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 pro- portion 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 superi- oris (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 numer- ators or denominators of the mentioned ratios were then changed in a way that mentioned the divine proportion (1/1.618) was approxi- mated. 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/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. 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). 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 mathema- tician Fra Luca Paciol 4,5 in 1496. Leonardo da Vinci (1452j1519) defined proportion as the ratio between the respective parts and the whole. 6 In 1946, Ghyka 7 showed several divine proportions in the face of a tennis champion, Helen Wills. Lombardi 8 was the first one to introduce the divine proportion to dentistry. In 1978, Levin 9 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 num- ber of golden proportions after examining the lateral and frontal cephalograms that he considered to be ideal. Amoric 11 also proved the existence of the divine proportion in many cephalometric mea- surements in different growth stages. In 2002, Baker and Woods 12 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, Marguardt 13 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 es- thetics, 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. CLINICAL STUDY 1946 The Journal of Craniofacial Surgery & Volume 24, Number 6, November 2013 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 Com- munity 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: Soheilsalari@gmail.com 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