics. Hence, divine proportions are not absolute determinants and are only partially related to facial attractiveness. Further high-quality cross-sectional studies with a strong methodology are needed to establish the correlation between divine proportions and facial esthetics and to support this evidence. Trial registration number: PROSPERO CRD42022302308

Facial esthetic outcome of functional followed by fixed orthodontic treatment of class II division 1 patients

OBJECTIVES

To assess the perceived facial changes in class II division 1, convex profile patients treated with functional followed by fixed orthodontic appliances.

SUBJECTS AND METHODS

The study sample consisted of 36 pairs of pre- and post-treatment photographs (frontal and profile, at rest) of 12 patients treated with activator, 12 with twin-block, and 12 controls with normal profiles, treated without functional appliances. All photographs were presented in pairs to 10 orthodontists, 10 patients, 10 parents, and 10 laypersons. Visual analog scale (VAS) ratings of changes in facial appearance were assessed.

RESULTS

The patient groups were similar in sex distributions, age, and treatment duration. The different rater groups showed strong to excellent agreement. There were no significant differences among treatment groups (F = 0.91; P = 0.526; Wilks lambda = 0.93), raters (F = 1.68; P = 0.054; Wilks lambda = 0.83), and when testing the combined effect of treatment and rater on the results (F = 0.72; P = 0.866; Wilks lambda = 0.85). The raters detected slightly more positive changes in the activator and twin-block groups, compared to the control group, regarding the lower face and the lips, but these findings did not reach significance. Furthermore, their magnitude hardly exceeded 1/20th of the total VAS length.

LIMITATIONS

Retrospective study design.

CONCLUSIONS

The perceived facial changes of convex profile patients treated with functional, followed by fixed orthodontic appliances, did not differ from those observed in normal profile patients, when full-face frontal and profile photos were simultaneously assessed. Consequently, professionals should be skeptical regarding the improvement of a patient's facial appearance when this treatment option is used.

The Esthetic Difference of Chinese Beauty Evaluated by Two Different Human Races Based on Three-Dimensional Average Face Analysis

Supplemental Digital Content is available in the text

Purpose:

The aim of this study was to establish a new method of facial soft tissue analysis based on 3dMDface system and to find the different esthetic preferences of Chinese beauties from the Chinese and Indian evaluators perspective.

Methods:

Three-dimensional facial images of 242 females and 168 males were evaluated and ranked by 8 Chinese and nine Indians using a 10-point visual analog scale (VAS). Total 120 subjects in 2 panels (from Chinese perspective and Indian perspective) including 30 male and 30 female faces with top 30 scores were analyzed with the “average face” method respectively. Then 17 linear measurements, 13 curve measurements and 14 ratios of 4 average faces were calculated and compared with the divine proportion.

Results:

Distinct differences were founded based on the average face analysis. Similar total facial types were preferred by both Chinese and Indian evaluators, while Indian evaluators preferred a wider male face with a protrusive lower lip. Delicate noses with lower nose ridge but protrusive lower lips in females were more acceptable by Indian evaluators. The differences of linear measurements were limited in 2.0 mm except the facial width, lower facial width, upper facial height and forehead height while curve measurements differ distinctly as the table shows. No ratios equal to the divine proportion were founded.

Conclusion:

The 3D Average face based on stereophotogrammetry is a feasible method to analyze the facial characters and discrepancy of esthetic preferences. Chinese and Indian evaluators have some certain differences when judging beauties. Attractive faces have some certain ratios but not the divine proportion.

The morphology and bridging of the sella turcica in adult orthodontic patients

Background

The purpose of this study was to determine and compare the shapes, sizes, and bridging of the sella turcica in patients with different skeletal patterns and genders.

Methods

It was a cross-sectional comparative study. The samples were divided into three groups according to the skeletal pattern viz. Class I, Class II and Class III, and each group consisted of 40 samples (20 males and 20 females). The lateral cephalograms were traced and the sella turcica was assessed for its size, shape, and bridging.

Results

The mean length, anteroposterior diameter and depth of sella turcica were 8.13 ± 2.03 mm, 9.60 ± 1.43 mm and 6.40 ± 1.21 mm respectively. The mean length of sella turcica was 7.91 ± 1.52 mm in Class I, 7.32 ± 1.62 mm in Class II and 9.16 ± .2.42 in Class III skeletal pattern; anteroposterior diameter was 9.30 ± 1.02 mm in Class I, 9.15 ± 1.28 mm in Class II and 10.35 ± 1.64 mm in Class III skeletal pattern; and the depth was 6.40 ± 0.92 mm in Class I, 6.07 ± 1.01 mm in Class II and 6.74 ± .1.54 mm in Class III skeletal pattern. There were significant differences in length and anteroposterior diameter and sella turcica between Class I, Class II and Class III skeletal patterns (p = 0.01), (p = 0.01) respectively. There was no significant difference in size of sella turcica between different genders and age groups. Sixty percent of the patients studied had normal Sella morphology. Partial Sella turcica bridging and Sella turcica bridging was seen in this study in 23.33% and 11.67% of patients respectively.

Conclusion

Sixty percent of the patients had normal sella turcica. There were significant differences in lengths and anteroposterior diameters among Class I, Class II and Class III patients. The larger size was present in skeletal Class III patients.