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Middle East J Rehabil Health. Inpress(Inpress): e34020. doi: 10.17795/mejrh-34020 Review Article Published online 2016 March 01. The Golden Proportion in Dentistry: A Literature Review 1 2 3 4,* Sina Pr oo f Amir Ali Karamifar, Mohammad Sadegh Nazari, Ali Hasani, Maryam Davari, 5 6 7 Kousha, Ali Mokhtar, and Isa Safari 1Orthodontics Department, Dental School, Semnan University of Medical Sciences, Semnan, IR Iran 2Tehran Dental Branch, Islamic Azad University, Tehran , IR Iran 3Oral and Maxillofacial Surgery Department, Tehran Dental Branch, Islamic Azad University, Tehran, IR Iran 4Prosthodontics Department, Dental School, Semnan University of Medical Sciences, Semnan, IR Iran 5Dental School, Semnan University of Medical Sciences, Semnan, IR Iran 6Orthodontics Department, Tehran Dental Branch, Islamic Azad University, Tehran, IR Iran 7Orthodontics Department, Dental School, Shahid Sadoghi Yazd University of Medical Sciences, Yazd, IR Iran *Corresponding author: Maryam Davari, Prosthodontics Department, Dental School, Semnan University of Medical Sciences, Semnan, IR Iran., E-mail: [email protected] Received 2015 November 8; Revised 2015 December 30; Accepted 2016 January 2. Abstract ct ed Context: In the last 2 decades, several studies have questioned the application of the rule of the golden proportion in dentistry. Therefore, the purpose of this review study was to assess the dental use of the golden proportion. Evidence Acquisition: We performed MEDLINE and Cochrane searches for English language literature published through 2015 using the following terms: golden proportion, golden ratio, and dentistry. Additional articles were then retrieved through hand searching the reference lists of the above articles. The manuscripts selected included review articles, systematic reviews, and meta-analyses. Results: The findings showed that the mean ratio of the relative widths of the central incisors, lateral incisors, and canines was 1.6:1:0.85 on both sides. The ratios were not influenced by either sex or previous orthodontic treatment. Conclusions: The results suggest that the rule of the golden proportion should not be used for treatment planning without observing individual modifying factors. Moreover, orthodontic treatment does not change the dentition toward the golden proportion. Keywords: Golden Proportion, Golden Ratio, Dentistry 1. Context C or re Aristotle pointed out the value of proportion in esthetics as early as the fourth century BC. The golden proportion was described by the Pythagoreans in the sixth century BC, and a little later by the Greek geometrician Euclid. However, long before the Greeks, the Egyptians had found and set up the golden number (1.618), and the width to length ratio in the Egyptian rectangle was 0.6 (ɸʹ) (1). The golden proportion was used in ancient Greek architecture to design the Parthenon, and can also be seen in da Vinci’s classical drawings of the human anatomy. This ratio is approximately 1.61803:1; that is, the smaller section is about 62% of the size of the larger. The uniqueness of this ratio is that the ratio of the smaller part to the larger part is the same as the ratio of the larger part to the whole (2). The golden proportion is also evident in the arts (3). Renowned artists such as Michelangelo, Raphael, and Leonardo da Vinci made use of this concept (4). For example, da Vinci drew the “ideal man” using the golden proportion, and the head of the Mona Lisa was drawn using this relationship. Moreover, evidence suggests that the classical music composed by Mozart, Beethoven, and Bach incorporated the golden proportion (5). Whether the use of the golden proportion by these artists and musicians was by design, intuition, or accident is not known. Ricketts devised a golden proportion caliper to establish and evaluate the ratios between various elements of the attractive face (6). Moreover, Lombardi was the first to propose the application of the golden proportion in dentistry, but he also stated, “it has proved too strong for dental use” (7). In addition, he defined the idea of a repeated ratio, which implies that in an optimized dentofacial composition from the frontal aspect, the lateral to central width and the canine to lateral width are repeated in proportion (7). Levin pointed out that “the width of the maxillary lateral incisor is in the golden proportion to the width of the central incisor and also the width of the maxillary canine to the lateral incisor when viewing from the front” (8). Preston measured 58 computer-generated images of dental casts with an image-measurement program, and evaluated the frequency of the golden proportion (considered to be in the range of 0.61 - 0.63) in the ratios of the perceived maxillary lateral to central incisors and canine to lateral incisors (9). He found that natural teeth were rarely in the golden proportion (17% maxillary lateral to central and 0% canine to lateral). He also reported that the mean perceived maxillary lateral to central incisor ra- Copyright © 2016, Semnan University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited. Karamifar AA et al. were studies concerning the golden proportion that were currently in progress. The papers were read by a team of researchers containing 2 orthodontists and a dentist, and the appropriate papers were accepted (Figure 1). The more reliable and more statistically significant studies from these papers are included in Table 1. This table also contains the historical development of the golden proportion in dentistry. Pr oo f 3. Results Based on the results of this study, the following conclusions were drawn: 1) The rule of the golden proportion is not valid for the examined populations. The mean ratio of the maxillary anterior teeth in people is 1.6:1:0.85. The canine is markedly wider than predicted by the golden ratio (1.6:1:0.6). 2) No sex-dependent or side-dependent variations in the width ratios of the maxillary anterior teeth were found. 3) In the examined population, the orthodontically treated participants did not exhibit a significant difference in the width ratios of the maxillary anterior teeth, when compared to the corresponding teeth of the untreated participants. The findings showed that the mean ratio of the relative width of the central incisors, lateral incisors, and canines was 1.6:1:0.85 on both sides. Moreover, the ratios were not influenced by either sex or previous orthodontic treatment. The rule of the golden proportion in dentistry is defined as follows: after measuring the width of the maxillary anterior teeth from the frontal view, and considering the width of the lateral incisor as 1, the width of the canine compared to that of the lateral incisor is 0.62, while the width of the central incisor compared to that of the lateral is 1.62 (9). In the 1960s and 1970s, several studies were conducted to find possible applications of the rule of the golden proportion in dentistry. Ricketts (16) was the first to define the application of the rule for the anterior maxillary teeth, stating that the application of the formula was indispensable in restorative and prosthetic dentistry. Magne et al. (18) also found a width/length ratio of 78% for the unworn central incisors; that is, the length was related to the width according to the rule of the golden proportion. The width to height ratio of the maxillary central incisors has been suggested to be significant in terms of the overall dental appearance, because these teeth normally dominate in a person’s smile (7). For the golden proportion, the width to height ratio of a maxillary central incisor crown would be equal to 0.62. The golden proportion takes into consideration the relative widths of the maxillary anterior teeth, and assumes that in attractive dentition the ratio of the apparent widths of the central incisor to the lateral incisor is 1.62:1; similarly, the apparent width of the lateral incisor is in the golden proportion to the width of the canine (i.e., 1:0.62) (8). The golden percentage is a modifica- re ct ed tio was 0.66, and the mean perceived maxillary canine to lateral incisor ratio was 0.84 (9). Gillen et al. in a study of 54 subjects, found that the golden proportion was rarely seen (10); however, their measurements were made directly on the casts, rather than on the frontal images. Snow stated that the concept of the golden percentage is a useful application in the diagnosis and development of symmetry, dominance, and proportion for an esthetically pleasing smile (11). Some other authors have also mentioned the use of this proportion in anterior esthetics (12, 13); for example, Rosenstiel et al. generated some computer images of the six maxillary anterior teeth, which had been categorized according to different tooth heights and proportions (14). The images were sent via e-mail to dentists in 38 countries to determine their esthetic preferences. It was reported that the dentists preferred the golden proportion when viewing very tall teeth, and that they considered this proportion less desirable for teeth of normal height or shorter teeth (14). Ward believed that when the golden proportion was used, the lateral incisor appeared too narrow, and the resulting canine was not prevalent enough (15). He preferred using the 70% proportion, and he also recommended adhering to the concept of the repeated ratio, which was defined by Lombardi in 1973 (7). In orthodontics, Ricketts (16) was the first to claim that the analysis of a physically beautiful face should be approached mathematically, and he advocated the use of the golden proportion in that respect. He observed dozens of photographs of magazine models to select pairs of distances representing the golden proportion in those beautiful faces. On this basis, he performed a small study using 10 beautiful faces and defined several golden proportions in them. Although objections were made against the study design (17), Ricketts’s articles (16) appear to be key publications in orthodontics and oral surgery for facial esthetics. Based on the above information, the purpose of this review study was to assess the rule of the golden proportion in dentistry. or 2. Evidence Acquisition C We performed MEDLINE and Cochrane searches for English language literature published through 2015 using the following terms: golden proportion, golden ratio, and dentistry. Additional articles were then retrieved through hand searching the reference lists of the above articles. The manuscripts selected included review articles, systematic reviews, and Meta-analyses. The inclusion criteria consisted of papers related to anterior esthetics and mouth rehabilitation, while the exclusion criteria consisted of papers not related to esthetic dentistry, such as articles about architecture, painting, and in vitro studies. We found 15 papers in the first step of searching the databases, but 2 papers were rejected. In addition, we searched “clinicaltrials.gov” to determine whether there 2 Middle East J Rehabil Health. Inpress(Inpress):e34020 Karamifar AA et al. not depend on any particular feature of the dentition. In a survey involving 301 dentists (21), it was found that the dentists preferred other esthetic design principles to that of the golden proportion. More recently, Baker and Woods (22) and Shell and Woods (23) were unable to establish significant correlations between changes in the golden proportion and changes in the esthetic ratings after orthognathic treatment. Although most of the subjects were considered to be esthetically improved after treatment, the proportions were equally likely to move away from or toward the golden proportion. Therefore, they concluded that the achievement of the golden proportion had little or no influence on the overall esthetic scores. Pr oo f tion of the golden proportion rule, and it was proposed as a simple and objective tool to assess such dental esthetic measures as anterior dominance, symmetry across the midline, and the regressive proportion (11). The largest study (19) conducted on this topic involved 376 dental students in Jordan. The authors found that the average ratio of the maxillary central incisor, the lateral incisor, and the canine was 1.53:1:0.8. Dimensions that corresponded to the rule of the golden proportion were found in only 31.3% of the women and 27.1% of the men (19). In addition, Ong et al. (20) conducted a survey with a selected sample of individuals who had to assess 60 different smiles on a 5-point Likert-type scale. Their results demonstrated that the overall dental attractiveness did Literature Published to 2015 Using Key Words: Golden Proportion, Golden Ratio, Dentistry ct ed Hand Search From the Reference Lists of the Above Articles for Additional Articles Selected Including Review Articles, Systematic Reviews and Meta-analysis re Inclusion Criteria: Papers Related to Anterior Esthetic and Mouth Rehabilitation 2 Papers Rejected or Found 15 Papers in the First Step of Searching the Database Exclusion Criteria: Paper not Related to Esthetic Dentistry, Such as Articles Main Concept About Architecture, Painting and Also in Vitro Studies Searched in the ‘Clinicaltrials. gov’ to Find Whether There are Studies Currently in Progress C Read Papers by Team Research Containing 2 Orthodontist and a Dentist Accepted the Appropriate Papers by Them Figure 1. Literature Review Procedure Middle East J Rehabil Health. Inpress(Inpress):e34020 3 Karamifar AA et al. Table 1. Studies of the Golden Proportion Reference Outcome Levin (8) In attractive dentition, the ratio of the apparent widths of the central incisor to the lateral incisor is 1.62:1; similarly, the apparent width of the lateral incisor is in the golden proportion to the width of the canine, that is, 1:0.62. Preston (9) Considering the width of the lateral incisor as 1, the width of the canine compared to that of the lateral incisor is 0.62, while the width of the central incisor compared to that of the lateral is 1.62. Snow (11) Magne et al. (18) Ali Fayyad et al. (19) Pr oo f The assigned values for the six anterior teeth were added (assigning 1.6 to the central, 1 to the lateral, and 0.62 to the cuspid). The width/length ratio was 78% for the unworn central incisors; that is, the length was related to the width according to the rule of the golden proportion. The average ratio of the maxillary central incisor, the lateral incisor, and the canine was 1.53:1:0.8. Acknowledgments The authors would like to thank the implant research center at the dental branch of the Islamic Azad University. Footnote Authors’ Contribution:Study concept and design: Amir Ali Karamifar, Maryam Davari, and Ali Hasani; acquisition of data: Mohammad Sadegh Nazari; analysis and interpretation of data: Mohammad Sadegh Nazari and Isa Safari; drafting of the manuscript: Mohammad Sadegh Nazari; critical revision of the manuscript for important intellectual content: Ali Mokhtar; statistical analysis: Mohammad Sadegh Nazari; administrative, technical, and material support: Sina Kousha; study supervision: Amir Ali Karamifar and Maryam Davari. or re ct ed A variation of the golden proportion was suggested by Snow (11), who proposed that the golden proportion could be used to develop symmetry, dominance, and proportion for aesthetically pleasing smiles. To simplify these proportions, the assigned values for the six anterior teeth were added (assigning 1.6 to the central, 1 to the lateral, and 0.62 to the cuspid). Then, the assigned width of each tooth was divided by the total to determine the relative percentage. The resulting percentages were: central incisor 25%, lateral incisor 16%, and cuspid 9%. These percentages illustrate the dominance of the central incisors, which are 50% of the cuspid to cuspid width. In fact, several studies have indicated that wide variation exists for patients and dentists with regard to the ideal anterior tooth proportions (14, 24, 25). In a study by Rosenstiel et al. (14), 549 dentists evaluated computer images of the same six maxillary anterior teeth. Those dentists preferred 80% proportions when viewing short or very short teeth, and the golden proportion (62%) for very tall teeth. There was no identifiable preference for teeth of normal length or tall teeth, and the choices could not be predicted based on gender, specialist training, experience, or patient volume. The results of a similar study by Kokich et al. (25) demonstrated that orthodontists, general dentists, and lay people detect specific aesthetic discrepancies at different levels of change. In the case of the golden proportion, the lay people did not discern a lateral incisor narrowing until the deviation reached 4 mm. 4. Conclusions C It is likely that patients who present for cosmetic rehabilitation will not be comfortable with some of the wide deviations identified in the previous studies. Nevertheless, these studies demonstrate that no single rule or formula can be used to generalize across a population. Overall, the results suggest that the rule of the golden proportion should not be used for treatment planning without observing individual modifying factors. Furthermore, orthodontic treatment does not change the dentition toward the golden proportion. 4 References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Beder OE. Esthetics—an enigma. J Prosthet Dent. 1971;25(6):588–91. doi: 10.1016/0022-3913(71)90120-x. [PubMed: 4929956] Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. Elsevier Health Sciences; 2006. Kappraff J. Connections: the geometric bridge between art and science. World Scientific; 2001. Kemp M. Spirals of life: D'Arcy Thompson and Theodore Cook, with Leonardo and Durer in retrospect. Physis Riv Internaz Storia Sci. 1995;32(1):37–54. Evans B. Number as form and content: a composer's path of inquiry. The visual mind. Cambridge: Leonardo Book Series, MIT Press; 1993. Ricketts RM. Divine proportion in facial esthetics. Clin Plast Surg. 1982;9(4):401–22. [PubMed: 7172592] Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosthet Dent. 1973;29(4):358–82. [PubMed: 4570911] Levin EI. Dental esthetics and the golden proportion. J Prosthet Dent. 1978;40(3):244–52. doi: 10.1016/0022-3913(78)90028-8. [PubMed: 279670] Preston JD. The golden proportion revisited. J Esthet Dent. 1993;5(6):247–51. [PubMed: 7993669] Gillen RJ, Schwartz RS, Hilton TJ, Evans DB. An analysis of selected normative tooth proportions. Int J Prosthodont. 1994;7(5):410–7. [PubMed: 7802908] Snow SR. Esthetic smile analysis of maxillary anterior tooth width: the golden percentage. J Esthet Dent. 1999;11(4):177–84. [PubMed: 10825874] Morley J. Smile design--specific considerations. J Calif Dent Assoc. 1997;25(9):633–7. [PubMed: 9534437] Ahmad I. Geometric considerations in anterior dental aesthetics: restorative principles. Pract Periodontics Aesthet Dent. Middle East J Rehabil Health. Inpress(Inpress):e34020 Karamifar AA et al. 15. 16. 17. 18. 19. 21. 22. tiveness. Am J Orthod Dentofacial Orthop. 2006;130(2):163–9. doi: 10.1016/j.ajodo.2005.02.018. [PubMed: 16905059] Ward DH. A study of dentists' preferred maxillary anterior tooth width proportions: comparing the recurring esthetic dental proportion to other mathematical and naturally occurring proportions. J Esthet Restor Dent. 2007;19(6):324–37. doi: 10.1111/j.17088240.2007.00114.x. [PubMed: 18005282] Baker BW, Woods MG. The role of the divine proportion in the esthetic improvement of patients undergoing combined orthodontic/orthognathic surgical treatment. Int J Adult Orthodon Orthognath Surg. 2001;16(2):108–20. [PubMed: 11482289] Shell TL, Woods MG. Facial aesthetics and the divine proportion: a comparison of surgical and non-surgical class II treatment. Aust Orthod J. 2004;20(2):51–63. [PubMed: 16429875] Wagner IV, Carlsson GE, Ekstrand K, Odman P, Schneider N. A comparative study of assessment of dental appearance by dentists, dental technicians, and laymen using computer-aided image manipulation. J Esthet Dent. 1996;8(5):199–205. [PubMed: 9468841] Kokich VO, Jr., Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental esthetics. J Esthet Dent. 1999;11(6):311–24. [PubMed: 10825866] 23. 24. 25. C or re ct ed 20. 1998;10(7):813–22. [PubMed: 10093545] Rosenstiel SF, Ward DH, Rashid RG. Dentists' preferences of anterior tooth proportion--a web-based study. J Prosthodont. 2000;9(3):123–36. [PubMed: 11179463] Ward DH. Proportional smile design using the recurring esthetic dental (red) proportion. Dent Clin North Am. 2001;45(1):143–54. [PubMed: 11210692] Ricketts RM. The biologic significance of the divine proportion and Fibonacci series. Am J Orthod. 1982;81(5):351–70. [PubMed: 6960724] Sinclair PM. Re: The divine proportion. Am J Orthodont. 1982;82(2):166–7. doi: 10.1016/0002-9416(82)90498-5. [PubMed: 6961790] Magne P, Gallucci GO, Belser UC. Anatomic crown width/length ratios of unworn and worn maxillary teeth in white subjects. J Prosthet Dent. 2003;89(5):453–61. doi: 10.1016/S0022391303001252. [PubMed: 12806322] Ali Fayyad M, Jamani KD, Agrabawi J. Geometric and mathematical proportions and their relations to maxillary anterior teeth. J Contemp Dent Pract. 2006;7(5):62–70. [PubMed: 17091141] Ong E, Brown RA, Richmond S. Peer assessment of dental attrac- Pr oo f 14. Middle East J Rehabil Health. Inpress(Inpress):e34020 5