CLINICAL STUDY
Effect of Changes in Divine Proportion on Esthetic Perception of Smile in Frontal View Arezoo Jahanbin, DDS, MSc,* Maryam Poosti, DDS, MSc,Þ Soheil Salari, DDS, MSc,* Habibollah Esmaily, PhD,þ and Hoda Sagha, DDS* Objectives: In orthognathic surgery, the surgeon is capable of creating new dimensions to the patient’s face. Because a beautiful smile could be related to the divine proportion, the purpose of the current study was to evaluate the changes in the perception of smile after approximating some components of smile to the divine proportion orthodontically or surgically. Material and Methods: Ten 20- to 25-year-old women with pleasant smiles and no obvious malocclusions participated in this study. Five standard photographs were taken from each participant in a posed smile, and the most natural one was selected and scanned into black and white pictures. Ten anthropometric landmarks were detected on each image and 10 ratios including Labial inferioris (Li)/ right chelion (RCh)-right antegonion (RAgo), subnasale (Sn)-Li/left chelion (LCh)-left antegonion (LAgo), RCh-RAgo/labial superioris (Ls)-Li, LCh-LAgo/Ls-Li, Ch-Ch/Ls-Li,stomion (St)-Sn/St-Li, the maxillary central incisor width/maxillary centralincisor height, Ls-right cuspid (RCus)/RCh-RCus, Ls-left cuspid (LCus)/LCh-LCus, and LCus-RCus/Ch-Ch were measured on each picture. The numerators or denominators of the mentioned ratios were then changed in a way that mentioned the divine proportion (1/1.618) was approximated. All the 110 pictures were evaluated by 40 judges in 2 sessions using a visual analog scale. Intraclass correlation coefficient was also calculated (single measure, 0.644; F = 26.27; P G 0.001). The level of significance for this study was P = 0.05. The tests used to analyze the data were general linear model, the Friedman, and Wilcoxon tests. Results: This study showed that LCus-RCus/Ch-Ch, Ls-Lcus/LChLcus, and Ls-RCus/RCh-RCus (with mean scores of 64.2, 57.2, and 56.1, respectively) had the most positive effects on the esthetic perception of smile. However, RCh-RAgo/Ls-Li with a mean score of 29.1 and LCh-LAgo/Ls-Li with a mean score of 24.5 had the most negative effects. There were significant differences among the
From the *Department of Orthodontics, Dental School, Mashhad University of Medical Sciences, Mashhad; †Department of Orthodontics, Dental School, Islamic Azad Dental School, Tehran; and ‡Department of Community and Public Health, Mashhad University of Medical Sciences, Mashhad, Iran. Received February 15, 2013. Accepted for publication March 31, 2013. Address correspondence and reprint requests to Soheil Salari, MSC, Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Park Square, Mashhad, Iran; E-mail: [email protected] Supported by grant number 87638 from the Vice Chancellor for Research of Mashhad University of Medical Sciences. The authors report no conflicts of interest. Copyright * 2013 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0b013e31829a8607
1946
variables with each other except for A0 to J0 and A6 to J6 (F = 450.6; P = 0.001). Conclusions: Approximating the ratio RCus-LCus/Ch-Ch to the divine proportion may definitely help in achieving a more pleasant smile. On the next level, altering the ratios Ls-LCus/LCh-LCus and Ls-RCus/RCh-RCus could also play a role in making a beautiful smile. Key Words: Divine proportion, esthetic perception of smile, orthognathic surgery, facial frontal view (J Craniofac Surg 2013;24: 1946Y1949)
E
sthetics has been defined variously as the appreciation or the enjoyment of beauty.1 The divine proportion, or the golden section, is a mathematical relationship expressing universal harmony and, as such, an ideal measure governing the relationship of the elements of the human body.2 It is related to the Fibonacci series and is expressed as 1/1.618 or roughly 5/8.3 There have been many claims throughout history that the divine proportion was used in Greek art and architecture by the sculptor Phidias. This has led to its nickname as the ‘‘Phi’’ ratio.3 The term divine proportion was first used by the Italian mathematician Fra Luca Paciol4,5 in 1496. Leonardo da Vinci (1452j1519) defined proportion as the ratio between the respective parts and the whole.6 In 1946, Ghyka7 showed several divine proportions in the face of a tennis champion, Helen Wills. Lombardi8 was the first one to introduce the divine proportion to dentistry. In 1978, Levin9 discussed the golden rectangular in the anterior teeth. In 1982, the ‘‘golden proportion’’described by the ancient Greeks was popularized in orthodontics and surgery as the divine proportion by Ricketts.10 He claimed to find a large number of golden proportions after examining the lateral and frontal cephalograms that he considered to be ideal. Amoric11 also proved the existence of the divine proportion in many cephalometric measurements in different growth stages. In 2002, Baker and Woods12 evaluated the role of the divine proportion in the improvement of facial esthetics in orthognathic-orthodontic patients. They found no statistically significant differences in the ratios before and after the treatment. Furthermore, Marguardt13 developed a beauty mask on the basis of the divine proportion and showed that, regardless of race or age, if it conforms to the beauty mask, every face is deemed beautiful. If the ratio of the height to the length of the maxillary central incisor imitates the divine proportion, it will create a more beautiful and pleasing smile. Although some recent studies indicated that few golden proportions have a significant relationship with facial esthetics, some investigations showed that golden proportion is not a common factor in esthetic smiles.14Y16 As mentioned, a pleasant smile is an important, if not the most important, factor in creating an attractive face and this could be a goal in orthodontic and surgical treatments. In orthognathic surgery, the surgeon is capable of creating new dimensions to the patient’s face.
The Journal of Craniofacial Surgery
& Volume 24, Number 6, November 2013
The Journal of Craniofacial Surgery
& Volume 24, Number 6, November 2013
Changes in the Perception of Smile
The purpose of the current study was to evaluate the changes in the perception of smile after changing some components of facial dimensions orthodontically or surgically and approximate them to the divine proportion.
MATERIALS AND METHODS In this cross-sectional study, 10 women with pleasant smiles between the ages of 20 and 25 years were invited. The participants had no experience in undergoing an orthodontic treatment, cosmetic surgeries on the face, or extraction of teeth, except for third molars. The involvement of the participants in this study was approved by the University of Mashhad ethics committee. The aim of this study was explained clearly, and informed consent was obtained from each participant. The participants had no obvious malocclusion, facial asymmetry, or any problem in the anteroposterior and vertical facial proportions and lip-tooth relationship at rest and on smile. To take photographs in the natural head position, the participants were asked to stand up and look straight into their eyes’ image in the mirror located on the wall in front of them at the level of their pupils. Then, they were asked to ‘‘pose’’ a smile.17Y20 The photographs were taken using a digital camera (Panasonic Z30; Osaka, Japan) with Lumix lens. The distance between the camera and the participants was 465 mm. All photographs were then converted to black and white, using the Adobe Photoshop program (CS3 version 10.0; Pantone, Inc, Los Angeles, CA). Elimination of esthetic interferers such as skin and lip color, which, therefore, attracts the judges’ attention to the most critical area in this study (smile), is considered to be the advantage of black-and-white pictures in the evaluation of the photographs. Afterward, the following points were defined on all photographs (Fig. 1): - labial superioris (Ls): the middle point on the vermilion line of the upper lip - labial inferioris (Li): the middle point on the vermilion line of the lower lip - subnasale (Sn): a point located at the junction between the lower border of the nose and the beginning of the upper lip at the midsagittal plane - stomion (St): the median point of the oral embrasure - right chelion (RCh): a point located on the right commissure - left chelion (LCh): a point located on the left commissure - right antegonion (RAgo): a point located on the anterior limit of the right antegonial notch - left antegonion (LAgo): a point located on the anterior limit of the left antegonial notch
FIGURE 1. The points that were defined on the original photographs.
* 2013 Mutaz B. Habal, MD
FIGURE 2. After changing the Sn-Li/RCh-RAgo to the divine proportion.
- right cuspid (RCus): a point located on the most lateral surface of the right maxillary canine - left cuspid (LCus): a point located on the most lateral surface of the left maxillary canine Then, the following distances were measured: Sn-Li, RChRAgo, LCh-LAgo, Ls-Li, LCh-RCh St-Sn, St-Li, Ls-RCus, RChRCus, LCh-LCus, Ls-LCus, LCus-RCus, the maxillary central incisor height, and the maxillary central incisor width. The numerators or denominators of the following ratios were then changed in a way that divine proportion (1.618) was achieved: 1) Sn-Li/RCh-RAgo, 2) Sn-Li/LCh-LAgo, 3) RCh-RAgo/Ls-Li, 4) LCh-LAgo/Ls-Li, 5) Ch-Ch/Ls-Li, 6) St-Sn/St-Li, 7) Maxillary central incisor width/maxillary central incisor height, 8) Rs-RCus/RCh-RCus, 9) Ls-LCus/LCh-LCus, and 10) LCus-RCus/Ch-ch (Fig. 2) In making the new ratios, it was possible to change both the numerator and denominator of the fractions, however the one that was possible to be achieved by orthodontic or surgical treatments has been modified. The line that its length was changed (variable) was modified to the new length using Photoshop. The result was 10 new photographs for each of the original ones. We had 10 original photographs and 100 new ones. The original ones were named as A0, B0I J0 and the new ones were named as A1 to A10, B1 to B10I J1 to J10. The prepared photographs were displayed for 40 judges with different sexes, age, and educational background. The judge panel consisted of 8 orthodontists (4 males and 4 females), 16 junior dental students (8 males and 8 females), and 16 laypersons (8 males and 8 females), with ages ranging from 45 to 55 years. The photographs were then inserted into a PowerPoint slide show and were displayed for 10 seconds for the judges. A 100-mm visual analog scale score sheet was created to record the judges’ esthetic scores for each photograph on a scale of 0 (least attractive) to 100 (most attractive). To assess intraexaminer reliability, the judges were asked to evaluate the entire samples once again approximately 5 weeks after the first assessment with the same method. The photographs were randomly presented to the judges and not in a fixed order. In this study, intraclass correlation coefficient was also calculated (single measure, 0.644; F = 26.27; P G 0.001).
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Afterward, the mean scores given to the photographs by the judges in 2 intervals were calculated and the smiles were scaled on the basis of the following: excellent (80Y100), very good (60Y80), good (40Y60), moderate (20Y40), and poor (0Y20). Statistical analysis consisted of general linear model, the Friedman, and Wilcoxon tests (Statistical Package for the Social Sciences version 11.5; SPSS, Chicago, IL). The level of significance was set at P G 0.05.
RESULTS Table 1 shows the mean (SD) of the visual analog scale scores for all photographs. According to Table 1, LCus-RCus/Ch-Ch, LsLcus/LCh-Lcus, and Ls-RCus/RCh-RCus (with mean scores of 64.2, 57.2, and 56.1, respectively) had the most positive effects on the esthetic perception of smile; however, RCh-RAgo/Ls-Li with a mean score of 29.1 and LCh-LAgo/Ls-Li with a mean score of 24.5 had the most negative effects. According to the general linear model, there were significant differences among the variables with each other except for A0 to J0 and A6 to J6 (F = 450.6; P = 0.001). Table 2 shows the distribution of the sample groups based on their esthetic score. According to the Friedman test, all groups had significant differences with each other (W2 = 170.1; P G 0.001), except A0 to J0 with A6 to J6, A2 to J2 with A1 to J1, A5 to J5 with A1 to J1, A5 to J5 with A2 to J2, A8 to J8 with A7 to J7, A9 to J9 with A7 to J7, and A9 to J9 with A8 to J8. To compare variables with A0, we used the Wilcoxon test with the Bonferroni correction, which showed significant differences between all variables (P G 0.001) except A0 to J0 to A6 to J6 (P = 0.057).
DISCUSSION The number of studies aimed at facial proportions in creating an attractive smile is rare, and most of these usually focus on dental relationships, especially the maxillary central incisors. Among those are the studies of Levin9 and Cesario and Latta,16 which confirmed the existence of the divine proportion in the face. Jahanbin et al21 found that the perception of esthetics is influenced by the divine proportion in the facial profile of young females. In 1989, Haralabakis et al22 evaluated the facial proportions in females in 3 conditions: smile, rest, and serious mode. They concluded that the divine proportion is more common in rest and serious modes than in smile. In 2011, Scolozzi et al23 reported that facial divine proportion can be closely approximated and predicted only by a specific cephalometric analysis in the lower facial third and that parameters such as age, sex, type of dentofacial deformities, type of surgery, and
TABLE 1. Mean (SD) of the Visual Analog Scale Scores for All Samples Variable
Mean (SD)
A0 to J0 A1 to J1 A2 to J2 A3 to J3 A4 to J4 A5 to J5 A6 to J6 A7 to J7 A8 to J8 A9 to J9 A10 to J10
49.0 (2.3) 43.6 (2.4) 44.1 (1.9) 29.1 (2.3) 24.5 (2.3) 42.3 (3.1) 50.4 (2.9) 55.9 (1.9) 56.1 (2.3) 57.2 (2.3) 64.2 (3.4)
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& Volume 24, Number 6, November 2013
TABLE 2. Distribution of Sample Groups Based on Esthetic Score VAS Groups
Poor, n (%)
Moderate, n (%)
A0 to J0 A1 to J1 A2 to J2 A3 to J3 A4 to J4 A5 to J5 A6 to J6 A7 to J7 A8 to J8 A9 to J9 A10 to J10
0 (0) 0 (0) 0 (0) 0 (0) 1 (5) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
0 (0) 2 (10) 0 (0) 20 (100) 19 (95) 4 (20) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
Good, n (%)
Very Good, n (%)
Excellent, n (%)
20 (100) 18 (80) 20 (100) 0 (0) 0 (0) 16 (80) 20 (100) 19 (95) 0 (0) 0 (0) 0 (0)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1 (5) 18 (90) 18 (90) 2 (10)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 2 (10) 2 (10) 18 (90)
VAS indicates visual analogue scale.
so on could potentially and significantly influence the final results toward the divine proportion. The only study that has evaluated one of the facial ratios of the current research was the work of Levin.9 He investigated the relationship between the maxillary central incisor’s heights to the width of the 2 maxillary incisors and found the divine proportion in this ratio. Because one important goal of orthodontic and surgical treatments could be a beautiful smile, in this study, we investigated the proportions and ratios involved in creating such a smile. The current study showed that the golden proportion can be used in making pleasant smiles. According to the result of this study, none of the evaluated photographs were classified as ‘‘excellent.’’ Possibilities could be that 4 of the judges were dentists and that they might have scored more astringently on the basis of their academic knowledge of smile esthetics. Furthermore, perhaps the judges needed more esthetic aspects to classify the photographs above the ‘‘good’’ level. Although altering the photographs to black and white could eliminate the interferer factors such as complexion, makeups, and so on, in such a low-contrast environment, it is also capable of reducing the esthetic perception in the judges. We found that changing LCus-RCus/Ch-Ch to the divine proportion had the highest impact on the perception of smile esthetics in the judges’ standpoints. Widths of the maxillary anterior teeth that have been already investigated by Levin9 and Mahshid et al15 were considered to make a ‘‘good’’ smile in our study. Evaluating the judges’ scorings, we can conclude that LCusRCus/Ch-Ch, Ls-LCus/LCh-LCus, and Ls-RCus/RCh-RCus had more significant impact on the smile esthetics with mean scores of 64.2, 57.2, and 56.1, respectively. Although it may not be straightforward, positioning the buccal corridors in orthodontic or surgical treatments in such a way that the distance between the most lateral surfaces of the maxillary canines to the commissural width is more close to the divine proportion can help in creating more attractive and pleasant smiles.
CONCLUSIONS Many subjective and objective factors can influence the conception of a beautiful and pleasant smile. Approximating the ratio RCus-LCus/Ch-Ch to the divine proportion may definitely help in achieving a more pleasant smile. On the next level, altering the ratios Ls-LCus/LCh-LCus and Ls-RCus/RCh-RCus could play such a role in making a beautiful smile. * 2013 Mutaz B. Habal, MD
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& Volume 24, Number 6, November 2013
REFERENCES 1. Valentine CW. The experimental psychology of beauty. London: Methuen and Co Ltd, 1962:93Y96 2. Wood TJ. Aesthetics and Orthodontics. Dent Pract Dent Rec 1969;19:247Y260 3. Herz-Fischler R. A mathematical history of division in extreme and mean ratio. Waterloo, Ontario: Wilfred Laurier, 1987:164Y170 4. Taylor RE. No royal road. Chapel Hill: North Carolina University Press, 1942:251Y287 5. Stanley M. Fra luca de pacioli of Borogo S. Sepoicro. New York: Kraus Co, 1969:92 6. Pedretti C. Leonardo da Vinci: notebook of a genius. Milan: Powerhouse Publishing, 2001:150 7. Ghyka M. The geometry of art and life. New York: Steed & Ward, 1946:102Y107 8. Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosthet Dent 1973;29:358Y382 9. Levin EI. Dental esthetics and the golden proportion. J Prosthet Dent 1978;40:244Y252 10. Ricketts RM. The biologic significance of the divine proportion and Fibonacci series. Am J Orthod 1982;81:351Y370 11. Amoric M. The golden number: application to craniofacial evaluation. Funct Orthod 1995;12:18Y21, 24Y25 12. Baker BW, Woods MG. The role of the divine proportion in the esthetic improvement of patient urdergoing combined orthodontic/orthognathic surgical treatment. Int J Adult Orthod Orthognath Surg 2001;16: 108Y120 13. Marguardt SR. The Golden Decagon and human facial beauty. J Clin Orthod 2002;36:339Y347
* 2013 Mutaz B. Habal, MD
Changes in the Perception of Smile
14. Kiekens RM, Kuijpers-Jagtman AM, van ’t Hof MA, et al. Putative golden proportions as predictors of facial esthetics in adolescents. Am J Orthod Dentofacial Orthop 2008;134:480Y483 15. Mahshid M, Khoshvaghti A, Varshosaz M, et al. Evaluation of ‘‘golden proportion’’ in individuals with an esthetic smile. J Esthet Restor Dent 2004;16:185Y192 16. Cesario VA Jr, Latta GH Jr. Relationship between the mesiodistal width of the maxillary central incisor and interpupillary distance. J Prosthet Dent 1984;52:641Y643 17. Hulsey CM. An esthetic evaluation of lip-teeth relationships present in the smile. Am J Orthod 1970;57:132Y144 18. Rigsbee OH 3rd, Sperry TP, BeGole EA. The influence of facial animation on smile characteristics. Int J Adult Orthodon Orthognath Surg 1988;3:233Y239 19. Ackerman MB, Ackerman JL. Smile analysis and design in the digital era. J Clin Orthod 2002;36:221Y236 20. Tjan AH, Miller GD, The JG. Some esthetic factors in a smile. J Prosthet Dent 1984;51:24Y28 21. Jahanbin A, Basafa M, Alizadeh Y. Evaluation of the divine proportion in the facial profile of young females. Indian J Dent Res 2008;19: 292Y296 22. Haralabakis NB, Lagoudakis M, Spanoudakis E. A study of esthetic harmony and balance of the facial soft tissue [in Greek]. Orthod Epitheorese 1989;1:175Y189 23. Scolozzi P, Momjian A, Courvoisier D. Dentofacial deformities treated according to a dentoskeletal analysis based on the divine proportion: are the resulting faces de facto ‘‘divinely’’ proportioned? J Craniofac Surg 2011;22:147Y150
1949
Effect of Changes in Divine Proportion on Esthetic Perception of Smile in Frontal View Arezoo Jahanbin, DDS, MSc,* Maryam Poosti, DDS, MSc,Þ Soheil Salari, DDS, MSc,* Habibollah Esmaily, PhD,þ and Hoda Sagha, DDS* Objectives: In orthognathic surgery, the surgeon is capable of creating new dimensions to the patient’s face. Because a beautiful smile could be related to the divine proportion, the purpose of the current study was to evaluate the changes in the perception of smile after approximating some components of smile to the divine proportion orthodontically or surgically. Material and Methods: Ten 20- to 25-year-old women with pleasant smiles and no obvious malocclusions participated in this study. Five standard photographs were taken from each participant in a posed smile, and the most natural one was selected and scanned into black and white pictures. Ten anthropometric landmarks were detected on each image and 10 ratios including Labial inferioris (Li)/ right chelion (RCh)-right antegonion (RAgo), subnasale (Sn)-Li/left chelion (LCh)-left antegonion (LAgo), RCh-RAgo/labial superioris (Ls)-Li, LCh-LAgo/Ls-Li, Ch-Ch/Ls-Li,stomion (St)-Sn/St-Li, the maxillary central incisor width/maxillary centralincisor height, Ls-right cuspid (RCus)/RCh-RCus, Ls-left cuspid (LCus)/LCh-LCus, and LCus-RCus/Ch-Ch were measured on each picture. The numerators or denominators of the mentioned ratios were then changed in a way that mentioned the divine proportion (1/1.618) was approximated. All the 110 pictures were evaluated by 40 judges in 2 sessions using a visual analog scale. Intraclass correlation coefficient was also calculated (single measure, 0.644; F = 26.27; P G 0.001). The level of significance for this study was P = 0.05. The tests used to analyze the data were general linear model, the Friedman, and Wilcoxon tests. Results: This study showed that LCus-RCus/Ch-Ch, Ls-Lcus/LChLcus, and Ls-RCus/RCh-RCus (with mean scores of 64.2, 57.2, and 56.1, respectively) had the most positive effects on the esthetic perception of smile. However, RCh-RAgo/Ls-Li with a mean score of 29.1 and LCh-LAgo/Ls-Li with a mean score of 24.5 had the most negative effects. There were significant differences among the
From the *Department of Orthodontics, Dental School, Mashhad University of Medical Sciences, Mashhad; †Department of Orthodontics, Dental School, Islamic Azad Dental School, Tehran; and ‡Department of Community and Public Health, Mashhad University of Medical Sciences, Mashhad, Iran. Received February 15, 2013. Accepted for publication March 31, 2013. Address correspondence and reprint requests to Soheil Salari, MSC, Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Park Square, Mashhad, Iran; E-mail: [email protected] Supported by grant number 87638 from the Vice Chancellor for Research of Mashhad University of Medical Sciences. The authors report no conflicts of interest. Copyright * 2013 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0b013e31829a8607
1946
variables with each other except for A0 to J0 and A6 to J6 (F = 450.6; P = 0.001). Conclusions: Approximating the ratio RCus-LCus/Ch-Ch to the divine proportion may definitely help in achieving a more pleasant smile. On the next level, altering the ratios Ls-LCus/LCh-LCus and Ls-RCus/RCh-RCus could also play a role in making a beautiful smile. Key Words: Divine proportion, esthetic perception of smile, orthognathic surgery, facial frontal view (J Craniofac Surg 2013;24: 1946Y1949)
E
sthetics has been defined variously as the appreciation or the enjoyment of beauty.1 The divine proportion, or the golden section, is a mathematical relationship expressing universal harmony and, as such, an ideal measure governing the relationship of the elements of the human body.2 It is related to the Fibonacci series and is expressed as 1/1.618 or roughly 5/8.3 There have been many claims throughout history that the divine proportion was used in Greek art and architecture by the sculptor Phidias. This has led to its nickname as the ‘‘Phi’’ ratio.3 The term divine proportion was first used by the Italian mathematician Fra Luca Paciol4,5 in 1496. Leonardo da Vinci (1452j1519) defined proportion as the ratio between the respective parts and the whole.6 In 1946, Ghyka7 showed several divine proportions in the face of a tennis champion, Helen Wills. Lombardi8 was the first one to introduce the divine proportion to dentistry. In 1978, Levin9 discussed the golden rectangular in the anterior teeth. In 1982, the ‘‘golden proportion’’described by the ancient Greeks was popularized in orthodontics and surgery as the divine proportion by Ricketts.10 He claimed to find a large number of golden proportions after examining the lateral and frontal cephalograms that he considered to be ideal. Amoric11 also proved the existence of the divine proportion in many cephalometric measurements in different growth stages. In 2002, Baker and Woods12 evaluated the role of the divine proportion in the improvement of facial esthetics in orthognathic-orthodontic patients. They found no statistically significant differences in the ratios before and after the treatment. Furthermore, Marguardt13 developed a beauty mask on the basis of the divine proportion and showed that, regardless of race or age, if it conforms to the beauty mask, every face is deemed beautiful. If the ratio of the height to the length of the maxillary central incisor imitates the divine proportion, it will create a more beautiful and pleasing smile. Although some recent studies indicated that few golden proportions have a significant relationship with facial esthetics, some investigations showed that golden proportion is not a common factor in esthetic smiles.14Y16 As mentioned, a pleasant smile is an important, if not the most important, factor in creating an attractive face and this could be a goal in orthodontic and surgical treatments. In orthognathic surgery, the surgeon is capable of creating new dimensions to the patient’s face.
The Journal of Craniofacial Surgery
& Volume 24, Number 6, November 2013
The Journal of Craniofacial Surgery
& Volume 24, Number 6, November 2013
Changes in the Perception of Smile
The purpose of the current study was to evaluate the changes in the perception of smile after changing some components of facial dimensions orthodontically or surgically and approximate them to the divine proportion.
MATERIALS AND METHODS In this cross-sectional study, 10 women with pleasant smiles between the ages of 20 and 25 years were invited. The participants had no experience in undergoing an orthodontic treatment, cosmetic surgeries on the face, or extraction of teeth, except for third molars. The involvement of the participants in this study was approved by the University of Mashhad ethics committee. The aim of this study was explained clearly, and informed consent was obtained from each participant. The participants had no obvious malocclusion, facial asymmetry, or any problem in the anteroposterior and vertical facial proportions and lip-tooth relationship at rest and on smile. To take photographs in the natural head position, the participants were asked to stand up and look straight into their eyes’ image in the mirror located on the wall in front of them at the level of their pupils. Then, they were asked to ‘‘pose’’ a smile.17Y20 The photographs were taken using a digital camera (Panasonic Z30; Osaka, Japan) with Lumix lens. The distance between the camera and the participants was 465 mm. All photographs were then converted to black and white, using the Adobe Photoshop program (CS3 version 10.0; Pantone, Inc, Los Angeles, CA). Elimination of esthetic interferers such as skin and lip color, which, therefore, attracts the judges’ attention to the most critical area in this study (smile), is considered to be the advantage of black-and-white pictures in the evaluation of the photographs. Afterward, the following points were defined on all photographs (Fig. 1): - labial superioris (Ls): the middle point on the vermilion line of the upper lip - labial inferioris (Li): the middle point on the vermilion line of the lower lip - subnasale (Sn): a point located at the junction between the lower border of the nose and the beginning of the upper lip at the midsagittal plane - stomion (St): the median point of the oral embrasure - right chelion (RCh): a point located on the right commissure - left chelion (LCh): a point located on the left commissure - right antegonion (RAgo): a point located on the anterior limit of the right antegonial notch - left antegonion (LAgo): a point located on the anterior limit of the left antegonial notch
FIGURE 1. The points that were defined on the original photographs.
* 2013 Mutaz B. Habal, MD
FIGURE 2. After changing the Sn-Li/RCh-RAgo to the divine proportion.
- right cuspid (RCus): a point located on the most lateral surface of the right maxillary canine - left cuspid (LCus): a point located on the most lateral surface of the left maxillary canine Then, the following distances were measured: Sn-Li, RChRAgo, LCh-LAgo, Ls-Li, LCh-RCh St-Sn, St-Li, Ls-RCus, RChRCus, LCh-LCus, Ls-LCus, LCus-RCus, the maxillary central incisor height, and the maxillary central incisor width. The numerators or denominators of the following ratios were then changed in a way that divine proportion (1.618) was achieved: 1) Sn-Li/RCh-RAgo, 2) Sn-Li/LCh-LAgo, 3) RCh-RAgo/Ls-Li, 4) LCh-LAgo/Ls-Li, 5) Ch-Ch/Ls-Li, 6) St-Sn/St-Li, 7) Maxillary central incisor width/maxillary central incisor height, 8) Rs-RCus/RCh-RCus, 9) Ls-LCus/LCh-LCus, and 10) LCus-RCus/Ch-ch (Fig. 2) In making the new ratios, it was possible to change both the numerator and denominator of the fractions, however the one that was possible to be achieved by orthodontic or surgical treatments has been modified. The line that its length was changed (variable) was modified to the new length using Photoshop. The result was 10 new photographs for each of the original ones. We had 10 original photographs and 100 new ones. The original ones were named as A0, B0I J0 and the new ones were named as A1 to A10, B1 to B10I J1 to J10. The prepared photographs were displayed for 40 judges with different sexes, age, and educational background. The judge panel consisted of 8 orthodontists (4 males and 4 females), 16 junior dental students (8 males and 8 females), and 16 laypersons (8 males and 8 females), with ages ranging from 45 to 55 years. The photographs were then inserted into a PowerPoint slide show and were displayed for 10 seconds for the judges. A 100-mm visual analog scale score sheet was created to record the judges’ esthetic scores for each photograph on a scale of 0 (least attractive) to 100 (most attractive). To assess intraexaminer reliability, the judges were asked to evaluate the entire samples once again approximately 5 weeks after the first assessment with the same method. The photographs were randomly presented to the judges and not in a fixed order. In this study, intraclass correlation coefficient was also calculated (single measure, 0.644; F = 26.27; P G 0.001).
1947
The Journal of Craniofacial Surgery
Jahanbin et al
Afterward, the mean scores given to the photographs by the judges in 2 intervals were calculated and the smiles were scaled on the basis of the following: excellent (80Y100), very good (60Y80), good (40Y60), moderate (20Y40), and poor (0Y20). Statistical analysis consisted of general linear model, the Friedman, and Wilcoxon tests (Statistical Package for the Social Sciences version 11.5; SPSS, Chicago, IL). The level of significance was set at P G 0.05.
RESULTS Table 1 shows the mean (SD) of the visual analog scale scores for all photographs. According to Table 1, LCus-RCus/Ch-Ch, LsLcus/LCh-Lcus, and Ls-RCus/RCh-RCus (with mean scores of 64.2, 57.2, and 56.1, respectively) had the most positive effects on the esthetic perception of smile; however, RCh-RAgo/Ls-Li with a mean score of 29.1 and LCh-LAgo/Ls-Li with a mean score of 24.5 had the most negative effects. According to the general linear model, there were significant differences among the variables with each other except for A0 to J0 and A6 to J6 (F = 450.6; P = 0.001). Table 2 shows the distribution of the sample groups based on their esthetic score. According to the Friedman test, all groups had significant differences with each other (W2 = 170.1; P G 0.001), except A0 to J0 with A6 to J6, A2 to J2 with A1 to J1, A5 to J5 with A1 to J1, A5 to J5 with A2 to J2, A8 to J8 with A7 to J7, A9 to J9 with A7 to J7, and A9 to J9 with A8 to J8. To compare variables with A0, we used the Wilcoxon test with the Bonferroni correction, which showed significant differences between all variables (P G 0.001) except A0 to J0 to A6 to J6 (P = 0.057).
DISCUSSION The number of studies aimed at facial proportions in creating an attractive smile is rare, and most of these usually focus on dental relationships, especially the maxillary central incisors. Among those are the studies of Levin9 and Cesario and Latta,16 which confirmed the existence of the divine proportion in the face. Jahanbin et al21 found that the perception of esthetics is influenced by the divine proportion in the facial profile of young females. In 1989, Haralabakis et al22 evaluated the facial proportions in females in 3 conditions: smile, rest, and serious mode. They concluded that the divine proportion is more common in rest and serious modes than in smile. In 2011, Scolozzi et al23 reported that facial divine proportion can be closely approximated and predicted only by a specific cephalometric analysis in the lower facial third and that parameters such as age, sex, type of dentofacial deformities, type of surgery, and
TABLE 1. Mean (SD) of the Visual Analog Scale Scores for All Samples Variable
Mean (SD)
A0 to J0 A1 to J1 A2 to J2 A3 to J3 A4 to J4 A5 to J5 A6 to J6 A7 to J7 A8 to J8 A9 to J9 A10 to J10
49.0 (2.3) 43.6 (2.4) 44.1 (1.9) 29.1 (2.3) 24.5 (2.3) 42.3 (3.1) 50.4 (2.9) 55.9 (1.9) 56.1 (2.3) 57.2 (2.3) 64.2 (3.4)
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TABLE 2. Distribution of Sample Groups Based on Esthetic Score VAS Groups
Poor, n (%)
Moderate, n (%)
A0 to J0 A1 to J1 A2 to J2 A3 to J3 A4 to J4 A5 to J5 A6 to J6 A7 to J7 A8 to J8 A9 to J9 A10 to J10
0 (0) 0 (0) 0 (0) 0 (0) 1 (5) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
0 (0) 2 (10) 0 (0) 20 (100) 19 (95) 4 (20) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
Good, n (%)
Very Good, n (%)
Excellent, n (%)
20 (100) 18 (80) 20 (100) 0 (0) 0 (0) 16 (80) 20 (100) 19 (95) 0 (0) 0 (0) 0 (0)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1 (5) 18 (90) 18 (90) 2 (10)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 2 (10) 2 (10) 18 (90)
VAS indicates visual analogue scale.
so on could potentially and significantly influence the final results toward the divine proportion. The only study that has evaluated one of the facial ratios of the current research was the work of Levin.9 He investigated the relationship between the maxillary central incisor’s heights to the width of the 2 maxillary incisors and found the divine proportion in this ratio. Because one important goal of orthodontic and surgical treatments could be a beautiful smile, in this study, we investigated the proportions and ratios involved in creating such a smile. The current study showed that the golden proportion can be used in making pleasant smiles. According to the result of this study, none of the evaluated photographs were classified as ‘‘excellent.’’ Possibilities could be that 4 of the judges were dentists and that they might have scored more astringently on the basis of their academic knowledge of smile esthetics. Furthermore, perhaps the judges needed more esthetic aspects to classify the photographs above the ‘‘good’’ level. Although altering the photographs to black and white could eliminate the interferer factors such as complexion, makeups, and so on, in such a low-contrast environment, it is also capable of reducing the esthetic perception in the judges. We found that changing LCus-RCus/Ch-Ch to the divine proportion had the highest impact on the perception of smile esthetics in the judges’ standpoints. Widths of the maxillary anterior teeth that have been already investigated by Levin9 and Mahshid et al15 were considered to make a ‘‘good’’ smile in our study. Evaluating the judges’ scorings, we can conclude that LCusRCus/Ch-Ch, Ls-LCus/LCh-LCus, and Ls-RCus/RCh-RCus had more significant impact on the smile esthetics with mean scores of 64.2, 57.2, and 56.1, respectively. Although it may not be straightforward, positioning the buccal corridors in orthodontic or surgical treatments in such a way that the distance between the most lateral surfaces of the maxillary canines to the commissural width is more close to the divine proportion can help in creating more attractive and pleasant smiles.
CONCLUSIONS Many subjective and objective factors can influence the conception of a beautiful and pleasant smile. Approximating the ratio RCus-LCus/Ch-Ch to the divine proportion may definitely help in achieving a more pleasant smile. On the next level, altering the ratios Ls-LCus/LCh-LCus and Ls-RCus/RCh-RCus could play such a role in making a beautiful smile. * 2013 Mutaz B. Habal, MD
The Journal of Craniofacial Surgery
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* 2013 Mutaz B. Habal, MD
Changes in the Perception of Smile
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