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Anteroposterior lip positions of the most-favored Japanese facial profiles
ORIGINAL ARTICLE
Anteroposterior lip positions of the mostfavored Japanese facial profiles Hideki Ioi,aⴱ Shunsuke Nakata,b Akihiko Nakasima,c and Amy L. Countsd Fukuoka, Japan, and Oklahoma City, Okla Introduction: Soft tissue analysis is a basic tool in planning orthodontic treatment. However, the components of a well-balanced Japanese facial profile have not yet been established. The purpose of this study was to assess the most-favored or most well-balanced profile from a series of facial silhouettes with varying anteroposterior lip positions by a group of Japanese orthodontists and a group of young adult Japanese dental students. Methods: Average female and male profiles were constructed from the profiles of 30 Japanese men and women with normal occlusions. The lips in each average profile were protruded or retruded in 1-mm increments, and the 13 images were arranged with the average profile in the center. Forty two orthodontists and 42 dental students were asked to select the 3 most-favored, well-balanced profiles for each sex and rank them in order of preference. Results: Both the orthodontists and the students preferred a profile with slightly retruded lips. The dental students favored a more retruded lip position for women. The least-favored profile was the most protrusive. Conclusions: These findings suggest that Japanese orthodontists and young adults prefer a retruded profile, even though Japanese profiles have historically been characterized by more convex facial features. (Am J Orthod Dentofacial Orthop 2005;128:206-11)
T
reatment-planning goals for orthodontic treatment and orthognathic surgery are based on established normal values for each ethnic group. For example, the average anteroposterior lip position in Japanese adults is regarded as relatively more protrusive to that of white people.1 The perceptions of nonorthodontists should be considered in determining a well-balanced, pleasant profile, because the goals of orthodontic treatment are not only to achieve a functional occlusion, but also to create an esthetic profile.2 Soft tissue analyses of wellbalanced Japanese faces have been previously conducted3-14 from the 1950s to the 1970s.3-10 However, there are no studies of profiles evaluated by young adults who could become orthodontic patients. At the present time, young adults experience much exposure to mass media–ie, the Internet and worldwide communication and travel. The perception of a pleasa
Assistant professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. b Associate professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. c Professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. d Associate professor, Department of Orthodontics, College of Dentistry, University of Oklahoma, Oklahoma City. Reprint requests to: Hideki Ioi, Department of Orthodontics, Faculty of Dentistry, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; e-mail, [email protected]. Submitted, December 2003; revised and accepted, April 2004. 0889-5406/$30.00 Copyright © 2005 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2004.04.030
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ing facial profile might be changing because of these international influences. In light of these rapid developments, this study aimed to determine the perceptions of Japanese orthodontists and young adult Japanese dental students of well-balanced, pleasing profiles. Facial silhouettes were chosen for rating facial profiles, rather than facial photos, to avoid subjective considerations.15,16 The purpose of this study was to assess and determine the range of soft tissue anteroposterior lip position of the top 3 mostfavored, well-balanced profiles of each sex from a series of varying lip positions in facial silhouettes. MATERIAL AND METHODS
Average Japanese silhouettes were constructed from 30 cephalometric radiographs (15 men and 15 women) of adults aged 22 to 26 years. Inclusion criteria for this study were an ANB angle between 2° and 5°, a normal occlusion with minor or no crowding, all teeth present except third molars, no previous orthodontic treatment, and no prosthetic replacement of teeth. All lateral cephalometric radiographs were taken with the teeth in maximum intercuspation in a cephalostat oriented to the Frankfort horizontal plane. The radiographs were taken with a DR-15523HC (SSR-2B) cephalostat (Hitachi Medical Corporation, Tokyo, Japan) and exposed at 100 kV, 10 mA. All radiographs were traced by hand on matte acetate sheets and digitized on a personal computer
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To assess method error, 10 cases were randomly selected and traced at 3 separate times. One-way analysis of variance, used to test the equality of means for the cephalometric measurements, suggested that it was done consistently. Mean scores for the soft tissue measurements (P ⫽ .82) did not significantly differ among the 3 separate measurements. The method error can be considered negligible. Series of 13 profiles were developed for men and women (Fig 2). The average profile7 was in the center. The lips were protruded or retruded in 1-mm increments from the average profile, and the lip positions were changed parallel to the Frankfort horizontal plane. Profile 1 is the most retrusive, and 13 is the most protrusive. The profile raters were 42 Japanese orthodontists (20 men, aged 38.0 ⫾ 10.3 years; 22 women, aged 27.6 ⫾ 2.3 years), and 42 dental students (30 men, aged 24.6 ⫾ 1.9 years; 12 women, aged 25.1 ⫾ 2.7 years). They were asked to choose the top 3 most-favored profiles and rank them, with number 1 as the best. They were also asked to choose the least-favored profile. RESULTS
Fig 1. Soft tissue cephalometric reference points and analysis: 1, angle of nasal prominence; 2, collumellar length angle; 3, nasal tip angle; 4, nasolabial angle (Cm-Sn-Ls); 5, upper lip protrusion (Ls to Sn-Pg’); 6, lower lip protrusion (Li to Sn-Pg’); 7, inferior labial sulcus angle; 8, facial convexity (G’-Sn-Pg’); 9, Z-angle (chin/ lip line to FH plane).
by an orthodontist (H.I.) to eliminate interexaminer variability. Cephalometric analyses were performed with a cephalometric software program (Winceph 5.5, Rise, Sendai, Japan), on a personal computer. Soft tissue reference points and angles are shown in Figure 1. We obtained 7 angular and 2 linear measurements, and 1 ratio-related measurement for the soft tissue analysis (Table I). The mean and standard deviations (SD) for soft tissue measurements were determined for each sex (Table I). These values were found to be within 1 SD of current Japanese cephalometric dimensions.17 With these mean values, average Japanese profile silhouettes were constructed for men and women. Alcalde et al14 reported that the mean ⫾ SD for Japanese cephalometric norms for nasolabial angle, Ls to Sn-Pg’, and Li to Sn-Pg’ were 102.34° ⫾ 11.62°, 5.79° ⫾ 2.12°, and 5.03° ⫾ 2.49°, respectively.
For the orthodontist raters, the top 3 most-favored male profiles were 6, 5, and 4; the most-favored female profiles were 5, 4, and 6 (Fig 3). For the dental students, the 3 most-favored male profiles were 5, 4, and 6, and the 3 most-favored female profiles were 3, 4, and 5 (Fig 3). The orthodontists and the dental students both chose 13 as the least-favored profile for men and women. From the most-favored profiles rated by the orthodontists, the ranges of the following soft tissue measurements were determined: lip protrusion to Sn-Pg’ and the esthetic line, and Z-angle (Table II). The same ranges were recorded for the dental students in Table III. For men rated by both the orthodontists and the dental students, the most-favored lip protrusion values relative to Sn-Pg’ ranged from 3.4 to 5.4 mm for the upper lip and from 2.7 to 4.7 mm for the lower lip. The most-favored lip protrusion range relative to the esthetic line was from –5.5 to –3.5 mm for the upper lip and –2.0 to 0 mm for the lower lip. The range of most-favored Z-angle values was 72.0° to 75.0°. For women rated by the orthodontists, the ranges of the most-favored lip protrusion values relative to Sn-Pg’ were 3.5 to 5.5 mm for the upper lip and 3.4 to 5.4 mm for the lower lip. The most-favored lip protrusion range relative to the esthetic line was – 4.0 to –2.0 mm for the upper lip and –1.0 to 1.0 mm for the lower lip. The range of most-favored Z-angle values was 72.0° to 74.0°.
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Table I.
American Journal of Orthodontics and Dentofacial Orthopedics August 2005
Mean and SD of Japanese soft tissue measurements Men Variables
Facial form Angle of nasal prominence (°) Collumellar length angle (°) Nasal tip angle (°) Facial convexity (G=-Sn-Pg=) (°) Vertical height ratio (G=-Sn/Sn-Me=) Lip position Nasolabial angle (Cm-Sn-Ls) (°) Upper lip protrusion (Ls to Sn-Pg=) (mm) Lower lip protrusion (Li to Sn-Pg=) (mm) Inferior labial sulcus angle (°) Z-angle (chin/lip line to FH plane) (°)
Women
Mean
SD
Mean
SD
31.3 22.3 75.7 11.5 0.95
2.4 1.8 8.4 2.9 0.05
30.3 21.2 83.6 13.2 0.92
4.0 2.0 7.3 4.9 0.09
93.8 6.4 5.7 129.6 69.0
11.3 1.6 1.9 13.7 5.4
99.8 6.5 6.4 140.5 66.6
8.5 1.5 1.9 13.8 7.1
Fig 2. Series of 13 profiles rated by orthodontists and dental students for men (upper row) and women (lower row).
For women rated by dental students, the ranges of the most-favored lip protrusion values relative to Sn-Pg’ were 2.5 to 4.5 mm for the upper lip and 2.4 to 4.4 mm for the lower lip. The most-favored lip protrusion ranges relative to the esthetic line were – 4.5 to –2.5 mm for the upper lip and –1.5 to 0.5 mm for the lower lip. The range of most-favored Z-angle values was 73.0° to 75.0°.
DISCUSSION
The objectives of orthodontic treatment are to achieve facial balance, by stabilizing the dentition, and pleasing facial and dental esthetics.18 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 phi-
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Fig 3. Distribution of most-favored profiles. A, orthodontists rating men; B, orthodontists rating women; C, dental students rating men; D, dental students rating women. Table II. Range of preferred Japanese lip protrusion values by orthodontists
Table III.
Range of preferred Japanese lip protrusion values by dental students
Range Variables
Men
Lip position Upper lip protrusion (Ls to Sn-Pg=) (mm) 3.4 - 5.4 Lower lip protrusion (Li to Sn-Pg=) (mm) 2.7 - 4.7 Upper lip to E-line (Ls to E-line) (mm) –5.5 - –3.5 Lower lip to E-line (Li to E-line) (mm) –2.0 - 0 Z-angle (chin/lip line to FH plane) (°) 72.0 - 75.0
Women
3.5 - 5.5 3.4 - 5.4 –4.0 - –2.0 –1.0 - 1.0 72.0 - 74.0
losophers and artists, attempted to define beauty. However, it was difficult to determine the standards of beauty, because of tremendous variations among people in different racial groups.18 There are many studies on the norms of the well-balanced Japanese face,3-14 but most were performed between 1950 and 1970 .3-10 To date, only a few studies have attempted to quantify soft tissue lip positions of well-balanced Japanese subjects.8,10,11 Because the perception of beauty might have changed with time, it appears reasonable to reevaluate the perception of the well-balanced, pleasing Japanese face in the 21st century. Worldwide communications through the media, such as the Internet,
Range Variables
Men
Lip position Upper lip protrusion (Ls to Sn-Pg=) (mm) 3.4 - 5.4 Lower lip protrusion (Li to Sn-Pg=) (mm) 2.7 - 4.7 Upper lip to E-line (Ls to E-line) (mm) –5.5 - –3.5 Lower lip to E-line (Li to E-line) (mm) –2.0 - 0 Z-angle (chin/lip line to FH plane) (°) 72.0 - 75.0
Women
2.5 - 4.5 2.4 - 4.4 –4.5 - –2.5 –1.5 - 0.5 73.0 - 75.0
television, movies, and magazines, have expanded in recent years. People who are potential candidates for orthodontic treatment are likely to be profoundly influenced by these media. Our hypothesis is that the perception of beauty might have changed because of an increase in worldwide access to variations in pleasing facial profiles. The objective of this study was to determine, assess, and compare the range of values of well-balanced, facial profiles by Japanese orthodontists and dental students. The orthodontists rated the most-favored Japanese profiles as slightly more retruded than the average for both men and women. If the raters in this study chose
210 Ioi et al
the average profile as the well-balanced one, they should have selected 7; 6 was considered most favored for men and 5 for women. The tendency was to prefer a slightly more retruded lip position than the average lip position for women. The dental students regarded 5 as the best profile for men and 3 as the best for women. The dental students favored a slightly more retruded lip position for men and women than did the orthodontists. Therefore, it is important to consider the perceptions of young adults or nonorthodontists in determining wellbalanced facial profiles. The same tendency of Japanese to prefer a flatter profile was reported in previous articles.12,14 These authors described the Japanese as favoring a flatter profile, as did white people, even though their profiles were characterized by convex features.12 These results might imply that a perception regarding beauty has been established around each racial norm. The least-favored profile was consistently the most protrusive for both rater groups. This finding might suggest that orthodontic patients with protrusive lips seek straighter profiles through orthodontic treatment. For men, orthodontists and dental students preferred the same ranges of the favored lip protrusion relative to Ls to Sn-Pg’, Li to Sn-Pg’, Ls to E-line, Li to E-line, and Z-angle, respectively. For women, the dental students preferred a slightly more retruded lip position than the orthodontists, differing by 0.5 to 1.0 mm. A slightly more retruded lip position was favored by the dental students relative to Sn-Pg’ and the esthetic line. Similar findings were reported by Alcalde et al,14 who compared the differences in lip position between a normal Japanese group and a supernormal pleasant Japanese group. He stated that the lip protrusion relative to Sn-Pg’ for the pleasant Japanese norm was 4.6 mm at the upper lip and 3.1 mm at the lower lip, including men and women. Nezu et al19 reported that normal lower lip protrusion to the esthetic line was 2.0 mm in Japanese people and –2.0 mm in white people. These findings indicated that the flatter, white profile was favored for Japanese men and women. In some Western countries, a common perception is that more protrusive lips are more desirable in women than men.18 Although both men and women favored a more retruded lip position than the mean values for each sex, a similar tendency was preferred for women compared with men, when observed by Japanese raters. In this study, the mean values of Z-angle for the Japanese male and female subjects were 69.0° and 66.6°, respectively. Iwasawa et al20 reported that Z-angles for Japanese men and women were 69.7° and 71.8°, respectively. We found slightly larger Z-angle
American Journal of Orthodontics and Dentofacial Orthopedics August 2005
values in the most-favored profiles compared with these mean values. This result might also show that the Japanese prefer a straight profile over a convex one. Because the mean value of Z-angle for white people21 is 80.2°, there is still considerable difference between the Japanese-favored Z-angle and the white norm. This might be due to the more retruded chin and generally protruding mandibular incisors inherent in the Japanese population. In this study, we established a range of soft tissue lip-position values for the most-favored Japanese profile. We should not treat our patients to all look alike. Some patients might not want their facial features altered to those considered to be well balanced. Different racial groups have different perceptions of what is attractive.18 CONCLUSIONS
1. Both the orthodontists and the dental students tended to prefer a slightly more retruded lip position than the average silhouette. 2. In the estimation of both the orthodontists and the dental students for men, the ranges of the favored lip protrusion relative to Sn-Pg’ were 3.4 to 5.4 mm at the upper lip and 2.7 to 4.7 mm at the lower lip, respectively. In the estimation of the orthodontists for women, the ranges of the favored lip protrusion relative to Sn-Pg’ were 3.5 to 5.5 mm at the upper lip and 3.4 to 5.4 mm at the lower lip, respectively. A slightly more retruded position was favored by the dental students. 3. For men rated by both the orthodontists and the dental students, the range of most-favored Z-angle values was 72.0° to 75.0°. On the other hand, for women, the ranges of most-favored Z-angle values were 72.0° to 74.0° and 73.0° to 75.0° rated by the orthodontists and the dental students, respectively. Additional research, on the issue of the hard tissue analysis for most-favored profiles in young Japanese adults, appears to be warranted.1,21
REFERENCES 1. Iwasawa T, Moro T, Nakamura K. Considerations of the soft tissues of normal occlusal subjects with good face and Tweed triangle [in Japanese]. J Jpn Orthod 1974;33:99-104. 2. Sarver DM, Proffit WR, Ackerman JL. Diagnosis and treatment planning in orthodontics. In: Graber TM, Vanarsdall RL Jr, editors. Orthodontics, current principles and techniques. 3rd ed. Saint Louis: Mosby; 2000. 3. Yamauchi K. Studies on “beautiful face” of Japanese female adult: part 1, roentgenocephalometric analysis [in Japanese]. J Jpn Orthod 1959;18:18-20.
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4. Yamauchi K, Sakuda M. Relationship between dental arch and craniofacial components: Japanese male adults with normal occlusions [in Japanese]. J Jpn Orthod 1959;18:21-4. 5. Yamauchi K, Sakuda M. Studies on “acceptable face” of Japanese female adults: part 2, photostatic-cephalometric analysis [in Japanese]. J Jpn Orthod 1961;20:145-50. 6. Ito K, Suematsu H. Cephalometric study on the profile of Japanese young adult females with normal occlusion [in Japanese]. J Jpn Orthod 1967;26:35-41. 7. Yamauchi K, Ito K, Suematsu H, Ozeki S. Sex difference of Japanese adult profile with normal occlusion on cephalometric roentgenograms [in Japanese]. J Jpn Orthod 1967;26:155-60. 8. Shishikura K. The study on measurements of hard and soft tissue by cephalograms—particularly on normal and Class I occlusion among Japanese adults [in Japanese]. J Jpn Orthod 1969;28:26373. 9. Yogosawa F. The relationship between dentoskeletal framework and soft tissue profile [in Japanese]. J Jpn Orthod 1969;28:33-59. 10. Sebata M, Kikuchi M, Nogami K, Harasaki M, Ichimura K. Studies for establishing basis of construction of harmonious profile of Japanese [in Japanese]. J Jpn Orthod 1972;31:87-104. 11. Miyajima K, McNamara JA, Kimura T, Murata S, Iizuka T. Craniofacial structure of Japanese and European-American adults with normal occlusions and well-balanced faces. Am J Orthod Dentofacial Orthop 1996;110:431-8.
12. Ishii K, Yamaki M, Saito I, Kaloust S, Hanada K. WWW-based investigations of profile preferences among Caucasians and Japanese. Orthod Waves 1998;57:425-30. 13. Mantzikos T. Esthetic soft tissue profile preferences among the Japanese population. Am J Orthod Dentofacial Orthop 1998;114: 1-7. 14. 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. 15. Foster FJ. Profile preferences among diversified groups. Angle Orthod 1973;43:34-40. 16. Czarnecki ST, Nanda RS, Currier GF. Perceptions of a balanced facial profile. Am J Orthod Dentofacial Orthop 1993;104:180-7. 17. Izuka T, Ishikawa H. Normal standards for various cephalometric analysis in Japanese adults [in Japanese]. J Jpn Orthod 1957;16:4-12. 18. Burstone CJ, Marcotte MR. Problem solving in orthodontics. Carol Stream (Ill): Quintessence; 2000. 19. Nezu H, Nagata K, Yoshida Y, Kosaka H, Kikuchi M. Cephalometric comparison of clinical norms between the Japanese and Caucasians [in Japanese]. J Jpn Orthod 1982;41:450-65. 20. Iwasawa T, Moro T, Nakamura K. Tweed triangle and soft-tissue consideration of Japanese with normal occlusion and good facial profile. Am J Orthod 1977;72:119-27. 21. Merrifield LL. The profile line as an aid in critically evaluating facial esthetics. Am J Orthod 1966;52:804-22.
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Anteroposterior lip positions of the mostfavored Japanese facial profiles Hideki Ioi,aⴱ Shunsuke Nakata,b Akihiko Nakasima,c and Amy L. Countsd Fukuoka, Japan, and Oklahoma City, Okla Introduction: Soft tissue analysis is a basic tool in planning orthodontic treatment. However, the components of a well-balanced Japanese facial profile have not yet been established. The purpose of this study was to assess the most-favored or most well-balanced profile from a series of facial silhouettes with varying anteroposterior lip positions by a group of Japanese orthodontists and a group of young adult Japanese dental students. Methods: Average female and male profiles were constructed from the profiles of 30 Japanese men and women with normal occlusions. The lips in each average profile were protruded or retruded in 1-mm increments, and the 13 images were arranged with the average profile in the center. Forty two orthodontists and 42 dental students were asked to select the 3 most-favored, well-balanced profiles for each sex and rank them in order of preference. Results: Both the orthodontists and the students preferred a profile with slightly retruded lips. The dental students favored a more retruded lip position for women. The least-favored profile was the most protrusive. Conclusions: These findings suggest that Japanese orthodontists and young adults prefer a retruded profile, even though Japanese profiles have historically been characterized by more convex facial features. (Am J Orthod Dentofacial Orthop 2005;128:206-11)
T
reatment-planning goals for orthodontic treatment and orthognathic surgery are based on established normal values for each ethnic group. For example, the average anteroposterior lip position in Japanese adults is regarded as relatively more protrusive to that of white people.1 The perceptions of nonorthodontists should be considered in determining a well-balanced, pleasant profile, because the goals of orthodontic treatment are not only to achieve a functional occlusion, but also to create an esthetic profile.2 Soft tissue analyses of wellbalanced Japanese faces have been previously conducted3-14 from the 1950s to the 1970s.3-10 However, there are no studies of profiles evaluated by young adults who could become orthodontic patients. At the present time, young adults experience much exposure to mass media–ie, the Internet and worldwide communication and travel. The perception of a pleasa
Assistant professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. b Associate professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. c Professor, Department of Orthodontics, Faculty of Dentistry, Kyushu University, Fukuoka, Japan. d Associate professor, Department of Orthodontics, College of Dentistry, University of Oklahoma, Oklahoma City. Reprint requests to: Hideki Ioi, Department of Orthodontics, Faculty of Dentistry, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; e-mail, [email protected]. Submitted, December 2003; revised and accepted, April 2004. 0889-5406/$30.00 Copyright © 2005 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2004.04.030
206
ing facial profile might be changing because of these international influences. In light of these rapid developments, this study aimed to determine the perceptions of Japanese orthodontists and young adult Japanese dental students of well-balanced, pleasing profiles. Facial silhouettes were chosen for rating facial profiles, rather than facial photos, to avoid subjective considerations.15,16 The purpose of this study was to assess and determine the range of soft tissue anteroposterior lip position of the top 3 mostfavored, well-balanced profiles of each sex from a series of varying lip positions in facial silhouettes. MATERIAL AND METHODS
Average Japanese silhouettes were constructed from 30 cephalometric radiographs (15 men and 15 women) of adults aged 22 to 26 years. Inclusion criteria for this study were an ANB angle between 2° and 5°, a normal occlusion with minor or no crowding, all teeth present except third molars, no previous orthodontic treatment, and no prosthetic replacement of teeth. All lateral cephalometric radiographs were taken with the teeth in maximum intercuspation in a cephalostat oriented to the Frankfort horizontal plane. The radiographs were taken with a DR-15523HC (SSR-2B) cephalostat (Hitachi Medical Corporation, Tokyo, Japan) and exposed at 100 kV, 10 mA. All radiographs were traced by hand on matte acetate sheets and digitized on a personal computer
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To assess method error, 10 cases were randomly selected and traced at 3 separate times. One-way analysis of variance, used to test the equality of means for the cephalometric measurements, suggested that it was done consistently. Mean scores for the soft tissue measurements (P ⫽ .82) did not significantly differ among the 3 separate measurements. The method error can be considered negligible. Series of 13 profiles were developed for men and women (Fig 2). The average profile7 was in the center. The lips were protruded or retruded in 1-mm increments from the average profile, and the lip positions were changed parallel to the Frankfort horizontal plane. Profile 1 is the most retrusive, and 13 is the most protrusive. The profile raters were 42 Japanese orthodontists (20 men, aged 38.0 ⫾ 10.3 years; 22 women, aged 27.6 ⫾ 2.3 years), and 42 dental students (30 men, aged 24.6 ⫾ 1.9 years; 12 women, aged 25.1 ⫾ 2.7 years). They were asked to choose the top 3 most-favored profiles and rank them, with number 1 as the best. They were also asked to choose the least-favored profile. RESULTS
Fig 1. Soft tissue cephalometric reference points and analysis: 1, angle of nasal prominence; 2, collumellar length angle; 3, nasal tip angle; 4, nasolabial angle (Cm-Sn-Ls); 5, upper lip protrusion (Ls to Sn-Pg’); 6, lower lip protrusion (Li to Sn-Pg’); 7, inferior labial sulcus angle; 8, facial convexity (G’-Sn-Pg’); 9, Z-angle (chin/ lip line to FH plane).
by an orthodontist (H.I.) to eliminate interexaminer variability. Cephalometric analyses were performed with a cephalometric software program (Winceph 5.5, Rise, Sendai, Japan), on a personal computer. Soft tissue reference points and angles are shown in Figure 1. We obtained 7 angular and 2 linear measurements, and 1 ratio-related measurement for the soft tissue analysis (Table I). The mean and standard deviations (SD) for soft tissue measurements were determined for each sex (Table I). These values were found to be within 1 SD of current Japanese cephalometric dimensions.17 With these mean values, average Japanese profile silhouettes were constructed for men and women. Alcalde et al14 reported that the mean ⫾ SD for Japanese cephalometric norms for nasolabial angle, Ls to Sn-Pg’, and Li to Sn-Pg’ were 102.34° ⫾ 11.62°, 5.79° ⫾ 2.12°, and 5.03° ⫾ 2.49°, respectively.
For the orthodontist raters, the top 3 most-favored male profiles were 6, 5, and 4; the most-favored female profiles were 5, 4, and 6 (Fig 3). For the dental students, the 3 most-favored male profiles were 5, 4, and 6, and the 3 most-favored female profiles were 3, 4, and 5 (Fig 3). The orthodontists and the dental students both chose 13 as the least-favored profile for men and women. From the most-favored profiles rated by the orthodontists, the ranges of the following soft tissue measurements were determined: lip protrusion to Sn-Pg’ and the esthetic line, and Z-angle (Table II). The same ranges were recorded for the dental students in Table III. For men rated by both the orthodontists and the dental students, the most-favored lip protrusion values relative to Sn-Pg’ ranged from 3.4 to 5.4 mm for the upper lip and from 2.7 to 4.7 mm for the lower lip. The most-favored lip protrusion range relative to the esthetic line was from –5.5 to –3.5 mm for the upper lip and –2.0 to 0 mm for the lower lip. The range of most-favored Z-angle values was 72.0° to 75.0°. For women rated by the orthodontists, the ranges of the most-favored lip protrusion values relative to Sn-Pg’ were 3.5 to 5.5 mm for the upper lip and 3.4 to 5.4 mm for the lower lip. The most-favored lip protrusion range relative to the esthetic line was – 4.0 to –2.0 mm for the upper lip and –1.0 to 1.0 mm for the lower lip. The range of most-favored Z-angle values was 72.0° to 74.0°.
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Table I.
American Journal of Orthodontics and Dentofacial Orthopedics August 2005
Mean and SD of Japanese soft tissue measurements Men Variables
Facial form Angle of nasal prominence (°) Collumellar length angle (°) Nasal tip angle (°) Facial convexity (G=-Sn-Pg=) (°) Vertical height ratio (G=-Sn/Sn-Me=) Lip position Nasolabial angle (Cm-Sn-Ls) (°) Upper lip protrusion (Ls to Sn-Pg=) (mm) Lower lip protrusion (Li to Sn-Pg=) (mm) Inferior labial sulcus angle (°) Z-angle (chin/lip line to FH plane) (°)
Women
Mean
SD
Mean
SD
31.3 22.3 75.7 11.5 0.95
2.4 1.8 8.4 2.9 0.05
30.3 21.2 83.6 13.2 0.92
4.0 2.0 7.3 4.9 0.09
93.8 6.4 5.7 129.6 69.0
11.3 1.6 1.9 13.7 5.4
99.8 6.5 6.4 140.5 66.6
8.5 1.5 1.9 13.8 7.1
Fig 2. Series of 13 profiles rated by orthodontists and dental students for men (upper row) and women (lower row).
For women rated by dental students, the ranges of the most-favored lip protrusion values relative to Sn-Pg’ were 2.5 to 4.5 mm for the upper lip and 2.4 to 4.4 mm for the lower lip. The most-favored lip protrusion ranges relative to the esthetic line were – 4.5 to –2.5 mm for the upper lip and –1.5 to 0.5 mm for the lower lip. The range of most-favored Z-angle values was 73.0° to 75.0°.
DISCUSSION
The objectives of orthodontic treatment are to achieve facial balance, by stabilizing the dentition, and pleasing facial and dental esthetics.18 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 phi-
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Fig 3. Distribution of most-favored profiles. A, orthodontists rating men; B, orthodontists rating women; C, dental students rating men; D, dental students rating women. Table II. Range of preferred Japanese lip protrusion values by orthodontists
Table III.
Range of preferred Japanese lip protrusion values by dental students
Range Variables
Men
Lip position Upper lip protrusion (Ls to Sn-Pg=) (mm) 3.4 - 5.4 Lower lip protrusion (Li to Sn-Pg=) (mm) 2.7 - 4.7 Upper lip to E-line (Ls to E-line) (mm) –5.5 - –3.5 Lower lip to E-line (Li to E-line) (mm) –2.0 - 0 Z-angle (chin/lip line to FH plane) (°) 72.0 - 75.0
Women
3.5 - 5.5 3.4 - 5.4 –4.0 - –2.0 –1.0 - 1.0 72.0 - 74.0
losophers and artists, attempted to define beauty. However, it was difficult to determine the standards of beauty, because of tremendous variations among people in different racial groups.18 There are many studies on the norms of the well-balanced Japanese face,3-14 but most were performed between 1950 and 1970 .3-10 To date, only a few studies have attempted to quantify soft tissue lip positions of well-balanced Japanese subjects.8,10,11 Because the perception of beauty might have changed with time, it appears reasonable to reevaluate the perception of the well-balanced, pleasing Japanese face in the 21st century. Worldwide communications through the media, such as the Internet,
Range Variables
Men
Lip position Upper lip protrusion (Ls to Sn-Pg=) (mm) 3.4 - 5.4 Lower lip protrusion (Li to Sn-Pg=) (mm) 2.7 - 4.7 Upper lip to E-line (Ls to E-line) (mm) –5.5 - –3.5 Lower lip to E-line (Li to E-line) (mm) –2.0 - 0 Z-angle (chin/lip line to FH plane) (°) 72.0 - 75.0
Women
2.5 - 4.5 2.4 - 4.4 –4.5 - –2.5 –1.5 - 0.5 73.0 - 75.0
television, movies, and magazines, have expanded in recent years. People who are potential candidates for orthodontic treatment are likely to be profoundly influenced by these media. Our hypothesis is that the perception of beauty might have changed because of an increase in worldwide access to variations in pleasing facial profiles. The objective of this study was to determine, assess, and compare the range of values of well-balanced, facial profiles by Japanese orthodontists and dental students. The orthodontists rated the most-favored Japanese profiles as slightly more retruded than the average for both men and women. If the raters in this study chose
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the average profile as the well-balanced one, they should have selected 7; 6 was considered most favored for men and 5 for women. The tendency was to prefer a slightly more retruded lip position than the average lip position for women. The dental students regarded 5 as the best profile for men and 3 as the best for women. The dental students favored a slightly more retruded lip position for men and women than did the orthodontists. Therefore, it is important to consider the perceptions of young adults or nonorthodontists in determining wellbalanced facial profiles. The same tendency of Japanese to prefer a flatter profile was reported in previous articles.12,14 These authors described the Japanese as favoring a flatter profile, as did white people, even though their profiles were characterized by convex features.12 These results might imply that a perception regarding beauty has been established around each racial norm. The least-favored profile was consistently the most protrusive for both rater groups. This finding might suggest that orthodontic patients with protrusive lips seek straighter profiles through orthodontic treatment. For men, orthodontists and dental students preferred the same ranges of the favored lip protrusion relative to Ls to Sn-Pg’, Li to Sn-Pg’, Ls to E-line, Li to E-line, and Z-angle, respectively. For women, the dental students preferred a slightly more retruded lip position than the orthodontists, differing by 0.5 to 1.0 mm. A slightly more retruded lip position was favored by the dental students relative to Sn-Pg’ and the esthetic line. Similar findings were reported by Alcalde et al,14 who compared the differences in lip position between a normal Japanese group and a supernormal pleasant Japanese group. He stated that the lip protrusion relative to Sn-Pg’ for the pleasant Japanese norm was 4.6 mm at the upper lip and 3.1 mm at the lower lip, including men and women. Nezu et al19 reported that normal lower lip protrusion to the esthetic line was 2.0 mm in Japanese people and –2.0 mm in white people. These findings indicated that the flatter, white profile was favored for Japanese men and women. In some Western countries, a common perception is that more protrusive lips are more desirable in women than men.18 Although both men and women favored a more retruded lip position than the mean values for each sex, a similar tendency was preferred for women compared with men, when observed by Japanese raters. In this study, the mean values of Z-angle for the Japanese male and female subjects were 69.0° and 66.6°, respectively. Iwasawa et al20 reported that Z-angles for Japanese men and women were 69.7° and 71.8°, respectively. We found slightly larger Z-angle
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values in the most-favored profiles compared with these mean values. This result might also show that the Japanese prefer a straight profile over a convex one. Because the mean value of Z-angle for white people21 is 80.2°, there is still considerable difference between the Japanese-favored Z-angle and the white norm. This might be due to the more retruded chin and generally protruding mandibular incisors inherent in the Japanese population. In this study, we established a range of soft tissue lip-position values for the most-favored Japanese profile. We should not treat our patients to all look alike. Some patients might not want their facial features altered to those considered to be well balanced. Different racial groups have different perceptions of what is attractive.18 CONCLUSIONS
1. Both the orthodontists and the dental students tended to prefer a slightly more retruded lip position than the average silhouette. 2. In the estimation of both the orthodontists and the dental students for men, the ranges of the favored lip protrusion relative to Sn-Pg’ were 3.4 to 5.4 mm at the upper lip and 2.7 to 4.7 mm at the lower lip, respectively. In the estimation of the orthodontists for women, the ranges of the favored lip protrusion relative to Sn-Pg’ were 3.5 to 5.5 mm at the upper lip and 3.4 to 5.4 mm at the lower lip, respectively. A slightly more retruded position was favored by the dental students. 3. For men rated by both the orthodontists and the dental students, the range of most-favored Z-angle values was 72.0° to 75.0°. On the other hand, for women, the ranges of most-favored Z-angle values were 72.0° to 74.0° and 73.0° to 75.0° rated by the orthodontists and the dental students, respectively. Additional research, on the issue of the hard tissue analysis for most-favored profiles in young Japanese adults, appears to be warranted.1,21
REFERENCES 1. Iwasawa T, Moro T, Nakamura K. Considerations of the soft tissues of normal occlusal subjects with good face and Tweed triangle [in Japanese]. J Jpn Orthod 1974;33:99-104. 2. Sarver DM, Proffit WR, Ackerman JL. Diagnosis and treatment planning in orthodontics. In: Graber TM, Vanarsdall RL Jr, editors. Orthodontics, current principles and techniques. 3rd ed. Saint Louis: Mosby; 2000. 3. Yamauchi K. Studies on “beautiful face” of Japanese female adult: part 1, roentgenocephalometric analysis [in Japanese]. J Jpn Orthod 1959;18:18-20.
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4. Yamauchi K, Sakuda M. Relationship between dental arch and craniofacial components: Japanese male adults with normal occlusions [in Japanese]. J Jpn Orthod 1959;18:21-4. 5. Yamauchi K, Sakuda M. Studies on “acceptable face” of Japanese female adults: part 2, photostatic-cephalometric analysis [in Japanese]. J Jpn Orthod 1961;20:145-50. 6. Ito K, Suematsu H. Cephalometric study on the profile of Japanese young adult females with normal occlusion [in Japanese]. J Jpn Orthod 1967;26:35-41. 7. Yamauchi K, Ito K, Suematsu H, Ozeki S. Sex difference of Japanese adult profile with normal occlusion on cephalometric roentgenograms [in Japanese]. J Jpn Orthod 1967;26:155-60. 8. Shishikura K. The study on measurements of hard and soft tissue by cephalograms—particularly on normal and Class I occlusion among Japanese adults [in Japanese]. J Jpn Orthod 1969;28:26373. 9. Yogosawa F. The relationship between dentoskeletal framework and soft tissue profile [in Japanese]. J Jpn Orthod 1969;28:33-59. 10. Sebata M, Kikuchi M, Nogami K, Harasaki M, Ichimura K. Studies for establishing basis of construction of harmonious profile of Japanese [in Japanese]. J Jpn Orthod 1972;31:87-104. 11. Miyajima K, McNamara JA, Kimura T, Murata S, Iizuka T. Craniofacial structure of Japanese and European-American adults with normal occlusions and well-balanced faces. Am J Orthod Dentofacial Orthop 1996;110:431-8.
12. Ishii K, Yamaki M, Saito I, Kaloust S, Hanada K. WWW-based investigations of profile preferences among Caucasians and Japanese. Orthod Waves 1998;57:425-30. 13. Mantzikos T. Esthetic soft tissue profile preferences among the Japanese population. Am J Orthod Dentofacial Orthop 1998;114: 1-7. 14. 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. 15. Foster FJ. Profile preferences among diversified groups. Angle Orthod 1973;43:34-40. 16. Czarnecki ST, Nanda RS, Currier GF. Perceptions of a balanced facial profile. Am J Orthod Dentofacial Orthop 1993;104:180-7. 17. Izuka T, Ishikawa H. Normal standards for various cephalometric analysis in Japanese adults [in Japanese]. J Jpn Orthod 1957;16:4-12. 18. Burstone CJ, Marcotte MR. Problem solving in orthodontics. Carol Stream (Ill): Quintessence; 2000. 19. Nezu H, Nagata K, Yoshida Y, Kosaka H, Kikuchi M. Cephalometric comparison of clinical norms between the Japanese and Caucasians [in Japanese]. J Jpn Orthod 1982;41:450-65. 20. Iwasawa T, Moro T, Nakamura K. Tweed triangle and soft-tissue consideration of Japanese with normal occlusion and good facial profile. Am J Orthod 1977;72:119-27. 21. Merrifield LL. The profile line as an aid in critically evaluating facial esthetics. Am J Orthod 1966;52:804-22.
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