Normality mediates the effect of symmetry on facial attractiveness

Assessment of the golden proportion in natural facial esthetics: A systematic review

STATEMENT OF PROBLEM

Faces considered attractive tend to possess a general harmony; however, scientific studies on the quantitative basis of human facial attractiveness are still sparse. The golden proportion has been the most documented ratio, but the actual existence of codified facial ratios in facially attractive individuals remains unclear.

PURPOSE

The purpose of this systematic review was to evaluate the deviation from the golden proportion in the measurements of different natural vertical facial ratios.

MATERIAL AND METHODS

A comprehensive search of the electronic databases that included PubMed/MEDLINE, Web of Science, Embase, Scopus, Scopus Secondary documents, and the Cochrane Database of Systematic Reviews was conducted using the terms "golden proportion", "golden proportions", "golden ratio", "golden ratios", "golden number", "golden section", "divine proportion", "divine proportions", "divine ratio", "divine ratios", and "Fibonacci" in combination with 1 or more of the ensuing terms: "facial proportion", "facial proportions", "facial measurement", and "facial measurements". Deviation of the facial proportions from the golden proportions was further analyzed by using a 1-sample t test (α=.05).

RESULTS

The 1-sample test showed no significant difference among the means of each variable (P>.05), suggesting that the golden proportion is found in natural facial esthetics.

CONCLUSIONS

No significant association was found between the golden ratio and facial evaluation scores among all ethnicities. The measurements and proportions for facial balance in the study population showed that the participant's facial height proportions did not follow the golden proportion.

Revealing the representative facial traits of different sagittal skeletal types: decipher what artificial intelligence can see by Grad-CAM

OBJECTIVES

Aesthetic improvement is a significant concern in dental therapy. While orthodontic treatment primarily targets hard tissue, the impact on soft tissue and the extent of these changes remains empirical. This study aims to unveil the intricate relationship between facial soft tissue and skeletal types using artificial intelligence (AI) analysis.

METHODS

First, we collected a dataset of 1044 3-side-photographs and categorized them based on cephalometric measurements. After pre-processing and data augmentation, samples were fed to two independent models (Sfa, Res model) for training and testing. After validating that the Sfa model could accurately recognize the skeletal types based merely on photographs, Grad-CAM algorithm was utilized for model decipherment. Verification of the vital traits were carried out by facial adjustment simulation.

RESULTS

The Sfa model demonstrated superior accuracy (0.9293) in identifying skeletal types based solely on soft tissue, compared to the Res model (0.8395) and even trained orthodontists (0.764), testifying our hypothesis that AI could be more capable of processing imperceptible cues compared to mankind. Intriguingly, Grad-CAM revealed that cheek volume, forehead, chin and nasolabial traits could be representative features of each type, exceeding the traditional knowledge which merely concerns mandible and chin.

CONCLUSION

By constructing a deep learning model as a classifier and then decipher it with Grad-CAM, we revealed the subtle and unnoticed cues associating skeletal and soft tissue, as well as provided a novel approach that could aid practitioners in devising tailored treatment plans for enhanced esthetic outcomes.

CLINICAL SIGNIFICANCE

The proposed AI methods offer valuable assistance to practitioners in identifying uncoordinated facial traits that may detract from a patient's attractiveness. By incorporating these insights into customized treatment plans, dental therapy can maximize esthetic benefits for individual patient.

Association between Facial Metrics and Mate Rejection for Long-Term Relationship by Heterosexual Men

Investigations on mate choice in humans frequently report preferences, but there is little knowledge about what is important for rejection by a potential mate. The present study aims to verify if facial asymmetry and facial disharmony have an influence on mate rejection by men. We hypothesized that more asymmetric and disharmonious faces would be more rejected. For this purpose, photographs of women’s faces were presented in pairs by self-declared heterosexual men. It was requested they reject one of the faces as a potential mate for a long-term relationship. Women’s faces were also analyzed to measure facial asymmetry and facial disharmony. We used a linear mixed model to evaluate the effect of the cited metrics on each face’s number of rejections. We found that the female metrics influenced mate rejection only if associated with male age and income. The older participants rejected female partners with asymmetric faces. We suggest that aging makes men more demanding in mate choices, at least considering facial asymmetry. We concluded that rejection could be a key variable in mate choice studies, but further research is needed to clarify its effects.

Quantitative analysis of soft tissue sagging after lateral midface fractures: A 10-year retrospective study

BACKGROUND

Lateral midface fractures occasionally require open reduction and internal fixation to restore function and facial symmetry. However, some patients retain facial asymmetry despite undergoing surgery due to hard tissue displacement or soft tissue sagging. This study aimed to determine the influence of soft tissue sagging on the postoperative facial symmetry.

METHODS

We examined the medical records of 590 patients who underwent planned plate removal after lateral midface or zygomatic bone fractures. After applying the inclusion and exclusion criteria, we analyzed 106 cases of lateral midface fractures for hard tissue displacement and soft tissue sagging using pre- and postoperative radiological imaging and postoperative face scanning.

RESULTS

We observed significantly larger soft tissue sagging (p < 0.001) and hard tissue displacement (p = 0.006) on the fractured side than on the non-fractured side. There was no correlation between differences in the soft tissue sagging and those in the hard tissue displacement (|rho|=0). Linear regression analysis showed no statistical influence of sex or age group on the soft tissue sagging and hard tissue displacement.

CONCLUSION

Therefore, we recommend treating soft tissue sagging as a discrete aspect of midfacial fracture treatment to achieve optimal postoperative facial symmetry. From a clinical perspective, we recommend better soft tissue management during open fracture treatment than focusing mainly on the reduction of bony hard tissues.

Formal models for the study of the relationship between fluctuating asymmetry and fitness in humans

OBJECTIVES

To evaluate three of the main verbal models that have been proposed to explain the relationship between fluctuating asymmetry and fitness in humans: the "good genes," the "good development," and the "growth" hypotheses.

MATERIALS AND METHODS

A formal model was generated for each verbal model following three steps. First, based on the literature, a theoretical causal model and the theoretical object of inquiry were outlined. Second, an empirical causal model and the targets of inference were defined using observational data of facial asymmetries and life-history traits related to fitness. Third, generalized linear models and causal inference were used as the estimation strategy.

RESULTS

The results suggest that the theoretical and empirical assumptions of the "good genes" hypothesis should be reformulated. The results were compatible with most of the empirical assumptions of "the good development" hypothesis but suggest that further discussion of its theoretical assumptions is needed. The results were less informative about the "growth" hypothesis, both theoretically and empirically. There was a positive association between facial fluctuating asymmetry and the number of offspring that was not compatible with any of the empirical causal models evaluated.

CONCLUSIONS

Although the three hypotheses focus on different aspects of the link between asymmetry and fitness, their overlap opens the possibility of a unified theory on the subject. The results of this study make explicit which assumptions need to be updated and discussed, facilitating the advancement of this area of research. Overall, this study elucidates the potential benefit of using formal models for theory revision and development.

The Effects of Pitch Manipulation on Male Ratings of Female Speakers and Their Voices

Vocal and facial cues typically co-occur in natural settings, and multisensory processing of voice and face relies on their synchronous presentation. Psychological research has examined various facial and vocal cues to attractiveness as well as to judgements of sexual dimorphism, health, and age. However, few studies have investigated the interaction of vocal and facial cues in attractiveness judgments under naturalistic conditions using dynamic, ecologically valid stimuli. Here, we used short videos or audio tracks of females speaking full sentences and used a manipulation of voice pitch to investigate cross-modal interactions of voice pitch on facial attractiveness and related ratings. Male participants had to rate attractiveness, femininity, age, and health of synchronized audio-video recordings or voices only, with either original or modified voice pitch. We expected audio stimuli with increased voice pitch to be rated as more attractive, more feminine, healthier, and younger. If auditory judgements cross-modally influence judgements of facial attributes, we additionally expected the voice pitch manipulation to affect ratings of audiovisual stimulus material. We tested 106 male participants in a within-subject design in two sessions. Analyses revealed that voice recordings with increased voice pitch were perceived to be more feminine and younger, but not more attractive or healthier. When coupled with video recordings, increased pitch lowered perceived age of faces, but did not significantly influence perceived attractiveness, femininity, or health. Our results suggest that our manipulation of voice pitch has a measurable impact on judgements of femininity and age, but does not measurably influence vocal and facial attractiveness in naturalistic conditions.

Subjective and Objective Evaluation of the Symmetry of Maxillary Incisors among Residents of Southwest Poland

Dental aesthetics is an essential factor affecting people’s psychosocial wellbeing. One of the most critical components of an aesthetic smile is symmetry within the dentition. Dentists and orthodontists, unlike laypersons, are critical in assessing dental aesthetics. This study aimed to evaluate the accuracy of patients’ assessment of the symmetry of their maxillary incisors and some factors that influence it. The study was conducted on 83 participants aged from 11 to 39 years. First, the participants filled out a questionnaire to obtain patients’ opinions of the symmetry of their upper incisors. This stage was followed by an intraoral examination, during which we used a digital caliper to measure the width of four maxillary incisors. The data were entered into STATISTICA v. 13.3. The following conclusions were drawn from the study. First, the respondents were generally able to determine the asymmetry of the incisors. Second, among the maxillary incisors, the participants defined the symmetry of maxillary central incisors more accurately than the maxillary lateral incisors. The cut-off value for incisor asymmetry noticeable to a layperson is 0.2 mm for maxillary medial incisors and 0.55 for maxillary lateral incisors. Third, we found no dependence of the accuracy of the assessment of incisor asymmetry on the age of the subjects; however, in our study group, the age range (spread) was not significant, so further studies are recommended. Finally, results concerning the relationship with gender showed that males assess the level of symmetry of their maxillary incisors more accurately than females.

Assessment of the Orbital and Auricular Asymmetry in Italian and Sudanese Children: A Three-Dimensional Study

The evaluation of the symmetry of orbital and ear soft tissues is important for aesthetic and reconstructive surgery. However, little information is available for these facial regions, especially in children. We analyzed the orbital and auricular symmetry in 418 Italian and 206 Sudanese subadult males divided into three age groups (8–11, 12–15, and 16–19 years old). Orbital and auricular height and width were measured for calculating fluctuating and directional asymmetry indices. Differences in asymmetry indices according to ethnicity and age group were assessed through the two-way ANOVA test (p < 0.01), while differences in the prevalence of right or left asymmetry according to ethnicity were assessed through the chi-square test. On average, directional asymmetry indices ranged from −2.1% to 1.1%, while fluctuating asymmetry indices ranged between 2.9% and 5.4%, corresponding to a small effect size and to 1.06–2.34 mm actual dimensions. Sudanese subjects showed a greater asymmetry for all the indices except for the fluctuating asymmetry of orbital height (p < 0.01). The directional asymmetry of auricular width increased with age. A prevalent right-side asymmetry was found for all the orbital indices (p < 0.001) in both populations, although significantly more prevalent in Sudanese individuals (over 83% for both measures), while auricular measures showed a prevalent left asymmetry exclusively in the Sudanese but with lower percentages. Aside from the limited effect size, the results proved the ethnic variability of asymmetry of orbital and auricle regions in children and suggest the need to collect more population data.