Cross-Sectional Study on Self-Perception of Dento-Facial Asymmetry

Background and Objectives: Facial symmetry is a key component of facial beauty and attractiveness. However, perfect symmetry is rare, and slight asymmetries, also known as natural asymmetries, are common and contribute to the uniqueness of each face. The perception of facial asymmetry varies among individuals and can be influenced by several factors. This study aimed to investigate the self-perception of dento-facial asymmetry among a sample of Romanian individuals, focusing on their awareness, the extent to which it bothers them, and their desire for correction. Materials and Methods: A cross-sectional analytical study was conducted with 283 participants from Romania between January and February 2024. Participants completed a questionnaire designed to assess their self-perception of facial asymmetry and socio-demographic characteristics. The questionnaire included 10 questions on self-perception of facial asymmetry and 8 questions on socio-demographic data. Statistical analysis was performed using SPSS 26.0, and the Pearson Chi-square test was used for comparative analysis. Results: The sample was predominantly female (75.3%) with an average age of 32.24 years. Most participants were from urban areas (80.6%) and had university degrees (58.7%). About 28.7% of participants observed facial asymmetry, with dental asymmetry being the most frequently reported, followed by asymmetries in the eyebrows and eyelids. The right side of the face was more commonly perceived as asymmetric. Although 24.4% of participants were bothered by their asymmetry, 39.2% expressed a desire to correct it. Conclusions: One-third of participants identified dento-facial asymmetry, with the dental level being the most reported. A significant portion of participants expressed a desire to correct their asymmetries, highlighting the importance of understanding self-perception in the context of facial aesthetics. This study underscores the subjective nature of facial asymmetry perception and the varying thresholds for what is considered bothersome or in need of correction.


Introduction
Facial symmetry represents a state of balance, a correspondence of facial features in terms of size, shape, and position relative to the mid-sagittal plane, being a key component of facial beauty and attractiveness [1].Perfect symmetry, whether of the face or body, is extremely rare [2].According to Srivastava et al. [3], there is no perfect bilateral symmetry of a living body.Bishara et al. [4] consider perfect body symmetry a theoretical concept.The human face is no exception, and bilateral structures exhibit a small, often imperceptible, degree of asymmetry [5].This type of asymmetry is referred to as relative symmetry, subclinical asymmetry, slight asymmetry, or natural asymmetry [2,6].According to Ferrario et al. [6], facial asymmetry appears to be an intrinsic feature of the human face.Thus, facial asymmetry can also be found in faces perceived as beautiful [1,7,8].According to Bishara et al. (1994) [4], Sandor et al. (2007) [9], and Andrade et al. (2021) [10], this small and variable degree of asymmetry confers uniqueness and individuality to each human face.
In the literature, various criteria for classifying facial asymmetry can be found.These include the etiological classification of asymmetry presented by Cheong and Lo (2011) [11], the structural classification described by Bishara et al. (1994) [4], and the architectural classification of asymmetry described by Pirttiniemi (1999) [12].
Within dento-facial asymmetries, those present in the lower third of the face account for 74%, followed by asymmetries in the middle third at 36%, and those in the upper third of the face represent only 5% of the total dento-facial asymmetries [14].Chin deviation appears to be the most common manifestation of dento-facial asymmetry [19,20].This distribution of asymmetry within the facial thirds could be due to the maxilla's rigid interconnection with adjacent cranial structures considered stable, while the mandible is practically a mobile system with a longer growth period [2,21].The appearance of asymmetry at the mandibular level may be due to the adaptation of the anatomical structure to deviations that occur during functional activities, causing modifications and remodeling of the condyle, glenoid fossa, and mandibular body [22].
Since the degree of asymmetry of a face can range from very small, almost imperceptible, to very large, attempts have been made to find or define a threshold or a limit between normal and abnormal [4].Specialists and patients may have different views on this limit, often being subjective.A trained eye of a specialist can detect a small difference between the two hemifaces, while the patient either does not detect the asymmetry, detects it but does not consider it bothersome, considers a very small degree of asymmetry unacceptable, or is guided by how others perceive them [23].
The objective of our research was to study the perception of the participants on their own face and to determine if they consider themselves to have a dento-facial asymmetry.Also, we wanted to see if the asymmetry was considered to be unacceptable by the participants and if the participants wanted to seek treatment for it.

Study Design
A cross-sectional analytical study was conducted on a sample of 283 participants from Romania.The study was carried out from January to February 2024.

Study Phases
This study focused on the following phases: (1) description of the study sample characteristics and evaluation of self-perception of dento-facial asymmetry, and (2) comparative study of self-perception of dento-facial asymmetry based on the socio-demographic characteristics of the respondents.

Study Instrument
To achieve this study objectives, we used a questionnaire consisting of two sections.The questionnaire was designed before the actual study began due to the absence of an adequate questionnaire in the specialized literature for our research purpose.
The first section included 10 questions about self-perception of facial asymmetry and the anatomical level at which it can be found.Additionally, study participants were asked if they were bothered by facial asymmetry and if they wished to correct it.Participants were asked to look in the mirror and self-identify, through visual evaluation, the dento-facial asymmetries they believed they had.To evaluate the attitudes or perceptions of study participants to the questionnaire questions, a 5-point Likert scale was used, with responses ranging from strong agreement to strong disagreement, with intermediate positions being agreement, neutral, and disagreement.
The second section included 8 questions about general socio-demographic data.The questionnaire was created using the Google Forms web application and was disseminated online via email and messaging applications such as WhatsApp and Messenger by sending a link that the participants accessed.

Statistical Analysis
Participants' responses were stored in a database using Microsoft Excel.Statistical analysis was performed using SPSS 26.0 (IBM, Armonk, NY, USA) for Windows.The following statistical parameters were calculated: arithmetic mean, standard deviation, standard error of the mean, and median.The Pearson Chi-square test was used for comparative analysis of results based on demographic variables.A p-value below 0.05 was considered statistically significant.For the study of correlations between physical activity level, incorrect posture, presence of dento-facial asymmetry, and existence of body asymmetry, Spearman's rho correlation coefficients were calculated, considering the qualitative-ordinal nature of the analyzed variables.

Ethical Considerations
Prior to the study, ethical approval was obtained from the Research Ethics Committee of "Grigore T. Popa" University of Medicine and Pharmacy in Iasi, nr.149/3.02.2022.All study participants signed an informed consent form approved by the Research Ethics Committee of "Grigore T. Popa" University of Medicine and Pharmacy in Iasi.

Characteristics of the Sample
The characteristics of the sample are presented in Table 1.The respondents to the questionnaire were predominantly female (75.3%) and relatively young; thus, the average age of the patients in the sample was 32.24 ± 10.192 years.Women were slightly older than men, with an average age of 33.26 ± 10.468 years compared to 29.16 ± 8.662 years.Most patients came from urban areas (80.6%); additionally, more than half of them (58.7%) had university degrees, half were single (51.2%), and almost half were married (43.1%).Furthermore, 63.9% of patients reported having average or above-average income.Regarding professions, most patients were employed, with 18.7% working in the medical field; also, a significant proportion of patients were students, accounting for 29.0%, with nearly half of them being general medicine students (13.8%).Just over 60% of patients (61.1%) lived on the 1st-2nd or 3rd-4th floors.

Evaluation of Self-Perception of Dento-Facial Asymmetry
First, patients were asked if they generally observed any dento-facial asymmetry in their face.Only a quarter of them agreed with this phenomenon (28.7%), with 17.3% localizing the asymmetry on the right side and 14.8% on the left side (Table 2).Self-perceived asymmetries are presented in the order of frequency reported by patients: dental asymmetry, eyebrow asymmetry, eyelid asymmetry, nasal asymmetry, mouth asymmetry, cheek asymmetry, and chin asymmetry, with chin asymmetry being perceived by the fewest patients (Table 3).
Only 24.4% of them considered that these asymmetries bother them, with the majority being neutral (41.0%) or disagreeing with this statement (34.7%).However, a higher percentage of patients, almost double, declared that they would like to correct their observed dento-facial asymmetry (39.2%); a third were neutral (34.3%) and just over a quarter partially or totally disagreed (26.5%) (Table 4).Significant statistical differences were also observed between genders regarding the presence of observed dento-facial asymmetries; thus, a higher proportion of women noticed such asymmetries (32.9%) compared to only 15.8% of men.Similarly, nearly double the proportion of women than men (47.4% vs. 25.8%) reported such asymmetries in their eyebrows.Other significant statistical differences were observed in dental asymmetries-although relatively similar percentages of women and men expressed full or partial agreement about the presence of these asymmetries (46.9% vs. 48.6%), the proportion of women who strongly agreed was almost four times higher than the similar proportion of men (16.9% vs.only 4.3%).No other significant statistical differences were observed between genders, although it is worth noting that 32.9% of women considered their eyelids to be asymmetric compared to only 25.7% of men, and 24.4% of women considered their mouth corners to be asymmetric compared to only 20.0% of men.In total, 27.7% of women were bothered by the dento-facial asymmetries they had observed, compared to only 14.3% of men, but this time the difference between the genders was not statistically significant, and the percentages of patients who wanted to correct these asymmetries were similar for both women and men, around 40% (Table 5).Overall, no significant statistical differences were observed between the two age groups regarding the percentages of patients who observed dento-facial asymmetries.Thus, 28.4% of patients under 30 noticed such asymmetries, similar to 28.9% of those over 30.However, a significantly higher percentage of younger patients observed eyebrow asymmetries compared to patients over 30 (48.0% vs. 35.6%).No other significant statistical differences were observed, although it is worth noting that younger patients reported slightly higher percentages of asymmetries in the eyelids (33.1%), cheeks (23.0%), and chin (12.9%), while patients over 30 reported higher percentages of dental asymmetry (50.3%) compared to younger patients (44.6%).Regardless of age group, about a quarter of patients were bothered by the dento-facial asymmetries they observed, and the percentage of those who wanted to correct these asymmetries was higher in younger patients (41.2%) compared to patients over 30 (37.0%) (Table 6).
In total, 40.0% of rural patients believed they had dento-facial asymmetries, compared to only 25.9% of urban patients, a significant and statistically important difference.Slightly higher percentages of rural patients localized these asymmetries in the eyelids (34.5%), mouth corners (30.9%), and teeth (52.8%), but these differences were not statistically significant compared to similar percentages observed in urban areas.It is also noted that the proportion of urban patients who were bothered by their dento-facial asymmetries was slightly higher than the similar proportion of rural patients (25.5% vs. 20.0%),but the percentages of patients who would like to correct these asymmetries were very close in both environments (40.0% in rural areas and 39.0% in urban areas) (Table 7).No statistically significant differences were observed among the three categories of patients identified by their education level regarding the observation of dento-facial asymmetries.However, a significant statistical difference was noted in the self-assessments related to the corners of the mouth, with this facial asymmetry being reported by 22.9% of patients with university education and 17.6% of those with postgraduate education (p = 0.044).
The same observation applied to the self-perception of dento-facial asymmetry based on the marital status of the respondents, with discrepancies between the four categories of respondents that did not reach statistical significance.
The most respondents who reported observing dento-facial asymmetries belonged to the category with average income (33.7%);this percentage was significantly higher than the similar percentages observed in the other categories of respondents: only 26.5% of those without income, 23.5% of those with minimum income, and 25.7% of those with above-average income (p = 0.002).
Another significant statistical difference in the sample related to dental asymmetry, with 45.6% of respondents without income, 44.1% of those with minimum income, and 43.2% of those with above-average income observing that they have asymmetric teeth (p = 0.028).
The only significant statistical difference in the sample at the level of dento-facial asymmetries was observed in the teeth; thus, 66.7% of self-employed or unemployed respondents considered their teeth to be asymmetric, compared to only 40.4% of employees, 42.7% of students, and 55.9% of patients with other professions (p = 0.023).
However, significant statistical differences were observed between the four categories of respondents identified by their housing type regarding the presence of dento-facial asymmetries.Thus, a third of patients living on the ground floor (33.8%) believed they have such asymmetries, compared to 24.1% of those living on the 1st-2nd floors, 30.4% of those living on the 3rd-4th floors, and 28.9% of those living on upper floors (p = 0.027).Similar percentages of patients living on intermediate floors ranged between 30 and 35%, with the recorded difference being statistically significant (p = 0.013).

Discussion
Peck et al. (1991), following a study on postero-anterior cephalograms, stated that the stability of the facial complex is higher in areas closer to the skull, presenting small degrees of asymmetry.They reported the greatest deviations at the mandibular level, moderate deviations at the zygomatic level, and minor deviations in the orbital area [24].According to Haraguchi et al. (2008), dento-facial asymmetry is equally distributed among skeletal classes I, II, and III [21].However, other studies have shown a greater association of dento-facial asymmetry with skeletal class III [22] or a lower association with skeletal class II [14].Regarding the distribution of asymmetry at the frontal level, studies support the predominant involvement of the left hemiface [2,6,21,25].This can be attributed to greater growth of the right hemiface, consistent with the larger dimensions of the skull and brain on the right side [2,6].Rohrich et al. (2016), in a study conducted on photographs, showed that the chin and nose are deviated towards the smaller hemiface [26].As for the distribution of facial asymmetry by gender, it appears to be equal between women and men according to studies conducted so far [2,5,22,27].However, these results sometimes differ, and depending on the characteristics of the studied group and the method used for evaluating facial asymmetry, there are also studies that have found higher values for asymmetries in the upper face [25] and the middle face [7,26,28].Chatrath et al. (2007), in a study conducted on a group of patients seeking rhinoplasty, found a very high percentage, 90%, of significant dento-facial asymmetries [29].MacDonald et al. (2012), in a study conducted on a group of patients seeking blepharoplasty, reported a 75% percentage of patients with asymmetry in the eyebrows and/or eyelids greater than 2 mm [30].
Identifying a perception threshold for dento-facial asymmetry is a complex process influenced by numerous factors, including the observer's level of training regarding dentofacial asymmetry, gender, the importance the observer places on dento-facial asymmetry, the part of the face where the asymmetry manifests, and the facial element affected by asymmetry [22].Naini et al. (2012), in a study conducted to determine how the severity of facial asymmetry influences a person's attractiveness, showed that for deviations of the chin less than 5 mm, facial asymmetry is negligible for patients and they do not wish to correct it.However, for deviations greater than 5 mm, patients' desire to seek surgical treatment to correct the asymmetry increases.Additionally, the same study identified the main factors influencing the desire of patients with dento-facial asymmetry to seek surgical treatment: age, gender, and ethnicity [31].Thus, as patients age, their desire for surgical treatment of dento-facial asymmetry decreases, men are less likely than women to seek surgical methods, and Caucasians are more likely to seek surgical treatment [31].
According to Wang et al. (2017), knowing the limit at which acceptable asymmetry becomes unacceptable for the patient is of utmost importance for pre-surgical evaluation, as it can improve the proposed treatment plan and, consequently, patient satisfaction by establishing realistic expectations from the treatment [23].
In the context of a stimulus that draws a person's attention to themselves (looking at their image in the mirror), that person becomes more self-aware and more attentive to the differences between their ideal self and the real self (seen in the mirror) [32].This way, the person can notice their own dento-facial asymmetry.On the other hand, Lu and Bartlett (2014) believe that a person looking at themselves in the mirror and seeing their inverted image may not be able to accurately assess their expressiveness and attractiveness, with the perception of their own facial asymmetry being affected by the inverted image [33].
Another limitation of this study is represented by the sample used, which is not representative for any population.
In the conducted study, only a quarter of the patients reported having dento-facial asymmetry; however, it is interesting to note that once they became aware of the asymmetry, patients were able to locate it correctly.Approximately half localized it on the right side and about half on the left side-the two percentages combined being almost equal to the percentage of patients who generally noticed asymmetries and practically had no doubts in specifying it correctly.These results confirm the data provided by Chatrath et al. (2007), who reported that about half of the patients seem to be aware of the presence of dento-facial asymmetry [29].On the other hand, MacDonald et al. (2012), in a study conducted on a group of patients where approximately three-quarters of them had facial asymmetries, emphasized that no patient brought up asymmetry as a reason for seeking medical attention, suggesting that they were not aware of its presence [30].
The most frequently reported asymmetry by patients is at the dental level.Thus, almost half of them believe they have asymmetric teeth, predominantly on the right side, while less than a quarter of patients locate the same asymmetry on the left side.This is interesting because, according to studies conducted so far, deviations of the maxillary midline up to 4 mm or sometimes even larger seem to go unnoticed by non-specialists [34].On the other hand, asymmetry due to different shapes of the central maxillary incisors is noticed by non-specialists even with a 0.5 mm difference between the lengths of the vestibular faces of the two central maxillary incisors, and gingival contour asymmetry at the maxillary frontal area is noticed at differences of 1.5 mm [35].These findings suggest that when patients self-evaluated dental asymmetry, they considered not only the midline deviation but also other determining factors of smile aesthetics.
Next in the order of reported asymmetries are the eyebrows, with less than half of the patients considering their eyebrows asymmetric, and less than a quarter thinking that the right eyebrow is lower.These results are consistent with those reported by Perumal (2018), who found a significant percentage of patients with eyebrow asymmetry, with most presenting a lower right eyebrow in the studied group [36].
Following in the order of frequency of asymmetries are the eyelids, with more than a quarter of patients considering them asymmetric, most believing the right eyelid is lower.This result is somewhat surprising, as the literature highlights that patients are often unaware of asymmetry in the periocular area [30,37].
A quarter of respondents consider their nose to be deviated to one side, with most reporting a deviation to the right side.This result is also interesting.In specialized studies, the nose, being centrally located on the face, is immediately noticeable, and Rohrich et al. (2017) reported a high percentage of patients who consider their nose to be deviated [26].
Less than a quarter of patients believe their mouth corners are asymmetric, with most observing the asymmetry on the right side.Yamamoto et al. (2015) also reported that lip asymmetries are less common in the population [38].
Less than a fifth of respondents believe they have a flatter cheek, with the majority indicating the right cheek.According to Zhang et al. (2023), non-specialists tend to confuse cheek asymmetry with mandibular asymmetry [39].
Patients most rarely observed asymmetries at the chin level.This aspect contradicts findings in the specialized literature.Most studies show that the highest degree of facial asymmetry is found in the lower third of the face, especially at the chin level, with this type of asymmetry being the easiest to detect by non-specialists [39].This is the hierarchy of facial regions considered asymmetric from the patients' perspective.It is also notable that in all cases, patients predominantly notice asymmetry on the right side of the face.In the specialized literature, on the contrary, left hemiface asymmetry is more common [6].Since this study is one of patient self-evaluation, it is possible that participants did not accurately evaluate their face due to the inverted mirror image.
On the other hand, patients are not very bothered by the dento-facial asymmetries they have observed.Thus, only a quarter of them believe these asymmetries bother them, with the majority of patients being neutral or disagreeing with this statement.Conversely, a higher percentage of patients, nearly double, declare that they would like to correct the observed dento-facial asymmetry; a third are neutral, and just over a quarter partially or totally disagree.

Conclusions
Based on this study, we conclude the following: One-third of the participants identified the presence of a dento-facial asymmetry; The most frequently reported dento-facial asymmetry by participants is at the dental level, followed by asymmetry in the eyebrows and eyelids; According to the observations of study participants, the right side is more affected by facial asymmetry; A small portion of study participants are bothered by the presence of dento-facial asymmetry, but twice as many patients declare a desire to correct it.

Table 1 .
Demographic characteristics of the investigated sample.

Table 2 .
Evaluation of self-perception of dento-facial asymmetry.

Table 3 .
Self-perceived asymmetries reported by patients.

Table 5 .
Comparative evaluation of dento-facial asymmetries by gender.

Table 6 .
Comparative evaluation of dento-facial asymmetries by age group.

Table 7 .
Comparative evaluation of dento-facial asymmetries by environment.