Effect of maxillary incisor labiolingual inclination and anteroposterior position on smiling profile esthetics ABSTRACT Objective: To test the null hypothesis that there is no effect of maxillary incisor labiolingual inclination and anteroposterior (AP) position on smiling profile esthetics in young adult females. Materials and Methods: A facial smiling profile photograph of a Chinese woman with a normal profile, a Class I occlusion, and a Class I skeletal pattern was digitized. The digital image was modified to obtain four series comprising 29 smiling profiles. The sample of individuals rating these pictures comprised 21 orthodontic professionals and 66 undergraduates. Post hoc tests were done with the Student Newman Keuls method to analyze the data. Results: Significant differences (P , .001) were detected when each photograph’s ratings were compared. The smiling profile with the highest score was the one with 5u lingual inclination, while the ones with 15u labial inclination or 4-mm retrusion had lower scores than the others. Maxillary incisor protrusion and lingual inclination were preferable compared with retruded or flared incisors. There was no significant discrepancy between the professional and nonprofessional groups in terms of their assessments. Conclusions: The hypothesis is rejected. Both maxillary incisor labiolingual inclination and AP position play an essential role in the esthetics of the smiling profile. However, when formulating treatment plans, dentists should never underestimate the labiolingual inclination’s influence on the smiling profile. (Angle Orthod. 2011;81:123–131.) KEY WORDS: Esthetics; Incisor labiolingual inclination; Incisor AP position; Orthodontics INTRODUCTION Facial esthetics, in particular profile esthetics, is not only one of the motives that encourages most patients to seek orthodontic care but it is also one of the most important objectives of dental treatment.1–3 Although orthodontic treatment is based mainly on occlusal relationships, great attention has recently been paid to obtaining optimal facial profile esthetics.4 The potential effect of orthodontic treatment on facial attractiveness is accepted by most dentists.5 The literature also contains noteworthy studies6–8 that have shown comparable improvement in posttreatment profiles. However, it has been suggested9 that an ideal occlusion outcome does not necessarily result in desirable dentofacial features. And orthodontic treatment that adheres strictly to a cephalometric standard does not necessarily meet esthetic principles.10 When it comes to facial esthetics, not only should the tooth alignment and occlusion be closely monitored, but a thorough evaluation of the soft tissue–hard tissue relationship should also be included. 
Although the public is generally consistent with regard to what it believes constitutes an attractive face, public esthetic standards may well vary with time. In spite of the public’s emphasis on facial esthetic improvement, a reliable means to evaluate whole facial attractiveness does not exist.5 Esthetic standards, which are gradually established by the mass media, have a direct effect on orthodontics, orthopedics, and orthognathics. Thus, it seems worthwhile to clearly understand the social preferences related to dentofacial attractiveness and smile ‘‘pleasantness.’’ A smile is one of the most important facial expressions, and it is also indispensable in terms of expressing friendliness, approval, and appreciation. 11,12 Recently, smiling esthetics, especially frontal smiling esthetics, have been frequently studied.13–17 The soft tissue profile, including nose, lip, and chin, has received close attention as well.18, Evaluating the face in smiling profile is an integral part of a complete orthodontic diagnosis. Maxillary incisor labiolingual inclination and anteroposterior (AP) position have a key effect on the appearance of the smiling profile. To improve the prediction of the most proper position of the maxillary incisors, many cephalometric and profilometric measurements have been suggested. These include Andrews and Andrews20 six elements of orofacial harmony, for which the patient’s forehead is used as a stable landmark to decide the maxillary incisor AP position in smiling profile. However, there are no reports about the effect of the maxillary incisor labiolingual inclination on smiling profile esthetics. The aim of this study was to evaluate the effect of maxillary incisor labiolingual inclination and AP position on smiling profile esthetics in young adult females. MATERIALS AND METHODS 
Subject Selection Subject selection was restricted to the following criteria: (1) Class I occlusion and Class I skeletal pattern; (2) hard tissue cephalometric analysis (Winceph 7.0) within the normal range, as described in the West China Cephalometric Analysis; (3) soft tissue cephalometric analysis (including Ricketts’ esthetic plane,21 Merrifield’s z-angle,22 and measurement within the normal range); (4) facial angle and H angle within the normal range, as described by Holdaway,10 and nasolabial angle and maxillary lip angle within the normal range, as described by Arnett and Bergman23; (5) ideal maxillary incisor–to-forehead relationship, as described by Andrews and Andrews20; and maxillary central incisors’ facial axial point (FA) on the Goal Anterior Limit Line (GALL). A 25-year-old female graduate who met the above criteria was chosen from the West China College of Stomatology ( Image Alteration The subject’s repeatable smiling profile photograph was altered with the Photoshop CS2 (version 9.0) digital imaging program to obtain four series compris-ing 29 smiling profile photographs. The 100-mm ruler above the subject’s head was used to quantify hard and soft tissue movements and was later digitally removed to give the subject a normal appearance. The maxillary incisor labiolingual inclination was altered while FA was kept unchanged on GALL, as described by Andrews and Andrews.20 The maxillary incisor was inclined labially by 5u, 10u, and 15u and lingually by 5u, 10u, and 15u, respectively. There were seven images, including the original smiling profile photo, in the first series (Figure The maxillary incisor was moved in a horizontal plane with the incisor AP position altered. The maxillary incisor was moved anteriorly by superius at 1:3 to tooth movement.24 The smiling profile photo with maxillary incisor After all of the alterations, four series comprising 29 smiling profiles were printed. Each series was fixed with an erasable 100-mm visual analogue scale. The visual analogue scale was anchored by the descriptors ‘‘Least Attractive’’ (0) and ‘‘Most Attractive’’ (100). Visual analogue scales have been found25,26 to provide valid, reproducible, and representative ratings of dental and facial appearance. Judges An orthodontic professional panel ( 14 men , 9 women ) and a nonprofessional panel ( 33 men , 33 women ) were selected to judge the profile photographs . The ortho - dontic professional panel consisted of orthodontists who practiced in the orthodontic Department at the Rating of Photographs Each judge received the profile photographs while Seated and was asked to grade each profile based on h 15 Or her assessment Of the facial attractiveness of the subject , with the help of the 100 一mm visual analogue scales . Each judge was asked to rate the attractive - ness of the photographs on whatever criteria he or she thought important . The smiling profile photographs in each series were randomized before rating according to a random number table . The same observer gave the instructions for each of the study’s 87 sessions . SPSS (version 13.0) was used to analyze the data.The means of the raw data were determined in order to determine whether there were specific preferences for smiling profiles. The raw data were also analyzed with one-way analysis of variance (ANOVA). The factors were panel (professional and nonprofessional) and photograph (29 variations). Post hoc tests were done using the Student-Newman-Keuls (SNK) method. The level of significance was set at .05 for all statistical tests, unless otherwise stated. All altered pictures were divided into five groups according to whether the ratings were statistically significant or not per SNK analysis. RESULTS 
The subject used for photographic alteration exhibited excellent adherence to the accepted hard and soft tissue normative values. Her profilometric values were within the normal range (Tables 1 and 2), and the crown axial line of her central incisors was on GALL. She also had the ideal maxillary incisor-to-forehead relationship, as described by Andrews and Andrews20 (Figure 1). 
The means for the raw scores are summarized by panel and photograph in Table 3. Figure 3 represents the interaction bar plot, in which the x-axis represents the randomized photograph number and the y-axis represents the raw score. This graph shows the higher levels of acceptance for incisor protrusion and lingual inclination, compared with retruded or labially inclined incisors, in both panels. No significant difference was found in attractiveness ratings between the two panels. As might be expected, significant differences (P , .001) were detected when the ratings of each photograph were compared (Table 4). All altered pictures were divided into five groups by SNK analysis.
Harmonious Smiling Profiles The average scores of the relatively attractive group, Group 5 (Figure The harmonious smiling profiles above indicated that proper protrusion of maxillary incisors (FA ahead of GALL within Unharmonious Smiling Profiles The average scores of the unattractive group, Group 1 (Figure Those unharmonious smiling profiles above indicated that maxillary incisor retrusion of more than 
DISCUSSION The subject met the requirement of the relationship between the maxillary incisors and the forehead, as described in Element II of the six elements of orofacial harmony.20 Forehead was used as a landmark for assessing the AP position of the maxillary central incisors in smiling profile. The original photo had received a relatively high score, which caused us to think that the subject’s smiling profile was esthetic. Both images 29 (maxillary teeth in Of all the factors related to a balanced smiling profile, one can easily be controlled by orthodontists— the labiolingual inclination of the maxillary incisors. The expression of the incisor labiolingual inclination was influenced by various factors. However, most reports published on this issue indicate a loss of torque control of as high as 100% of the prescribed value.27 Based on the available evidence, Gioka and Eliades27 suggested that a high-torque prescription should be selected to account for the lack of full expression of the prescribed torque that occurs clinically. However, Isıksal et al. found that although the inclination values of the maxillary incisors were statistically different between extraction and nonextraction groups, the difference did not affect smiling esthetics in either group. Furthermore, increasing the labial inclination would cause smiling esthetics to deteriorate. The use of a hightorque bracket system, particularly in nonextraction treatment with anterior crowding, when initial tooth torques are close to the desired angles, would be inappropriate.28 Increased maxillary incisor labial inclination might also flatten the smile arc and reduce incisor display, which would lead to negative esthetic consequences.29,30 Our study corroborates these finding of others. Without exception, all of the images with 15° labial inclination of the upper incisors were considered less attractive. When it comes to the AP position of the maxillary incisors, the ratings also showed us that the raters had some tendency with regard to smiling profile esthetics. The attractiveness of the images was reduced with the increase in maxillary incisor retrusion. All the images with 2-mm retrusion were considered unattractive, in spite of the different labiolingual inclinations. Only one image with slight lingual inclination was acceptable. Many other studies also found that the fuller smile was more attractive.31 Schlosser et al.5 evaluated the effect of maxillary incisor AP relationship on smiling profile and found that the protrusion of the upper anterior teeth was more attractive than that of the retruded ones from an esthetic standpoint. This finding was consistent with that of our investigation. Thus, it is preferable to leave a normally protrusive maxillary dentition where it is, or else it is preferable to advance it rather than to retract the maxillary anterior teeth. Furthermore, each individual is a unique entity. When making treatment plans, it is essential that practitioners aim not only to achieve a normative dentofacial index, but also to consider the objective of obtaining a balanced smiling profile. The jaw size, the original labiolingual inclination of the maxillary anterior teeth, the AP position, and the soft tissue should be evaluated cautiously. Those patients with a Class III face type should be taken much more seriously in terms of increasing the maxillary incisor labial inclination to compensate for the underdevelopment of the maxilla and the upper alveolar bone, because the small amount of labial inclination increase of the upper incisors would have great negative influence on the attractiveness of the smiling profile. On the other hand, many patients with Class II face type can be treated with satisfactory esthetics through either dental arch expansion or tooth extraction, because there is an acceptable range of protrusion in our society. This is especially true if expansion is managed so as not to produce excessive labial inclination, or if extraction spaces can be closed without retracting the incisors too greatly.32 As facial esthetics becomes a more important objective in orthodontics, a better understanding of the beauty ‘‘tendency’’ can make it easier for clinicians to obtain the optimal smiling profile for patients. Maxillary incisors should be angulated and positioned favorably with regard to other facial structures in order to maximize facial harmony. CONCLUSIONS l A maxillary incisor that is upright or in slight lingual inclination is preferable, in spite of the AP position of the maxillary incisors. l Labial inclination of the upper incisors could easily ruin a pleasing smiling appearance. l Maxillary incisor protrusion is preferable to retruded incisors. l Element II of Andrews and Andrews six elements of orofacial harmony is a useful reference to the smiling profile esthetics in young adult women. ACKNOWLEDGMENT The study was supported by Technology Support Programs of Sichuan Province in REFERENCES 1. Andrews WA. AP relationship of the maxillary central incisors to the forehead in white females. Angle Orthod. 2008;78:662–669. 2. Dorsey J, Korabik K. Social and psychological motivations for orthodontic treatment. Am J Orthod. 1977;72: 460–467. 3. Kilpelanien P, Phillips C, Tulloch JFC. Anterior tooth position and motivation for early treatment. Angle Orthod. 1993;63: 171–174. 4. Isıksal E, Hazar S, Akyalc¸ın S. Smile esthetics: perception and comparison of treated and untreated smiles.Am J Orthod Dentofacial Orthop. 2006;129:8–16. 5. Schlosser JB, Orthop. 2005;127:17–24. 6. Bishara SE, Jackobsen JR. Profile changes in patients treated with and without extractions: assessments by lay people. Am J Orthod Dentofacial Orthop. 1997;112:639– 644. 7. Johnson DK, Smith RJ. Smile esthetics after orthodontic treatment with and without extraction of four first premolars. Am J Orthod Dentofacial Orthop. 1995;108:162–167. 9. SchabelaBJ,McNamara JA,Baccettic T, et al. The relationship between posttreatment smile esthetics and the ABO objective grading system. Angle Orthod. 2008;78:579–584. 10. Holdaway RA. A soft tissue cephalometric analysis and its use in orthodontic treatment planning, part I. Am J Orthod. 1983;84:1–28. 11. Peck S, Peck L. The gingival smile line. Angle Orthod. 1992; 62:91–100. 12. Tjan AH, Miller GD, The JG. Some esthetic factors in a smile. J Prosthet Dent. 1984;51:24–28. 13. Proffit WR. The soft tissue paradigm in orthodontic diagnosis and treatment planning: a new view for a new century. J Esthet Dent. 2000;12:46–49. 14. Yang IH, Nahm DS, Baek SH. Which hard and soft tissue factors relate with the amount of buccal corridor space during smiling. Angle Orthod. 2008;78:5–11. 15. Geron S, Atalia W. Influence of sex on the perception of oral and smile esthetics with different gingival display and incisal plane inclination. Angle Orthod. 2005;75:778–784. 16. Ioia H, Nakatab S, Counts AL. Effects of buccal corridors on smile esthetics in Japanese. Angle Orthod. 2009;79: 628–633. 17. Ritter DE, Gandini LG, Pinto Ados S, et al. Esthetic influence of negative space in the buccal corridor during smiling. Angle Orthod. 2006;76:198–203. 18. Bergman RT. Cephalometric soft tissue facial analysis. Am J Orthod Dentofacial Orthop. 1999;116:373–389. 19. Farkas LG, Katic MJ, Hreczko TA, et al. Anthropometric proportions in the upper lip–lower lip–chin area of the lower face in young white adults. Am J Orthod. 1984;86:52–60. 20. Andrews LF, Andrews WA. Syllabus of the Andrews Orthodontic Philosophy, 9th ed. 21. Ricketts RM. Planning treatment on the basis of the facial pattern and an estimate of its growth. Angle Orthod. 1957; 27:14–37. 22. Merrifield LL. The profile line as an aid in critically evaluating facial esthetics. Am J Orthod. 1966;52:804– 822. 23. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning, part I. Am J Orthod Dentofacial Orthop. 1993;103:299–312. 24. Garner LD. Soft-tissue changes and orthodontic tooth movement. Am J Orthod. 1974;66:367–377. 25. Knight H, Keith O. Ranking facial attractiveness. Euro J Orthod. 2005;27:340–348.
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