| Abstract|| |
Background: Dental students in their clinical years are part of the dental workforce. The ability of the graduate to identify patient's aesthetic requirements and determine the degree to which those requirements or desires can be met is one of the new dentist's competencies. The perception of dental students toward some esthetic factors of smile was investigated and compared to that of pharmacy students in the same university.
Materials and Methods: The authors developed a booklet of smile comprised of an ideal smile and seven altered smiles involving change in shade, shape, width and length of teeth in addition to midline shift and change in the gingival display. Students rated ideal smile and altered smiles using a 100-point visual analog scale (VAS).
Results: The study involved 198 students; 108 dental students and 89 pharmacy students and 131 females and 66 males. Mean values for the VAS for the ideal smile were 72, 66 for dental and pharmacy students, respectively. While the mean values for the altered smiles varied between 23 and 65. Ideal smile was rated significantly higher by dental students (P = 0.015) Dental students rated midline shift change in gingival display, alteration in size and shape significantly lower than pharmacy students. While no significant difference was detected between the pharmacy students' ratings of the ideal smile and alterations in shape, size, clinical crown and gingival display.
Conclusion: Dental students are more receptive to smile alterations. Dental students appreciated the ideal smile more than pharmacy students. Darker tooth shades, spacing and midline shift were least accepted by both dental and pharmacy students. Dental students were more sensitive to changes in gingival display, crown length, lateral incisors width and shape while pharmacy students were more tolerant to these changes.
Keywords: Aesthetics, dental students, smile perception
|How to cite this article:|
Omar H, Tai YT. Perception of smile esthetics among dental and nondental students. J Educ Ethics Dent 2014;4:54-60
|How to cite this URL:|
Omar H, Tai YT. Perception of smile esthetics among dental and nondental students. J Educ Ethics Dent [serial online] 2014 [cited 2019 Sep 21];4:54-60. Available from: http://www.jeed.in/text.asp?2014/4/2/54/148986
| Introduction|| |
Enhancing and promoting total health of patients through management of oral health is the primary goal of dentists and dentistry. Competent practitioners should obtain a complete understanding of the situations where intervention should be done and situations where patient's referral is appropriate or when no intervention is needed. The professional development of the dental student is a continuous process; starts the day he/she joins the dental school and ends when the dentist retires from the profession. The first milestone in the professional development journey of the dentist is obtaining the first degree. Competencies are defined as the abilities essential for the dental graduate to begin the practice of dentistry.  The General Assembly of the Association for Dental Education in Europe and American dental Education Association in North America had identified the core and supporting dental competencies that a graduate dental student should obtain. , Among the dental graduate competencies stated, was the ability of the graduate to identify patient's aesthetic requirements and determine the degree to which those requirements or desires can be met. ,, Incorporation of this competency is based on the fact that esthetic dentistry is a fast growing dental field and that the demand for elective and cosmetic procedures is continuously increasing. ,
Physical attractiveness is considered as an integral part in social interaction. Facial composition as a part of the person's physical attractiveness is an important social issue in most cultures as it represents the key feature in personality evaluations, performance, and interpersonal success in settings such as school and employment. , Face was reported to be the most important factor that determines the aesthetic perception of a person and during interpersonal interaction focus is mainly on eyes and mouths. In the face the smile ranks second to the eye as the most important feature in facial attractiveness and the importance of the mouth represented 31% while the eyes represented 34%. ,,, According to a meta-analytic review conducted by Langlois and colleagues, it was concluded that attractive children and adults receive more positive judgments and academic and performance reviews than do unattractive individuals. This results in greater self-confidence among attractive individuals. 
Recently, pleasant dental esthetics represents a main concern for patients and dentists and it is a contributing factor for physical well being of individuals.  Smile is one of the most important determinants of dental aesthetics. Smile esthetics was found to be the primary reason for patients to seek aesthetic and orthodontic treatment. ,, Kiyak studied the effects of orthodontic treatment on patients' quality of life and reported that patients who seek orthodontic and aesthetic treatment wish to improve their esthetics and social acceptance more than oral function or general health. 
Inter-personal variations in esthetics perception among individuals are influenced by their personal experience and social environment. Hence, the opinions of professionals in respect to evaluation of esthetics may not coincide with that of patients or laypersons.  Assessment of perception of smile esthetics of general practitioners, orthodontists and laypersons had been investigated in the literature under varying methodologies and results. ,,,
Dental students represent part of the dental workforce, and they should be able to identify patients' needs and expectations, make clinical decisions pertaining dental esthetics and the needs to intervene or refer. Literature provides minimal information regarding the perception of smile esthetics of dental students when compared to laypersons.
The use of digitally modified pictures to obtain the perception and to assess esthetics and smiles is well reported in the literature. ,,, Visual Analogue Scale (VAS) is used as a measurement tool that can be applied to evaluate perceptions.  The VAS is characterized by being simple to administer, reliable and valid tool to assess perceptions.  The use of VAS to assess dental appearances is commonly used in the literature. ,,
Evaluation of the perception of the smile in this study was based on assessing images showing only smiles and evaluation was done using a VAS.
This study was conducted to evaluate and compare the degree of perception of the aesthetic discrepancies in the smile by dental students and laypersons represented by pharmacy students of different gender.
| Materials and Methods|| |
The study involved the use of smile images that was altered using computer software. Visual Analogue Scale (VAS) was used as a measurement tool to evaluate perceptions towards the smiles.
Construction of booklet of smile images
The study identified an image of a colored-smile that possessed criteria of an ideal smile in terms of geometric concepts, dental, dentofacial and gingival aspects of dental aesthetics.  The image chosen for this study was a frontal view showing the anterior teeth, the surrounding gingival tissues and lips. The image was cropped to remove the chin, nose and cheeks in order to reduce the confounding factors that may affect the perception of the smile.
The ideal smile was altered to produce seven more images with common anterior aesthetic discrepancies in shape, shade, size, crown length, spacing midline shift and gingival position using Adobe Photoshop software. 1 The degrees of deviation from the ideal smile chosen in this study were based on acceptable amounts of deviation proposed by other similar studies. ,
Each image was altered to achieve one discrepancy from the ideal. Altered crown shape was obtained by the rounding of the angels of the central incisors. Changes in the shade were carried out by darkening the teeth toward the grayish color. The size of maxillary lateral incisors was altered digitally to obtain a 52% lateral-to-central width proportion in contrast to the ideal smile the followed the golden-proportion (62%). To alter the length of the central incisors it was reduced by 2 mm. Regarding the midline shift and the spacing, 2 mm midline shift toward the patient's right and a midline spacing (diastema) of 2 mm were created through the software, respectively. Gingival display was increased by 2 mm to obtain a total gingival display of 5 mm. Gingival display was measured from the lower border of the upper lip till the gingival margin of the tooth. All the images are presented in [Figure 1].
|Figure 1: (a) The ideal smile, (b) The altered crown shapes,(c) Altered shade of the crowns, (d) Reduced size of maxillarylaterals, (e) Altered length of maxillary incisors, (f) Midline shift,(g) 2 mm diastema, (h) Increased gingival display|
Click here to view
Size of the created images was adjusted to represent the actual size of teeth. The images were given the alphabets from A-H and each image was pasted in the center of an A4 paper. A booklet was created with the images arranged randomly with the ideal smile represented the fifth image. An additional page that showed a visual analog scale was given separately to each participant. The page contained eight visual analogue scales (VAS) given the alphabets A-H. Each scale is 10 cm long and starting from 0 that represent the least attractive smile and ending at 100 representing the most attractive smile.
Prior to the study the clarity of the images and the instructions were piloted on seven medical students from the same university and feedback regarding sharpness of images, clarity of instructions was obtained and addressed accordingly.
This cross-sectional study was carried out among dental and pharmacy students enrolled in a private university in Malaysia. The number of dental students and pharmacy students enrolled in the university was 128 and 102, respectively. Sample size calculation was based on confidence interval 95% and margin of error 5% and it was found to be 97 for dental students and 81 for pharmacy students.
The study was approved by the research ethics committee of the university. Dental and pharmacy students were invited to participate in the research. Class representatives of both dental and pharmacy batches were approached to identify the slots in the timetables and the participants can be approached to ensure the maximum response rate. An informed consent was obtained from all the students who agreed to participate.
Booklets were distributed to the students who agreed to participate and they were asked to view each image for 20 s without being able to revaluate previously seen images as suggested by Flores et al.  The smile attractiveness was evaluated using the visual analogue scales provided.
Data were entered and analyzed using the statistical package for social services (SPSS) for windows software. Descriptive data for categorical variables were obtained through frequencies, while the descriptive data for continuous variables were obtained through mean and standard deviation (SD). Cronbach's alpha coefficient was used to measure the internal consistency of the scale.  The study involved the use of one-way ANOVA to analyze the perception of dental and pharmacy students toward the ideal smile and multivariate analysis of variance (MANOVA) to analyze their perception toward the altered smiles.
MANOVA is an extension of analysis of variance for use when more than one dependent variable is involved. The level of significance was set to 0.05 (95%) CI.
| Results|| |
The total number of participants was 197 students. A total of 108 dental students participated in the study with a response rate of 85 % and 89 pharmacy students with a response rate of 87%.
Descriptive data from the evaluators represented by the gender and the field of study are presented in [Table 1].
Mean and standard deviation of the VAS (100-mm scale) rating from the different smiles were presented in [Table 2] and results for pharmacy and dental students are presented in [Table 3].
|Table 2: VAS values for the ideal and altered smiles. For|
both dental and pharmacy students
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|Table 3: VAS values for the ideal and altered smiles|
by dental and pharmacy students
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In this study Cronbach's alpha coefficient was measured to determine the reliability of the scale and it was found to be 0.832. This value is considered preferable and showed good internal consistency.
The VAS values representing the aesthetic perception of dental and pharmacy students toward the identified ideal smile was statistically analyzed using a one-way ANOVA and results revealed no significant difference in the perception of males and females and relation to their rating of the ideal smile (P = 0.851) but in relation to the field of study significant difference was detected between the perception of dental students and that of pharmacy students in regards to the ideal smile (P = 0.015). The VAS means for the pharmacy students was 66 while that of dental students was 72 [Figure 2].
The VAS scale representing the aesthetic perception of dental and pharmacy students toward the altered dental smiles was statistically analyzed using MANOVA. Prior to analyzing the results using MANOVA preliminary analysis steps were conducted to identify outliers and assess assumptions for the MANOVA procedure.
MANOVA results revealed no statistical significant difference between the VAS values for the two genders (P = 0.554) and statistical significant difference between the VAS values of dental and pharmacy students toward the altered dental smiles (P = 0.001).
A statistical significant difference was found between the VAS mean values of dental and pharmacy students in relation to midline shift (P = 0.001), gingival position (P = 0.021), size and shape of the teeth (P = 0.001).
In regards to pharmacy students' ratings, there was no significant difference between their rating of the ideal smile and smiles with increased gingival display, short clinical crown, altered size and shape (P = 0.564). While a significant difference was detected between the rating of the ideal smile by the dental students and their rating of the seven altered smiles (P = 0.001).
Mean VAS values for the dental and pharmacy students for the altered smiles are presented in [Figure 3].
|Figure 3: Visual analog scale means of dental and pharmacy students for the various altered dental smiles|
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| Discussion|| |
The results of the present study highlight the difference between the aesthetic perception of dental and non-dental students toward smiles. Two groups of raters were used in this study: Dental students and pharmacy students. The students rated an ideally aesthetic smile and seven aesthetically altered smile images. The study represented smile images as "close up" views rather than a full smiling face as it was reported that lay people are more aware of dental esthetics when represented as a "close up" views. 
No significant difference was detected between ratings of increased gingival display, short clinical crown, altered size and shape when compared to that of the ideal smile by pharmacy students. This finding indicates that pharmacy students are more tolerant to those changes. Dental students showed receptiveness toward the seven altered dental smiles as they rated them significantly lower than the ideal smile. Those results indicate that dental students were sensitive to esthetic factors affecting the dental smile and they seemed to be less tolerant in their evaluation regarding some smile aspects more than pharmacy students. Similar results were obtained by studies that assessed the perception of laypeople and dental professionals. ,
In this study the ideal smile was rated at a mean of 70 on a VAS, where dental students rated the smile at a mean of 72 and pharmacy students rated it at a mean of 66. The difference between the dental and pharmacy students' rating was found to be significant. The fact that the dental students had much higher opinion in regards to the ideal smile is interesting. The higher rating of the ideal smile by dental students can be attributed to their theoretical and clinical background in relation to dental esthetics and their understanding of the dental factors affecting the smile. The increased appreciation of the ideal smile by dental students can be attributed to the presence of 3 mm gingival display that was reported as unfavorable to laypeople that preferred no gingival display. 
Regarding the results of altered smiles, the image that displayed the smile with the darker tooth shade - towards grey - was the image least accepted by both dental and pharmacy students. The mean for the two groups of raters was 23 on the VAS. The importance of tooth shade as one of the main aesthetic determinants of smile and favoring of smiles that feature teeth with light shade was supported in the literature. ,,
Results of this study revealed that both groups; dental students and pharmacy students were sensitive to changes in shade and were less forgiving toward dark tooth shades. The participants of this study belong to a young age group and the finding represented by lower rating of dark teeth lend some support to previously conducted aesthetic surveys were younger individuals showed greater preference for white teeth than older subjects. ,
On the other hand, a study conducted by Grosofsky and colleagues reported that manipulation of teeth shade did not influence the ratings of attractiveness of smile. The variation between the results obtained in the current study and Grosofsky study can be attributed to their use of images showing head and shoulder with subsequent involvement of more factors affecting the assessment of attractiveness. 
In relation to midline spacing (diastema), results revealed no significant difference between VAS mean values for dental and pharmacy students with a mean value of 37. Midline spacing was rated in this study as the second least attractive factor affecting smile aesthetics. Results of this study were in contrast to results obtained by Rosenstiel and Rashid in 2002, where the authors reported that public showed strong preference concerning midline spacing.  The difference between the results of the current study and Rosenstiel's study can be attributed to cultural preference amongst the participants in both studies. It was reported that across cultures there are differences in smile attractiveness ratings and midline spacing of 1-1.5 mm was found to be significantly less attractive by Caucasians when compared to Middle Easterners. 
The third least attractive smile was the one that showed a 2 mm midline shift and results showed significant difference between dental and pharmacy students' ratings for that image. Dental students were more sensitive to midline shift than pharmacy students. In spite of that significant difference, results showed that both dental and pharmacy students were sensitive to 2 mm midline shift.
Results of this study were close to findings of another study that reported that a midline shift of 2-mm was perceived by 83% of orthodontists and dental professionals and 56% of laypersons. 
Considering a 2 mm diastema as the threshold for general dentists and laypeople was reported in a study conducted by Kokich and colleagues.  In contrast to our findings, two studies reported that there is lack of perception of dental midline asymmetries by laypersons and that a midline shift less than 4 mm has no impact on the aesthetic perceptions. , As mentioned earlier the discrepancies within the results of various studies can be attributed to several factors including methodologies, statistical tests, cultural backgrounds and manipulation of smile images.
In regards to images displaying altered gingival display, length of crowns, size and shape of teeth, the ratings showed a degree of closeness with VAS mean values of 64, 64, 62 and 60, respectively. Pharmacy students rated the images of those altered smiles significantly higher than dental students.
Gingival display as one of the factors affecting the smile esthetics has been investigated in the literature with varying results. ,, In a series of studies conducted by Kokich and colleagues investigated the gingival display, the authors reported that 4 mm of gingival display represent the threshold of acceptability.  In a later study the authors agreed that threshold of acceptability is 3 mm.  Ker and colleagues in a more recent study reported that the ideal gingival display is 2.1 with an acceptable range of 4 mm. In our study the gingival display of the ideal smile was 3 mm and the altered smile showed a gingival display of 5 mm.
Perception toward the length of the crowns of maxillary central incisors was assessed in this study, the crowns were shortened by 2 mm and pharmacy students rated the reduction in the crown length significantly higher than dental students. A reduction of crown length by about 2 mm was reported to be accepted by laypeople in case of asymmetric crown length. Dental students' sensitivity toward the bilateral reduced central incisors crown length was comparable to that of general dentists who detected discrepancies of 1.5-2 mm in a similar study. 
In relation to size of teeth, the maxillary lateral incisors' size was altered to obtain 52% lateral-to-central width proportion. Dental students were more sensitive to this change in width proportion. The results of this study were comparable to that of another study conducted by Bukhary and colleagues as they reported that dentists were more receptive to the reduced lateral-central width proportion. 
This study involved investigating the effect of gender on esthetic perceptions and it was found that there was no difference in esthetic perceptions toward ideal smile and altered smiles between males and females. These results were similar to those reported in Bukhary's study. 
Due to the variation in the studies addressing the perception of smile aesthetic, there is a certain degree of difficulty in comparing the perception of smile across studies as there is different analytical methods and data collection instruments amongst studies, incorporation of various methodologies; web-based surveys, self-reported perception, photographs and software altered images, involvement of a wide range of smile aspects and different sociocultural aspects. This discussion will address the findings of other related studies whenever possible.
Dental students in their clinical years should be encouraged to discuss these differences with the patients in perception when planning esthetic treatments. Understanding that there is a difference in the esthetic perception between professionals and laypeople is important to address patient's needs and expectations in regards to esthetics.
The results of the study show that dental students are generally more receptive to smile alterations. Dental students appreciated the ideal smile more than pharmacy students. Darker tooth shades, spacing and midline shift were least accepted by both dental and pharmacy students. Dental students were more sensitive to changes in gingival display, crown length, lateral incisors width and shape while pharmacy students were more tolerant to those changes.
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Asst. Prof. Hanan Omar
School of Dentistry, International Medical University, 126 Jalan Jlail Perkasa 19 – Bukit Jalil - 57000 KL
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]