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Effect of lower facial vertical proportion on facial attractiveness in Japanese
orthodontic waves 65 (2006) 161–165
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/odw
Research paper
Effect of lower facial vertical proportion on facial attractiveness in Japanese Hideki Ioi a,*, Hiroko Yasutomi a, Shunsuke Nakata a, Akihiko Nakasima a, Amy L. Counts b a b
Department of Orthodontics, Faculty of Dentistry, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Dental School of Orthodontics, Jacksonville University, Jacksonville, FL, USA
article info
abstract
Article history:
The purpose of this study was to assess the range of the top three most-favored facial
Received 29 August 2006
profiles for each sex from a series of varying lower facial vertical proportion, and to evaluate
Received in revised form
clinically acceptable facial profiles for Japanese adults. Silhouettes of average male and
8 November 2006
female profiles were constructed from the profiles of 30 Japanese males and females with
Accepted 21 November 2006
normal occlusions. Lower facial vertical proportions were increased or decreased by inter-
Published on line 13 December 2006
vals of 5% of Sn–Me0 for each sex from the average profile. Forty-one orthodontists and 50 dental students were asked to select the 3 most-favored, well-balanced profiles for each sex.
Keywords:
They were also asked to indicate whether they would seek surgical orthodontic treatment
Facial profile preference
for each of the shorter or longer lower facial profiles if those images represented their own
Lower facial vertical proportion
profile. For male profiles, both the orthodontists and dental students chose the average
Facial silhouette
profile as the most-favored. For female profiles, the dental students chose a slightly shorter
Japanese
lower facial as the most-favored profile while the orthodontists chose the average profile. The dental students chose shorter lower facial profiles as more acceptable than longer lower facial profiles for females ( p < 0.05). These findings suggest that an average lower facial profile tended to be favored overall by Japanese people, whereas for females a slightly shorter lower facial profile was favored by young adults. # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved.
1.
Introduction
When orthodontists develop a treatment plan, they utilize the established normal values for each ethnic group. For example, the average antero-posterior (A-P) lip position in Japanese adults is regarded to be relatively protrusive compared to that of Caucasians [1]. It is important to consider the perceptions of a well balanced, pleasing profile, because the goal of orthodontic treatment is not only to achieve a
functional occlusion, but to also create an aesthetic profile [2]. In some western countries, a normal facial profile with an average lower facial vertical proportion was rated to be the most attractive [3–5], and a reduced lower facial vertical proportion was rated as significantly more acceptable than corresponding images with an increased lower facial proportion [5–7]. However, it has not been reported about the effect of lower facial vertical proportion on facial attractiveness in Japanese people.
* Corresponding author. Tel.: +81 92 642 6462; fax: +81 92 642 6398. E-mail address: [email protected] (H. Ioi). 1344-0241/$ – see front matter # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved. doi:10.1016/j.odw.2006.11.002
162
orthodontic waves 65 (2006) 161–165
There are many patients that are considered borderline in determining whether a case warrants surgical or orthodontic camouflage treatment. In these cases, although cephalometric analysis can be useful, the decision-making process is largely based on subjective clinical judgment from the facial profile point of view. Although there are a few reports concerning the facial preference of the non-experts to the lower facial vertical proportion for the Caucasian people [5,8], there are few reports regarding them for Japanese. The purpose of this study was to assess and determine the range of the top three most-favored facial profiles of each sex from a series of silhouettes of varying lower facial vertical proportion, and to evaluate the clinically acceptable facial profiles for Japanese adults.
2.
Materials and methods
2.1.
Construction of the average Japanese facial profile
Average Japanese silhouettes were constructed from 30 cephalometric radiographs (15 males and 15 females) of Japanese adults aged 22–26 years. Inclusion criteria for this study was an ANB angle between 28 and 58, a normal occlusion with minor or no crowding, all teeth present except third molars, no previous orthodontic treatment, and no prosthetic replacement of teeth. The average Japanese profile silhouettes were constructed for males and females, respectively. The detailed process of constructing the average profile and reliability of the measurements was reported in previous studies [9,10]. The values of the soft tissue measurements for the average profile were found to be within one standard deviation of the Japanese cephalometric norms [11].
2.2.
Construction of a series of profiles
The reference points to construct each silhouette are shown in Fig. 1. The changes in lower facial vertical proportion were generated by altering the vertical position of Sn–Me0 . The proportion of Sn–St and St–Me0 was maintained in all the images. Lower facial vertical proportions were increased or decreased by intervals of 5% of Sn–Me0 for each sex from the average profile. In each silhouette, the average lip protrusion positions were maintained in relation to Sn–Pg0 for males and females respectively. The soft tissue outlines above Sn and below Pg0 were not altered and were identical for all silhouettes. The profile with the average lower facial vertical proportion (no. 6) occupied the middle position in the series. Left to right, profile no. 1 depicted the shortest lower facial vertical proportion, and no. 11, the longest lower facial vertical proportion (Fig. 2). Facial silhouettes were chosen for rating facial profiles, rather than facial photos, to avoid subjective considerations [12,13].
2.3.
Fig. 1 – Soft tissue reference points and measuring items: (1) upper facial height (G0 –Sn); (2) lower facial height (Sn– Me0 ); (3) nasolabial angle; (4) Z-angle.
top three most-favored profiles for each sex. They were also asked to indicate, using the response choices of yes or no, whether they would seek surgical orthodontic treatment for each of the short or long lower facial profiles if those images represented their own profile.
2.4.
Statistical analysis
The Fisher’s exact probability tests were used to compare the differences in the scores between the top three most-favored profiles and the other profiles, and to compare the proportion of judges seeking surgical treatment between the short lower facial vertical proportion (nos. 1–5) and the long lower facial vertical proportion (nos. 7–11) profiles. A probability of less than 0.05 was considered as statistically significant.
Profile raters
The profile raters were 41 Japanese orthodontists (20 males; 21 females, age 33.0 9.5 years), and 50 senior dental students (29 males; 21 females, age 23.6 2.3 years) from Kyushu University in Fukuoka, Japan. They were asked to choose the
Fig. 2 – Series of 11 profiles rated by orthodontists and dental students for males (upper row) and females (lower row).
163
orthodontic waves 65 (2006) 161–165
Fig. 3 – Distribution of most-favored profiles: (A) orthodontists and dental students rating males and (B) orthodontists and dental students rating females.
Fig. 4 – Proportion of judges seeking surgical treatment: (A) orthodontists and dental students rating males and (B) orthodontists and dental students rating females.
3.
Results
3.1.
The most-favored Japanese facial profiles
proportion (upper facial height/lower facial height), nasolabial angle and Z-angle (Table 1 and Fig. 1). For males rated by both the orthodontists and dental students, the most-favored lower facial vertical proportion values ranged from 1.01 to 1.11. The most favored nasolabial angle values ranged from 93.08 to 95.08. The most favored Zangle values ranged from 68.08 to 70.08 (Table 1). For females rated by the orthodontists, the most-favored lower facial vertical proportion values ranged from 1.04 to 1.14. The most favored nasolabial angle values ranged from 99.08 to 101.08. The most favored Z-angle values ranged from 66.08 to 68.08 (Table 1). For females rated by the dental students, the most-favored lower facial vertical proportion values ranged from 1.09 to 1.19. The most favored nasolabial angle values ranged from 98.08 to 100.08. The most favored Z-angle values ranged from 65.08 to 67.08 (Table 1).
For the orthodontist raters, the top three most-favored male profiles were 6, 5, and 7, respectively (Fig. 3A), while the mostfavored female profiles were 6, 7, and 5, respectively (Fig. 3B). The scores for these top three profiles for males and females were significantly larger than the other profiles ( p < 0.05). For the dental students, the three most-favored male profiles were 6, 7, and 5, respectively (Fig. 3A), while the most-favored female profiles were 5, 6, and 4, respectively (Fig. 3B). The scores for these top three profiles for males and females were significantly larger than the other profiles ( p < 0.05). From these most-favored profiles, the range of the following soft tissue measurements was determined: lower facial vertical
Table 1 – Range of preferred Japanese facial profile values rated by orthodontists and dental students Variables
0
0
UFH/LFH (G –Sn/Sn–Me ) ratio Nasolabial angle (Cm–Sn–Ls) (8) Z-angle (chin/lip line to FH plane) (8)
Orthodontists (n = 41)
Dental students (n = 50)
Male (n = 20)
Female (n = 21)
Male (n = 29)
1.01–1.11 93.0–95.0 68.0–70.0
1.04–1.14 99.0–101.0 66.0–68.0
1.01–1.11 93.0–95.0 68.0–70.0
UFH: upper facial height and LFH: lower facial height.
Female (n = 21) 1.09–1.19 98.0–100.0 65.0–67.0
164
3.2.
orthodontic waves 65 (2006) 161–165
The clinically acceptable facial profiles
For males, 59% of the orthodontists and 66% of the dental students would seek surgical treatment if their profiles were represented by no. 11, with a long lower facial profile (Fig. 4A). On the other hand, 83% of the orthodontists and 68% of the dental students would seek surgical treatment if their profiles were represented by no. 1, with a short lower facial profile (Fig. 4A). There was no significant difference in the proportion of judges seeking treatment between short lower facial (nos. 1– 5) and long lower facial (nos. 7–11) profiles for both the orthodontists and dental students. For females, 66% of the orthodontists and 76% of the dental students would seek surgical treatment if their profiles were represented by no. 11, a long lower facial profile (Fig. 4B). On the other hand, 81% of the orthodontists and 54% of the dental students would seek surgical treatment if their profiles were represented by no. 1, a short lower facial profile (Fig. 4B). Although there was no significant difference for the number of orthodontists seeking surgical treatment between short and long lower facial profiles, the long lower facial profiles showed a significantly larger number of dental students seeking surgical treatment than short lower facial profiles ( p < 0.05).
4.
Discussion
The objectives of orthodontic treatment are to achieve facial balance, through stabilization of the dentition, and the production of pleasing facial and dental aesthetics [14]. Therefore, it is important to identify and define the characteristics of a pleasing, well-balanced face, as well as those of a functioning occlusion. Our predecessors, including philosophers and artists, attempted to define beauty. However, it was difficult to determine the standards of beauty, because of the tremendous variations among people occupying different racial groups [14]. We have previously reported that Japanese orthodontists and young adults prefer a more retruded lip position than the average Japanese lip position, even though their profiles have historically been characterized by more protruded lip features [9,10,15]. These studies suggested that cephalometric values outside the normal range should be considered when tailoring an individual treatment plan. However, there are few reports on lower facial vertical proportion for facial attractiveness in Japanese people. Our hypothesis is that the perception of facial preference may be approximate to the average profile on the basis of lower facial vertical proportion. Perceptions may also differ regarding acceptable facial aesthetics between short and long lower facial profiles. Although there are ample reports showing the facial preference to the lower facial vertical proportion for the Caucasians [3–8], the ethnic difference might lead to the different preference. This study was particularly aimed to determine the facial preference of Japanese to the lower facial vertical proportion. The raters selected for this study were the orthodontists and dental students. We considered each of the two groups as the experts and non-experts group, respectively. Although the opinion of dental students may not represent lay opinion precisely, we grouped them as the non-experts, because the
dental students who participated in this study received no education about the evaluation of orthodontic facial appearance.
4.1.
The most-favored Japanese facial profiles
If the raters in this study chose the average profile as the wellbalanced one, they should have selected no. 6. Both the orthodontists and dental students chose no. 6 as the mostfavored profile for males. Similarly, in some western countries, the normal facial profile with the average lower facial vertical proportion was rated as to be the most attractive [3–5]. This finding suggests that for males, it would be helpful to use the Japanese cephalometric normal values when evaluating lower facial vertical proportion. However, for females, the dental students chose no. 5 as the most-favored profile while the orthodontists chose no. 6. The judgement of facial attractiveness has been thought to depend on an individual’s personal taste [16]. However, psychologists reported that individuals are inclined to prefer neutral-looking faces representing the mathematical average of faces within the studied population [17,18]. In this study, although this concept is applicable to facial preference for males and females rated by the orthodontists, it was not the case for females rated by the dental students, who prefer a slightly shorter lower facial skeletal relationship. According to a study by Perrett et al. [19], the faces people found to be most attractive were deliberately exaggerated computer-generated images, depicting higher cheek bones, a thinner jaw and larger eyes than the average face. These facial features correspond with the soft tissue facial pattern of young adults. Tallgren [20] reported an increase in skeletal facial height with advancing age. Fedok [21] also stated that with age the soft tissue below the chin lost elasticity and dropped creating the characteristic jowl that resulted in an apparent lengthening of the profile. Buss [22] and Peck and Peck [23] suggested that there might be an association between human facial preference and age-related features signalling youthfulness and, by extension, fertility, a powerful evolutionary selection pressure. The facial preference tendency for females rated by the dental students support their proposal, that is, a slightly shorter lower facial vertical height, which equates with a more youthful-looking face, was favored by young adults. For males, the orthodontists and dental students preferred the same ranges of lower facial vertical proportion, nasolabial angle, and Z-angle, respectively. For females, the dental students preferred a slightly shorter lower facial height than the orthodontists, differing by 0.05 in the proportion measurement or 1.08 in the angular measurements. However, these results should be interpreted carefully when evaluating nasolabial angle and Z-angle using silhouettes, because these measuring items would vary secondarily as the lower facial vertical proportion varies.
4.2.
The clinically acceptable facial profiles
For male profiles, there was no significant difference in the acceptable profile between short and long lower facial profiles both for the orthodontists and dental students. However, the dental students chose short lower facial profiles as more
orthodontic waves 65 (2006) 161–165
acceptable than long lower facial profiles for females. Several researchers [8,24–26] reported that clinicians and non-clinicians do not necessarily agree with the facial preference. In this study, we selected the dental students as being representatives of non-experts or young adults. In fact, considering that patients who would seek surgical orthodontic treatment would be young adults, it is important to evaluate the perceptions of non-experts and young adults in determining a surgical orthodontic treatment plan. Knight and Keith [8] suggested that the non-clinician group rating should be used as the standard to reflect lay opinion. Johnston et al. [5] reported that images with a reduced lower facial vertical proportion were significantly less likely to be judged as needing treatment than the images with an increased lower facial vertical proportion in the Caucasian population. Knight and Keith [8] also stated that there was a trend for an increase in the anterior lower face height percentage to be associated with less attractive faces for female subjects when judged by non-clinicians, but no clear trend when assessed by clinicians. They speculated that clinicians and non-clinicians were influenced when ranking the female faces by preferences in, e.g. hair appearance. In this study, these facial expression and personality traits would be excluded, because we evaluated the facial attractiveness using facial silhouettes. Although a distinct tendency for the preference of facial profiles on the lower facial vertical proportion was not found in Japanese males, there might be a universal consensus for the female facial preference, that is, short lower facial profiles were rated as more attractive and acceptable than long lower facial profiles when rated by non-experts and young adults. In this study, we found that in relation to lower facial vertical proportion, an average profile was favored for Japanese males and a slightly shorter lower facial profile was favored for Japanese females by the dental students. Female patients with long lower facial profiles tended to seek surgical orthodontic treatment more often. However, all patients should not be treated to look alike. Some patients might not want their facial features altered to those considered to be well balanced by others. Different racial groups have different perceptions of what is well balanced and attractive.
[3]
[4] [5]
[6] [7]
[8] [9]
[10]
[11]
[12] [13]
[14] [15]
[16]
[17] [18]
[19]
5.
Conclusions
1. For male profiles, both the orthodontists and dental students chose the average profile as the most-favored. 2. For female profiles, the dental students chose a slightly shorter lower facial profile as the most-favored, while the orthodontists chose the average profile as the most-favored.
[20]
[21] [22] [23] [24]
references [25] [1] Iwasawa T, Moro T, Nakamura K. Considerations of the soft tissues of normal occlusal subjects with good facial and Tweed triangle. J Jpn Orthod 1974;33:99–104. [2] Sarver DM, Proffit WR, Ackerman JL. Diagnosis and treatment planning in orthodontics. In: Graber TM,
[26]
165
Vanarsdall Jr RL, editors. Orthodontics current principles and techniques. 3rd ed., St. Louis: Mosby; 2000. p. 3–115. Sergl HG, Zentner A, Krause G. An experimental study of the esthetic effect of facial profiles. J Orofac Orthop 1998;59:116–26. Edler RJ. Background considerations to facial aesthetics. J Orthod 2001;28:159–68. Johnston C, Hunt O, Johnston CD, Burden D, Stevenson M, Hepper P. The influence of lower facial vertical proportion on facial attractiveness. Eur J Orthod 2005; 27:349–54. De Smith A, Dermaut L. Soft-tissue profile preference. Am J Orthod 1984;86:67–73. Michiels G, Sather AH. Determinants of facial attractiveness in a sample of white women. Int J Adult Orthod Orthognath Surg 1994;9:95–103. Knight H, Keith O. Ranking facial attractiveness. Eur J Orthod 2005;27:340–8. Ioi H, Nakata S, Nakasima A, Counts AL. Anteroposterior lip positions of the most-favored Japanese facial profiles. Am J Orthod Dentofacial Orthop 2005;128:206–11. Ioi H, Nakata S, Nakasima A, Counts A. Effect of facial convexity on antero-posterior lip positions of the mostfavored Japanese facial profiles. Angle Orthod 2005;75:326– 32. Alcalde R, Jinno T, Orsini G, Sasaki A, Sugiyama RM, Matsumura T. Soft tissue cephalometric norms in Japanese adults. Am J Orthod Dentofacial Orthop 2000;118:84–9. Foster FJ. Profile preferences among diversified groups. Angle Orthod 1973;43:34–40. Czarnecki ST, Nanda RS, Currier GF. Perceptions of a balanced facial profile. Am J Orthod Dentofacial Orthop 1993;104:180–7. Burstone CJ, Marcotte MR. Problem solving in orthodontics. Carol Stream, Quintessence; 2000, p. 98–120. Ishii K, Yamaki M, Saito I, Kaloust S, Hanada K. WWWbased investigations of profile preferences among Caucasians and Japanese. Orthod Waves 1998;57:425–30. Albino JE, Tedesco LA. Esthetic need for orthodontic treatment. In: Melsen B, editor. Current contriversies in orthodontics. Chicago: Quintessence Publishing; 1991. p. 11–24. Langlois JH, Roggman LA. Attractive facials are only average. Psychol Sci 1990;1:115–21. Langlois JH, Roggman LA, Musselman L. What is average and what is not average about attractive facials. Psychol Sci 1994;5:214–20. Perrett DI, May KA, Yoshikawa S. Facial shape and judgments of female attractiveness. Nature 1994;368:239– 42. Tallgren A. Changes in adult facial height due to ageing, wear and loss of teeth and prosthetic dentistry. Acta Odontol Scand 1957;15:24. Fedok FG. The ageing facial. Facial Plast Surg 1996;12:107– 15. Buss DM. The strategies of human mating. Am Sci 1994;82:238–47. Peck S, Peck L. Selected aspects of the art and science of facial esthetics. Semin Orthod 1995;1:105–26. Prahl-Andersen B, Boersma H, van der Linden FPGM, Moore AW. Perceptions of dentofacial morphology by laypersons, general dentists, and orthodontists. J Am Dent Assoc 1979;98:209–12. Shaw WC. The influence of children’s dentofacial appearance on their social attractiveness as judged by peers and lay adults. Am J Orthod 1981;79:399–415. Phillips C, Griffin T, Bennett E. Perception of facial attractiveness by patients, peers, and professionals. Int J Adult Orthod Orthognath Surg 1995;10:127–35.
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/odw
Research paper
Effect of lower facial vertical proportion on facial attractiveness in Japanese Hideki Ioi a,*, Hiroko Yasutomi a, Shunsuke Nakata a, Akihiko Nakasima a, Amy L. Counts b a b
Department of Orthodontics, Faculty of Dentistry, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Dental School of Orthodontics, Jacksonville University, Jacksonville, FL, USA
article info
abstract
Article history:
The purpose of this study was to assess the range of the top three most-favored facial
Received 29 August 2006
profiles for each sex from a series of varying lower facial vertical proportion, and to evaluate
Received in revised form
clinically acceptable facial profiles for Japanese adults. Silhouettes of average male and
8 November 2006
female profiles were constructed from the profiles of 30 Japanese males and females with
Accepted 21 November 2006
normal occlusions. Lower facial vertical proportions were increased or decreased by inter-
Published on line 13 December 2006
vals of 5% of Sn–Me0 for each sex from the average profile. Forty-one orthodontists and 50 dental students were asked to select the 3 most-favored, well-balanced profiles for each sex.
Keywords:
They were also asked to indicate whether they would seek surgical orthodontic treatment
Facial profile preference
for each of the shorter or longer lower facial profiles if those images represented their own
Lower facial vertical proportion
profile. For male profiles, both the orthodontists and dental students chose the average
Facial silhouette
profile as the most-favored. For female profiles, the dental students chose a slightly shorter
Japanese
lower facial as the most-favored profile while the orthodontists chose the average profile. The dental students chose shorter lower facial profiles as more acceptable than longer lower facial profiles for females ( p < 0.05). These findings suggest that an average lower facial profile tended to be favored overall by Japanese people, whereas for females a slightly shorter lower facial profile was favored by young adults. # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved.
1.
Introduction
When orthodontists develop a treatment plan, they utilize the established normal values for each ethnic group. For example, the average antero-posterior (A-P) lip position in Japanese adults is regarded to be relatively protrusive compared to that of Caucasians [1]. It is important to consider the perceptions of a well balanced, pleasing profile, because the goal of orthodontic treatment is not only to achieve a
functional occlusion, but to also create an aesthetic profile [2]. In some western countries, a normal facial profile with an average lower facial vertical proportion was rated to be the most attractive [3–5], and a reduced lower facial vertical proportion was rated as significantly more acceptable than corresponding images with an increased lower facial proportion [5–7]. However, it has not been reported about the effect of lower facial vertical proportion on facial attractiveness in Japanese people.
* Corresponding author. Tel.: +81 92 642 6462; fax: +81 92 642 6398. E-mail address: [email protected] (H. Ioi). 1344-0241/$ – see front matter # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved. doi:10.1016/j.odw.2006.11.002
162
orthodontic waves 65 (2006) 161–165
There are many patients that are considered borderline in determining whether a case warrants surgical or orthodontic camouflage treatment. In these cases, although cephalometric analysis can be useful, the decision-making process is largely based on subjective clinical judgment from the facial profile point of view. Although there are a few reports concerning the facial preference of the non-experts to the lower facial vertical proportion for the Caucasian people [5,8], there are few reports regarding them for Japanese. The purpose of this study was to assess and determine the range of the top three most-favored facial profiles of each sex from a series of silhouettes of varying lower facial vertical proportion, and to evaluate the clinically acceptable facial profiles for Japanese adults.
2.
Materials and methods
2.1.
Construction of the average Japanese facial profile
Average Japanese silhouettes were constructed from 30 cephalometric radiographs (15 males and 15 females) of Japanese adults aged 22–26 years. Inclusion criteria for this study was an ANB angle between 28 and 58, a normal occlusion with minor or no crowding, all teeth present except third molars, no previous orthodontic treatment, and no prosthetic replacement of teeth. The average Japanese profile silhouettes were constructed for males and females, respectively. The detailed process of constructing the average profile and reliability of the measurements was reported in previous studies [9,10]. The values of the soft tissue measurements for the average profile were found to be within one standard deviation of the Japanese cephalometric norms [11].
2.2.
Construction of a series of profiles
The reference points to construct each silhouette are shown in Fig. 1. The changes in lower facial vertical proportion were generated by altering the vertical position of Sn–Me0 . The proportion of Sn–St and St–Me0 was maintained in all the images. Lower facial vertical proportions were increased or decreased by intervals of 5% of Sn–Me0 for each sex from the average profile. In each silhouette, the average lip protrusion positions were maintained in relation to Sn–Pg0 for males and females respectively. The soft tissue outlines above Sn and below Pg0 were not altered and were identical for all silhouettes. The profile with the average lower facial vertical proportion (no. 6) occupied the middle position in the series. Left to right, profile no. 1 depicted the shortest lower facial vertical proportion, and no. 11, the longest lower facial vertical proportion (Fig. 2). Facial silhouettes were chosen for rating facial profiles, rather than facial photos, to avoid subjective considerations [12,13].
2.3.
Fig. 1 – Soft tissue reference points and measuring items: (1) upper facial height (G0 –Sn); (2) lower facial height (Sn– Me0 ); (3) nasolabial angle; (4) Z-angle.
top three most-favored profiles for each sex. They were also asked to indicate, using the response choices of yes or no, whether they would seek surgical orthodontic treatment for each of the short or long lower facial profiles if those images represented their own profile.
2.4.
Statistical analysis
The Fisher’s exact probability tests were used to compare the differences in the scores between the top three most-favored profiles and the other profiles, and to compare the proportion of judges seeking surgical treatment between the short lower facial vertical proportion (nos. 1–5) and the long lower facial vertical proportion (nos. 7–11) profiles. A probability of less than 0.05 was considered as statistically significant.
Profile raters
The profile raters were 41 Japanese orthodontists (20 males; 21 females, age 33.0 9.5 years), and 50 senior dental students (29 males; 21 females, age 23.6 2.3 years) from Kyushu University in Fukuoka, Japan. They were asked to choose the
Fig. 2 – Series of 11 profiles rated by orthodontists and dental students for males (upper row) and females (lower row).
163
orthodontic waves 65 (2006) 161–165
Fig. 3 – Distribution of most-favored profiles: (A) orthodontists and dental students rating males and (B) orthodontists and dental students rating females.
Fig. 4 – Proportion of judges seeking surgical treatment: (A) orthodontists and dental students rating males and (B) orthodontists and dental students rating females.
3.
Results
3.1.
The most-favored Japanese facial profiles
proportion (upper facial height/lower facial height), nasolabial angle and Z-angle (Table 1 and Fig. 1). For males rated by both the orthodontists and dental students, the most-favored lower facial vertical proportion values ranged from 1.01 to 1.11. The most favored nasolabial angle values ranged from 93.08 to 95.08. The most favored Zangle values ranged from 68.08 to 70.08 (Table 1). For females rated by the orthodontists, the most-favored lower facial vertical proportion values ranged from 1.04 to 1.14. The most favored nasolabial angle values ranged from 99.08 to 101.08. The most favored Z-angle values ranged from 66.08 to 68.08 (Table 1). For females rated by the dental students, the most-favored lower facial vertical proportion values ranged from 1.09 to 1.19. The most favored nasolabial angle values ranged from 98.08 to 100.08. The most favored Z-angle values ranged from 65.08 to 67.08 (Table 1).
For the orthodontist raters, the top three most-favored male profiles were 6, 5, and 7, respectively (Fig. 3A), while the mostfavored female profiles were 6, 7, and 5, respectively (Fig. 3B). The scores for these top three profiles for males and females were significantly larger than the other profiles ( p < 0.05). For the dental students, the three most-favored male profiles were 6, 7, and 5, respectively (Fig. 3A), while the most-favored female profiles were 5, 6, and 4, respectively (Fig. 3B). The scores for these top three profiles for males and females were significantly larger than the other profiles ( p < 0.05). From these most-favored profiles, the range of the following soft tissue measurements was determined: lower facial vertical
Table 1 – Range of preferred Japanese facial profile values rated by orthodontists and dental students Variables
0
0
UFH/LFH (G –Sn/Sn–Me ) ratio Nasolabial angle (Cm–Sn–Ls) (8) Z-angle (chin/lip line to FH plane) (8)
Orthodontists (n = 41)
Dental students (n = 50)
Male (n = 20)
Female (n = 21)
Male (n = 29)
1.01–1.11 93.0–95.0 68.0–70.0
1.04–1.14 99.0–101.0 66.0–68.0
1.01–1.11 93.0–95.0 68.0–70.0
UFH: upper facial height and LFH: lower facial height.
Female (n = 21) 1.09–1.19 98.0–100.0 65.0–67.0
164
3.2.
orthodontic waves 65 (2006) 161–165
The clinically acceptable facial profiles
For males, 59% of the orthodontists and 66% of the dental students would seek surgical treatment if their profiles were represented by no. 11, with a long lower facial profile (Fig. 4A). On the other hand, 83% of the orthodontists and 68% of the dental students would seek surgical treatment if their profiles were represented by no. 1, with a short lower facial profile (Fig. 4A). There was no significant difference in the proportion of judges seeking treatment between short lower facial (nos. 1– 5) and long lower facial (nos. 7–11) profiles for both the orthodontists and dental students. For females, 66% of the orthodontists and 76% of the dental students would seek surgical treatment if their profiles were represented by no. 11, a long lower facial profile (Fig. 4B). On the other hand, 81% of the orthodontists and 54% of the dental students would seek surgical treatment if their profiles were represented by no. 1, a short lower facial profile (Fig. 4B). Although there was no significant difference for the number of orthodontists seeking surgical treatment between short and long lower facial profiles, the long lower facial profiles showed a significantly larger number of dental students seeking surgical treatment than short lower facial profiles ( p < 0.05).
4.
Discussion
The objectives of orthodontic treatment are to achieve facial balance, through stabilization of the dentition, and the production of pleasing facial and dental aesthetics [14]. Therefore, it is important to identify and define the characteristics of a pleasing, well-balanced face, as well as those of a functioning occlusion. Our predecessors, including philosophers and artists, attempted to define beauty. However, it was difficult to determine the standards of beauty, because of the tremendous variations among people occupying different racial groups [14]. We have previously reported that Japanese orthodontists and young adults prefer a more retruded lip position than the average Japanese lip position, even though their profiles have historically been characterized by more protruded lip features [9,10,15]. These studies suggested that cephalometric values outside the normal range should be considered when tailoring an individual treatment plan. However, there are few reports on lower facial vertical proportion for facial attractiveness in Japanese people. Our hypothesis is that the perception of facial preference may be approximate to the average profile on the basis of lower facial vertical proportion. Perceptions may also differ regarding acceptable facial aesthetics between short and long lower facial profiles. Although there are ample reports showing the facial preference to the lower facial vertical proportion for the Caucasians [3–8], the ethnic difference might lead to the different preference. This study was particularly aimed to determine the facial preference of Japanese to the lower facial vertical proportion. The raters selected for this study were the orthodontists and dental students. We considered each of the two groups as the experts and non-experts group, respectively. Although the opinion of dental students may not represent lay opinion precisely, we grouped them as the non-experts, because the
dental students who participated in this study received no education about the evaluation of orthodontic facial appearance.
4.1.
The most-favored Japanese facial profiles
If the raters in this study chose the average profile as the wellbalanced one, they should have selected no. 6. Both the orthodontists and dental students chose no. 6 as the mostfavored profile for males. Similarly, in some western countries, the normal facial profile with the average lower facial vertical proportion was rated as to be the most attractive [3–5]. This finding suggests that for males, it would be helpful to use the Japanese cephalometric normal values when evaluating lower facial vertical proportion. However, for females, the dental students chose no. 5 as the most-favored profile while the orthodontists chose no. 6. The judgement of facial attractiveness has been thought to depend on an individual’s personal taste [16]. However, psychologists reported that individuals are inclined to prefer neutral-looking faces representing the mathematical average of faces within the studied population [17,18]. In this study, although this concept is applicable to facial preference for males and females rated by the orthodontists, it was not the case for females rated by the dental students, who prefer a slightly shorter lower facial skeletal relationship. According to a study by Perrett et al. [19], the faces people found to be most attractive were deliberately exaggerated computer-generated images, depicting higher cheek bones, a thinner jaw and larger eyes than the average face. These facial features correspond with the soft tissue facial pattern of young adults. Tallgren [20] reported an increase in skeletal facial height with advancing age. Fedok [21] also stated that with age the soft tissue below the chin lost elasticity and dropped creating the characteristic jowl that resulted in an apparent lengthening of the profile. Buss [22] and Peck and Peck [23] suggested that there might be an association between human facial preference and age-related features signalling youthfulness and, by extension, fertility, a powerful evolutionary selection pressure. The facial preference tendency for females rated by the dental students support their proposal, that is, a slightly shorter lower facial vertical height, which equates with a more youthful-looking face, was favored by young adults. For males, the orthodontists and dental students preferred the same ranges of lower facial vertical proportion, nasolabial angle, and Z-angle, respectively. For females, the dental students preferred a slightly shorter lower facial height than the orthodontists, differing by 0.05 in the proportion measurement or 1.08 in the angular measurements. However, these results should be interpreted carefully when evaluating nasolabial angle and Z-angle using silhouettes, because these measuring items would vary secondarily as the lower facial vertical proportion varies.
4.2.
The clinically acceptable facial profiles
For male profiles, there was no significant difference in the acceptable profile between short and long lower facial profiles both for the orthodontists and dental students. However, the dental students chose short lower facial profiles as more
orthodontic waves 65 (2006) 161–165
acceptable than long lower facial profiles for females. Several researchers [8,24–26] reported that clinicians and non-clinicians do not necessarily agree with the facial preference. In this study, we selected the dental students as being representatives of non-experts or young adults. In fact, considering that patients who would seek surgical orthodontic treatment would be young adults, it is important to evaluate the perceptions of non-experts and young adults in determining a surgical orthodontic treatment plan. Knight and Keith [8] suggested that the non-clinician group rating should be used as the standard to reflect lay opinion. Johnston et al. [5] reported that images with a reduced lower facial vertical proportion were significantly less likely to be judged as needing treatment than the images with an increased lower facial vertical proportion in the Caucasian population. Knight and Keith [8] also stated that there was a trend for an increase in the anterior lower face height percentage to be associated with less attractive faces for female subjects when judged by non-clinicians, but no clear trend when assessed by clinicians. They speculated that clinicians and non-clinicians were influenced when ranking the female faces by preferences in, e.g. hair appearance. In this study, these facial expression and personality traits would be excluded, because we evaluated the facial attractiveness using facial silhouettes. Although a distinct tendency for the preference of facial profiles on the lower facial vertical proportion was not found in Japanese males, there might be a universal consensus for the female facial preference, that is, short lower facial profiles were rated as more attractive and acceptable than long lower facial profiles when rated by non-experts and young adults. In this study, we found that in relation to lower facial vertical proportion, an average profile was favored for Japanese males and a slightly shorter lower facial profile was favored for Japanese females by the dental students. Female patients with long lower facial profiles tended to seek surgical orthodontic treatment more often. However, all patients should not be treated to look alike. Some patients might not want their facial features altered to those considered to be well balanced by others. Different racial groups have different perceptions of what is well balanced and attractive.
[3]
[4] [5]
[6] [7]
[8] [9]
[10]
[11]
[12] [13]
[14] [15]
[16]
[17] [18]
[19]
5.
Conclusions
1. For male profiles, both the orthodontists and dental students chose the average profile as the most-favored. 2. For female profiles, the dental students chose a slightly shorter lower facial profile as the most-favored, while the orthodontists chose the average profile as the most-favored.
[20]
[21] [22] [23] [24]
references [25] [1] Iwasawa T, Moro T, Nakamura K. Considerations of the soft tissues of normal occlusal subjects with good facial and Tweed triangle. J Jpn Orthod 1974;33:99–104. [2] Sarver DM, Proffit WR, Ackerman JL. Diagnosis and treatment planning in orthodontics. In: Graber TM,
[26]
165
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