Aesthetic impact of the upper component of the nasolabial angle: a quantitative

investigation

ABSTRACT

Objective: A quantitative evaluation of the influence of the upper component of the

nasolabial angle (NLA-UC) on perceived attractiveness and threshold values of desire for

rhinoplasty.

Materials and Methods: The NLA-UC angle of an idealized silhouette male Caucasian

profile image was altered incrementally between -24° to 45°. Images were rated on a Likert

scale by pre-treatment orthognathic patients (n=75), laypeople (n=75), and clinicians (n=35).

Results: The results of the present investigation demonstrate that a NLA-UC angle of

between 12° to 24° is ideal, with a range of 8° to 30° deemed acceptable. Angles above or

below this range, up to -4° and 36° are perceived as slightly unattractive, and anything

outside the range of -4° to 36° is deemed very unattractive.

In terms of threshold values of desire for surgery, for patients the threshold value of desire for

surgery was 33° and above and -8° and below, and for both clinicians and lay people the

threshold value was 36° and above and -8° and below.

Patients appear to be more critical than lay and clinician groups. This stresses the

importance of using patients as observers, as well as laypeople and

clinicians, in facial attractiveness research.

Conclusions: From the results of this study, it is recommended that in rhinoplasty planning,

the range of normal variability of the NLA-UC angle, in terms of observer acceptance, is

taken into account as well as the threshold values of the desire for surgery.

Keywords: Nasolabial angle, attractiveness perception, desire for surgery, rhinoplasty

1

1. INTRODUCTION

Each facial parameter, such as the upper component of the nasolabial angle, has an ‘average’

value or ‘norm’ for a given population, which is specific for age, gender and ethnicity. Each

of these norms also has a range of normal variability, with the existence of a facial deformity

often resulting from a significant deviation of one or more facial parameters from the

accepted norm for a population. For clinical practice, it is important to know at what point the

deviation of a facial parameter moves from the acceptable range of variability to being

perceived as a facial deformity [1].

The magnitude of the deviation, whether it is due to the underlying osseocartilaginous

framework, the overlying nasal soft tissues or a combination of the two, is an important factor

in deciding when surgery may be required. If the magnitude of the discrepancy of a facial

parameter is great (for example, excessive nasolabial angle) the treatment planning decision

may be relatively straightforward. However, a significant number of patients are regarded as

“borderline” in terms of need for surgical treatment. In such patients, the decision making

process may be transferred from subjective clinical judgement to objective, evidence-based

guidance based on data from studies investigating perceptions of facial attractiveness [1].

The nasolabial angle is a potentially important factor in the perception of facial profile

attractiveness [2]. It is formed by drawing a line tangent to the nasal columella (columella

tangent) and a line tangent to the upper lip (upper lip tangent), intersecting at subnasale. This

angle will depend on the inclination of the nasal columella and the upper lip. To better

evaluate the inclination of the nasal columella, the nasolabial angle may be separated into

upper and lower component parts using a true horizontal line through subnasale, with the

patient in natural head position [1]. This will allow the columella tangent-true horizontal

plane (upper component of the nasolabial angle) and the upper lip tangent-true horizontal

2

plane angles to be assessed separately, as they vary independently [1]. The landmarks and

planes used to describe the upper component of the nasolabial angle are shown in figure 1.

The principal aim of this investigation was to evaluate quantitatively the influence of the

upper component of the nasolabial angle on perceived attractiveness, in order to find

objective evidence to aid clinicians in planning the treatment of patients requiring alteration

of the upper component of the nasolabial region. The relationship between the degree of the

upper component of the nasolabial angle and attractiveness was recorded to ascertain the

range of normal variability, in terms of observer acceptance, and to determine the clinically

significant threshold value or cut-off point, beyond which the angle is perceived as

unattractive and surgical correction is desired. The perceptions of orthognathic patients,

clinicians and laypeople were compared for these different variables.

1.1 Null hypotheses:

There is no effect of the type or degree/severity of the deviation of the upper component of

the nasolabial angle on perceived attractiveness or desire for surgery. Likewise, there is no

difference in the perception of orthognathic patients, laypeople and clinicians.

2. MATERIALS AND METHODS

Ethical approval was sought and granted for the study by the National Research Ethics

Service; NRES (UK); REC reference: 06/Q0806/46.

2.1 Images

Two-dimensional facial profile silhouettes are used routinely to assess the perceptions of

facial profile attractiveness [3,4].

2.1.1. Image creation - A facial profile silhouette image was created with computer software

(Adobe® Photoshop® CS2 software; Adobe Systems Inc., San Jose, CA, USA). The image

was manipulated using the same software to construct an “ideal” facial profile image with

3

proportions [1] and linear and angular soft tissue measurements [1,5-10] based on currently

accepted criteria for an idealized Caucasian male profile, as previously described [4].

2.1.2. Profile image manipulation - The upper component of the nasolabial angle of the

idealized profile image (image BM: 24°) was altered in 3-degree increments from 24 to 45

degrees, and in 4-degree increments from 24 to -24 degrees, in order to represent variations in

the angle and morphology of the nasolabial region (Figure 2).

2.2 Observers, questionnaire and rating method

2.2.1. Observers – Based on the results of a pilot study and power calculation, 185 observers

took part in the study, separated into three groups (pre-treatment orthognathic patients,

laypeople and clinicians; Table 1), with the following selection criteria:

● Orthognathic patients: pretreatment (only 1 consultation appointment); primary concern

was facial appearance; no previous orthodontic or facial surgical treatment; no history of

facial trauma; no severe psychological issues, e.g., body dysmorphic disorder.

● Laypeople: no previous orthodontic or facial surgical treatment; no facial deformities; no

history of facial trauma.

● Clinicians: involved in the management of patients with facial deformities. This group

included 19 clinicians in oral and maxillofacial surgery and 16 orthodontists, with 1-16 years

of experience in the clinical management of patients requiring orthognathic surgery.

2.2.2. Questionnaire - Each observer was given a questionnaire and asked to provide the

following information: age, gender, ethnic origin (White or non-White Caucasian), how

would you rate the attractiveness of your facial appearance, and how important do you think

it is to have an attractive facial appearance. An instruction sheet accompanied the

questionnaire, asking the observers to rate each image in terms of facial attractiveness using

the following rating scale:

4

1. Extremely unattractive.

2. Very unattractive.

3. Slightly unattractive.

4. Neither attractive nor unattractive.

5. Slightly attractive.

6. Very attractive.

7. Extremely attractive.

Observers were also asked whether they would consider surgery to correct the appearance if

this was their facial appearance (yes or no).

The images were placed in random order into the software application Microsoft PowerPoint®

(Microsoft Corporation, USA). Each image was identified by a randomly assigned double

letter in the top right corner of the screen (e.g. BM, PG etc.; Figure 3). A duplicate of one of

the images was used to assess intra-examiner reliability (images DO and EN). Each observer

sat undisturbed in the same room in front of the same computer and 17-inch flat screen

monitor. The presentation and the images were created in such a way that each of the profile

silhouette images, when viewed on the monitor, had the same dimensions as a normal human

head, based on an average lower anterior facial height. This helped to reduce the potential

effect of image magnification or size reduction on the observer’s perception. Each observer

examined the images in the PowerPoint® presentation by pressing the ‘Page Down’ button

on the keyboard, in their own time.

2.2.3. Rating method - The Likert-type rating scale used is largely accepted in the psychology

literature as the most useful rating method [11]. The seven-point Likert scale described above

was used by each observer to rate each image in terms of attractiveness.

2.3 Statistical analysis

5

The observer’s ratings were recorded in a Likert scale from 1 to 7. In order to assess how

perceived attractiveness varies with the upper component of the nasolabial angle, the median

and interquartile observer ratings were calculated for each angle and for each observer group;

these descriptive statistics were calculated using software that we developed using MATLAB

(The MathWorks Inc, Natick, MA, USA). Additionally, data were modelled by curve fitting

performed using MATLAB. Similarly, the software calculated the proportions in each group

suggesting a desire for surgery. Additional paired t-tests were performed using Minitab

version 16 (Minitab Inc, State College, PA, USA) following applying the Ryan-Joiner test in

Minitab used to examine if data were consistent with a normal distribution.

3. RESULTS

The variable “self-rating of attractiveness” had very few observers in its border values (very

unattractive, seven patients; very attractive, seven laypeople) and was recoded into two

levels: attractive (n = 123) vs. unattractive (n = 62). The variable “vertical face height” was

dichotomized into two levels: normal (n = 166) vs. non-increased/decreased (n = 19). Only

11 observers responded that attractiveness was very unimportant (one patient) or unimportant

(six patients and four laypeople). As a consequence this variable was dichotomized as

important vs. not important.

All the laypeople and the clinicians had Class I jaw relationship whilst 96% of the patients

had Class II or III jaw relationships. There was no significant difference in perceptions of

attractiveness between observers with skeletal Class II and III jaw relationships (P = 0.91) but

they appeared to differ significantly from those with skeletal Class I. When skeletal Class

was fitted on the patient group alone no difference was detected between skeletal Classes II

and III (P = 0.86).

6

3.1 Reliability Analysis

Analysis of the first and third quartile rankings of the Likert score indicate that there was

generally good agreement in the three observer groups with a maximum interquartile range

for all three groups of 2. For the two identical images, the first and third quartiles were

identical except for a difference of one in the first quartile in the patient assessment.

3.2 Perceived attractiveness of images

Table 2 shows the median attractiveness rating of the observers on a Likert scale from 1 to 7

is shown, where 1 indicates “extremely unattractive” and 7 indicates “extremely attractive”.

An upper component of the nasolabial angle outside the range of 8° to 24° were associated

with a reduction in the median attractiveness scores in all three groups of observers.

Repeatability was good, as images DO and EN are identical, with all three groups having the

same median attractiveness score for these images. Figure 4 shows the clinician data in

graphical form using MATLAB with a cubic curve fitted to the data (r2=0.85) showing that

angles 8° and 24° had the highest ranking. Furthermore, when taking paired observations

there was no significant difference for the patient and clinician groups when comparing the

difference in rankings of the identical images using a paired t-test, p=0.39 and p=0.17 for the

patient and clinician groups respectively. For the lay group, there was a significant difference

(p=0.2), however, the mean difference was 0.25 and hence was small.

3.2.1 Most attractive and least attractive images

Table 3 demonstrates the data in rank order from most to least attractive, sorted on the basis

of responses from the clinician group then lay group.

3.3 Outcome: Desire for Surgery

7

Table 4 demonstrates the proportion expressed as a percentage of each observer group

suggesting that surgery is required shown in rank order. The results indicate that clinicians

were generally least likely to suggest surgery for varying degrees of upper nasolabial angle.

Images DO and EN were identical, and so repeatability of the 35 clinician’s assessment was

excellent, in both cases 20% suggesting surgery. For the 75 lay people the assessment of the

two repeated images shows clear variability (24 and 37 %), which is not seen in the group of

75 patients (37 and 33%). For many of the images there was generally good agreement

among clinicians as to whether surgery is required. There was more variability in the

assessment for the patient and lay groups as indicated by fewer very low (< 25%) and very

high percentage (> 75%) of the groups suggesting surgery. Taking 50% (i.e. majority) of

each observer group as a cut-off where the majority suggested surgery, for patients the

threshold value of desire for surgery was 33° and above and -8° and below, for lay people the

threshold value was 36° and above and -8° and below and similarly 36° and above and -8°

and below for clinicians. Additionally, using MATLAB, a quadratic equation was used to

model the percentage suggesting surgery compared with nasolabial angle. For clinicians the

fit gave an equation:

0.08 x angle2 – 2.22 x angle + 25.9, (r2=0.85), hence 50% corresponds to an angle of 8.4° or

37.9°, thus very close to that obtained from the above data.

When examining whether observers suggested surgery, the data were examined for those who

considered attractiveness to be important (>2) and those who did not; for patients 68/75, for

laypeople 71/75, and all clinicians considered attractiveness to be important. An upper

component of the nasolabial angle deviations above 33° and below -4° were again associated

with a higher proportion desiring surgery.

8

For the 7 patients and 4 laypeople who did not consider attractiveness to be important, angles

greater than -8° and less than 33° were associated with a proportions of patients suggesting

surgery of below 15%. For angles of -8° and below as well as angles greater than 33° the

proportion in this group of patients suggesting surgery was at least 43%.

4. DISCUSSION

The nasal profile is a particular source of concern for some individuals, with a considerably

increased or reduced nasolabial angle being a significant reason for patients seeking

rhinoplasty. The morphology of the nasolabial region in profile view is a potentially

important determinant of perceived attractiveness and thereby knowledge of perceptions of

attractiveness, in addition to average population values, is important for clinicians correcting

facial deformities [1].

In order to determine and validate the correct nasal proportions and morphological

relationships with which to plan clinical treatment, two sources of information are required

[12]. Firstly, population averages, which permit comparison of an individual’s nasofacial

measurements and proportions to the population norms. Ideally, such data should be age,

gender and ethnicity specific. Such data are based on anthropometric studies and long-term

cephalometric growth studies of normal individuals, where available. No longitudinal data is

available for the nasolabial angle, but there is some cross-sectional data available [10].

Secondly, the perceived attractiveness of the proportions and morphological relationships

must be confirmed by the judgement of patients and the lay public, and ideally compared to

the judgement of treating clinicians. This was the main purpose of this investigation.

The results of this investigation demonstrated that increasing the NLA-UC angle deviation in

either direction from an angle of 24 degrees (Image BM) was associated with a reduction in

the median attractiveness scores in all three groups of observers. The highest attractiveness

scores were for image BM (NLA-UC angle of 24°), closely followed by image LI (angle of

9

20°), image MK (angle of 16°) and OU (angle of 12°). An angle of 8° (image PG) and both

27° and 30° (images CM and DO respectively) was deemed essentially attractive. At 4°

(image RY) and at both 33° and 36° (images FM and GR respectively), the angle was deemed

to be neither attractive nor unattractive, i.e. essentially acceptable, even if not attractive.

However, from a NLA-UC angle of -4° and below and 36° and above, the images were

viewed as slightly unattractive by all observer groups. The further the angle reduced below -

4° or increased from 36°, the more unattractive it was perceived to be, with -8° and below

and 39° and above being perceived as very and extremely unattractive by all observer groups.

It thereby appears that a NLA-UC angle of 12 to 24° is perceived as the most attractive, and

between 8 to 30° is deemed acceptable. Angles in the range -4 to 4° and 33 to 36° are deemed

from acceptable to slightly unattractive, with any values towards the apparently ideal 24°

being more unattractive. Angles above 39° or below -8° are perceived as very/extremely

unattractive by all groups, with greater deviations leading to progressively reduced

perceptions of attractiveness.

In terms of desire for surgical correction, the results of this investigation indicate that

clinicians were generally least likely to suggest surgery for varying degrees of NLA-UC

angle. In addition, there appears to be a high degree of agreement amongst clinicians, with

the repeatability of the clinician group’s assessment being excellent. The reason for this may

be conjectured to be that clinicians develop higher critical capabilities because of their

training. The patient group also demonstrated relatively good reliability and agreement,

which again may be conjectured to be that the very existence of a facial deformity may lead

to patients developing a greater sensitivity to noticeable differences in facial appearance from

the norm. In terms of threshold values of desire for surgery, for patients the threshold value of

desire for surgery was 33° and above and -8° and below, and for both clinicians and lay

people the threshold value was 36° and above and -8° and below.

10

It is generally acknowledged that, as with most facial parameters, the nasolabial angle has a

range of normal individual variability. A number of authorities have provided “ideal” values

for the nasolabial angle, based on anecdotal evidence and the “good eye” of the respective

surgeon. For example, Powell and Humphreys [13] described a range of 90-120 degrees,

though in their “aesthetic triangle” they provided a range of 90-105 degrees. Davidson and

Murakami [14] provided an angle of 90° in men as ideal, with a range of 100-105° in women.

Guyuron [15] described a range of 90-100° in men and 100-108° in women. Rohrich et al.

[16] described a range of 90-95° in men and 95-100° in women. Orten and Hilger [17]

described a range of 90-95° men and 95-115° in women. Papel and Capone [18] described a

range of 90-100° in men and 100-110° in women. Average values, based on anthropometric

studies by Farkas et al. [8], for adult Caucasians are 100 ± 12° in males and 104 ± 10° in

females. There is ethnic variability, and average values for a Chinese population have been

provided as 87 ± 12° in males and 89 ± 11° in females, and in an African-American

population as 72 ± 15° in males and 74 ± 15° in females [10]. None of the authorities

provided separate values for the upper and lower components of the nasolabial angle.

It is important to bear in mind that the profile silhouette image created was based on

Caucasian proportions and normative values. Therefore, it is not generalizable to different

ethnic groups and populations. As such, it may not be directly relevant to other ethnic groups,

through it does provide an insight into how different ethnic groups view Caucasian faces. It

would be interesting to repeat the study using images from different ethnic groups.

It is important to bear in mind that perceived nasal profile attractiveness depends to a great

extent on the size, morphology and position of the nose relative to its neighbouring structures

[1]. For example, inadequate chin prominence may create the appearance of excessive nasal

prominence. Further research is required to substantiate the influence of the chin on perceived

nasal aesthetics, and vice versa.

11

The interplay between the inclination of the upper lip and the inclination of the nasal

columella is an important determinant in clinical diagnosis and treatment planning. The

inclination of the upper lip will partly depend on the sagittal position of the anterior maxilla

and the inclination of the maxillary incisor teeth. Alteration in either parameter may affect the

nasal columella inclination or nasolabial angle, e.g. maxillary advancement at the Le Fort I

level tends to elevate the nasal tip, whereas retroclination of proclined maxillary incisors will

reduce the upper lip inclination, thereby increasing the lower component of the nasolabial

angle. The impact of such changes on the upper component of the nasolabial angle suggests

that rhinoplastic correction is, more often than not, preferentially undertaken after orthodontic

and/or orthognathic procedures involving the anterior maxillary region.

5. CONCLUSIONS

The null hypotheses being studied were rejected. There does appear to be an effect of the type

and degree/severity of the deviation of the upper component of the nasolabial angle on

perceived attractiveness and desire for surgery.

The results of the present investigation demonstrate that a NLA-UC angle of between 12° to

24° is ideal, with a range of 8° to 30° deemed acceptable. Angles above or below this range,

up to -4° and 36° are perceived as slightly unattractive, and anything outside the range of -4°

to 36° is deemed very unattractive.

In terms of threshold values of desire for surgery, for patients the threshold value of desire for

surgery was 33° and above and -8° and below, and for both clinicians and lay people the

threshold value was 36° and above and -8° and below.

There is a difference in the perception of orthognathic patients, laypeople and clinicians.

Patients appear to be more critical than lay and clinician groups. This stresses the

12

importance of using patients as observers, as well as laypeople and

clinicians, in facial attractiveness research.

13

6. REFERENCES

1. Naini FB: Facial Aesthetics: Concepts and Clinical Diagnosis. Oxford, Wiley-Blackwell,

2011.

2. Pearson DC, Adamson PA: The ideal nasal profile: rhinoplasty patients vs. the general

public. Arch Facial Plast Surg 6:257, 2004.

3. Ioi H, Nakata S, Nakasima A, Counts A: Effect of facial convexity on antero-posterior

lip positions of the most favored Japanese facial profiles. Angle Orthod 75:326, 2005.

4. Naini FB, Donaldson ANA, McDonald F, Cobourne MT: Assessing the influence of chin

prominence on perceived attractiveness in the orthognathic patient, layperson and

clinician. Int J Oral Maxillofac Surg 41:839, 2012.

5. Farkas LG, Katic MJ, Hreczko TA, Deutsch C, Munro IR: Anthropometric proportions

in the upper lip-lower lip-chin area of the lower face in young white adults. Am J Orthod

86:52, 1984.

6. Farkas LG, Hreczko TA, Kolar JC, Munro IR: Vertical and horizontal proportions of the

face in young adult North American Caucasians: revision of neoclassical canons. Plast

Reconstr Surg 75:328, 1985.

7. Farkas LG, Sohm P, Kolar JC, Katic MJ, Munro IR: Inclinations of the facial profile: art

versus reality. Plast Reconstr Surg 75:509, 1985.

8. Farkas LG, Kolar JC, Munro IR: Geography of the nose: a morphometric study.

Aesthetic Plast Surg 10:191, 1986.

14

9. Farkas LG, Kolar JC: Anthropometrics and art in the aesthetics of women's faces. Clin

Plast Surg 14:599, 1987.

10. Farkas LG: Anthropometry of the attractive North American Caucasian face, in Farkas

LG (ed.): Anthropometry of the head and face (2nd Ed). New York, Raven Press, 1994.

11. Langlois, J.H., Kalakanis, L., Rubenstein, A.J., Larson, A., Hallam, M. and Smoot, M:

Maxims or myths of beauty? A meta-analytic and theoretical review. Psychol Bull

126:390, 2000.

12. Naini FB, Cobourne MT, Mcdonald F, Donaldson AN: The influence of craniofacial to

standing height proportion on perceived attractiveness. Int J Oral Maxillofac Surg

37:877, 2008.

13. Powell N, Humphreys B: Proportions of the Aesthetic Face. New York, Thieme, 1984.

14. Davidson TM, Murakami WT: Rhinoplasty planning: aesthetic concepts, dynamics, and

facial reconstruction. 2nd ed. Washington, DC: American Academy of Otolaryngology –

Head and Neck Surgery Foundation, 1986.

15. Guyuron B: Nasal proportions, in Gruber RP, Peck GC (Eds.): Rhinoplasty: State of the

Art. St Louis, Mosby, 1993.

16. Rohrich RJ, Muzaffar AR, Oneal RM: Preferred anatomic terms for rhinoplasty, in

Gunter JP, Rohrich RJ, Adams WP (Eds.): Dallas Rhinoplasty: Nasal surgery by the

master. St Louis, Quality Medical Publishing, 2002.

17. Orten SS, Hilger PA: Facial analysis of the rhinoplasty patient, in Papel ID et al. (Eds.):

Facial Plastic and Reconstructive Surgery (2nd ed.). New York, Thieme, 2002.

15

18. Papel ID, Capone RB: Facial proportions and esthetic ideals, in Behrbohm H, Tardy Jr

ME: Essentials of septorhinoplasty. New York, Thieme, 2004.

16

Figure Captions

Figure 1 Upper component of the nasolabial angle: NLA, nasolabial angle; UC, upper

component of the nasolabial angle; TrH, true horizontal line; Sn, subnasale.

Figure 2 Upper component of the nasolabial angle of the idealized profile image was

altered incrementally, creating a series of images.

Figure 3 An example of an image viewed by study observers on the monitor during

data collection.

Figure 4 Clinician data in graphical form with a cubic curve fitted to the data (r2=0.85),

showing that angles 8° and 24° had the highest ranking

Table Captions

Table 1 Observer demographics

Table 2 Median attractiveness observer ratings on the Likert scale

Table 3 Data in rank order from most to least attractive (clinician ranking first)

Table 4 Proportion expressed as a percentage of each observer group suggesting a

desire for surgery in rank order

17