|Year : 2015 | Volume
| Issue : 2 | Page : 65-68
Evaluation of smile esthetics by photographic assessment of the dento-labio-gingival complex
Mundoor Manjunath Dayakar1, Anna Shipilova1, M Rekha2
1 Department of Periodontics, K.V.G. Dental College, Dakshina Kannada, India
2 Department of Biostatistics, K.V.G. Dental College, Dakshina Kannada, Karnataka, India
|Date of Web Publication||11-Dec-2015|
Department of Periodontics, K.V.G. Dental College, Sullia, Dakshina Kannada, Karnataka
Source of Support: None, Conflict of Interest: None
Context: The esthetics of a smile is determined by various factors including symmetry, anatomy and position of teeth, periodontal visibility, and musculoskeletal relationships. Aim: This study analyzed the dento-labio-gingival esthetic components of the smile, evaluating: (a) Amount of gingiva visible during natural smile and forced smile, (b) relationship between incisal edges of maxillary anterior teeth and upper border of lower lip, (c) deviation of dental midline from facial midline to right or left side. Materials and Methods: Photographs of 127 subjects were taken by standardizing by placing patients head in Frankfurt horizontal plane and photos were cropped uniformly. Analysis of the dento-labial-gingival esthetic components of the smile, evaluating the relationship between the curve formed by the incisal edges of anterior teeth that is, incisal line and the curve of the lower lip, whether the incisal line touches the lower lip, presence of overlap of the lower lip over the incisal edges or absence of touch and also the amount of periodontal visibility during natural smile and the forced smile was done using Microsoft PowerPoint. Result: During natural smile the most frequent smile line was class 4 that is, low smile line seen in 67% of participants and class 3 for forced smile that is, average smile line seen in 44% of participants. There was a highly significant prevalence for females to have more periodontal visibility during both natural and forced smile (P < 0.001).40% of participants had maxillary incisor edges slightly apart from the lower lip and 48% of participants had maxillary incisal edges in light contact with lower lip. No significant difference was seen between the two genders (P > 0.05). 78 % of subjects showed no deviation from the midline, 19.7 % of the subjects showed the deviation of midline toward the right, and 2.4% showed deviation toward the left. Conclusion: Harmony of the dento-labial-gingival complex is essential for a pleasing smile. Evaluating the smile of each patient using photographs, as well as radiographs and clinical data assures the clinician of the possibility of deciding what needs to be carried out and what can be done to treat a gummy or an assymetrical smile according to its etiology.
Keywords: Dento-labio-gingival complex, smile arch, smile esthetics, smile line
|How to cite this article:|
Dayakar MM, Shipilova A, Rekha M. Evaluation of smile esthetics by photographic assessment of the dento-labio-gingival complex. J Dent Allied Sci 2015;4:65-8
|How to cite this URL:|
Dayakar MM, Shipilova A, Rekha M. Evaluation of smile esthetics by photographic assessment of the dento-labio-gingival complex. J Dent Allied Sci [serial online] 2015 [cited 2020 Sep 19];4:65-8. Available from: http://www.jdas.in/text.asp?2015/4/2/65/171515
| Introduction|| |
A person's smile can convey many different emotions and is a form of nonverbal communication.
The idea of an attractive smile varies between different cultures around the world as esthetic values and perceptions of beauty differ between esthetic groups and cultures.
In some cultures, a bright, wide, and symmetrical smile is typically considered to signify wealth, vitality, health, and success while in other parts of the world more emphasis is placed on the natural smile. 
Smile harmony is determined not only be the shape and contour, position in the arch and color of the teeth, but also by the surrounding gingival tissue, it's health, position of its margin, and it's visibility and also the dento-labial-gingival relationship.
This study analyzed the dento-labial-gingival esthetic components of the smile, evaluating the relationship of the curvature formed by the incisal edges of the maxillary anterior teeth with the curvature of the lower lip, whether this incisal line touches the lower lip or whether the maxillary incisal edges are overlapped by the lower lip during natural smile only and the amount of periodontal visibility during natural smile and the forced smile.
| Materials and Methods|| |
One hundred and twenty-seven participants in this multi-center study comprised patients of dental camps held in Dakshina Kannada. Informed consent was obtained from all the participants for the study. Inclusion criteria for the study were the following:
- Age more than 21 years;
- At least 8 contiguous anterior preferably, equally and symmetrically distributed between right and left side; and
- A healthy periodontium or a reduced and healthy periodontium.
Patients were excluded if they had prosthesis because this might have affected esthetics or health of the periodontium. Gender and age of each patient participating in the study were recorded.
All the participants were photographed to evaluate their smile line. Two different pictures were taken of all participants in the study: One during a natural smile, and one during forced or maximal smile. The amount of periodontal visibility during natural and forced smile was determined from the pictures [Figure 1]a and b.
The pictures were standardized as per Liebert et al., by positioning the head in the Frankfurt horizontal plane and taking the picture from distance of 30 cm so as to include the lateral commissures of the mouth, the teeth, gingiva, and the philtrum of the upper lip.
The smile lines were analyzed using the classification used by Liebert et al. 
- Type 1 - Very high smile line: 2 mm or more of marginal and attached gingiva visible or more than 2 mm of root or gingiva apical to the cemento-enamel junction visible for the healthy but reduced periodontium. This smile is classified as "gummy smile".
- Type 2 - High smile line: Between 0 and 2 mm of marginal and attached gingiva visible or between 0 and 2 mm visibility of root and gingiva apical to the cemento-enamel junction visible for the reduced and healthy periodontium.
- Type 3 - Average smile line: Gingival embrasures only visible.
- Type 4 - Low smile line: Gingival embrasure and cemento-enamel junction not visible [Figure 2] a-d.
|Figure 2: (a) Very high smile line (b) high smile line (c) average smile line (d) low smile line|
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All the smiles were also evaluated for the midline of the dental arch and for the relationship of the smile arch to the upper border of the lower lip. This was done using Microsoft PowerPoint.  A line was drawn through the dental midline. Two lines were then drawn from this line to both the left and right borders of the philtrum which was taken as the facial midline. The length of these lines from the dental midline was observed to evaluate whether the dental midline is deviated toward the right or left side.
The chi-square test was used to compare the type of smiles in males and females with the level of significance taken as 5%.
| Results|| |
The sample consisted of 127 subjects of which 77 were females, and 50 were males. The age of the subjects ranged from 22 to 64 years, and the mean age was 34.17 years [Figure 3].
Type of smile line
During natural smile, the most frequent smile line was class 4 that is, low smile line seen in 67% of participants.
During forced smile, the most frequent smile line was class 3 that is, average smile line seen in 44% of participants.
There was a highly significant prevalence for females to have more periodontal visibility during both natural and forced smile (P < 0.001).
Of the total participants who had high smile line during a natural smile, 85.1% were females and 14.9% were male.
Of the total participants who had low smile line during a natural smile, 38.8% were female and 61.2% were males [Figure 4] and [Figure 5].
|Figure 4: Bar diagram showing distribution of smile lines among males and females|
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|Figure 5: Bar diagram showing distribution of smile lines amongst males and females during forced smile|
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Relationship between smile arch and curve of lower lip
A 40% of participants had maxillary incisor edges slightly apart from the lower lip, and 48% of participants had maxillary incisal edges in light contact with lower lip [Figure 6].
|Figure 6: Bar diagram shows relationship between smile arch and curve of lower lip|
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No significant difference was seen between the two genders with regard to the relationship between smile arch and the curve of the lower lip (P > 0.05).
The prevalence of the smiles with incisal edges touching and or not touching the lower lip was higher than the prevalence of the smile with the lower lip overlapping the maxillary incisors and the difference was statistically significant (P > 0.05, P > 0.05 respectively). No statistically significant difference was observed in the prevalence of smiles with maxillary incisors touching or not touching the lower lip.
Deviation of midline of dental arch from facial midline
A 78% of subjects showed no deviation from the midline, 19.7% of the subjects showed the deviation of midline toward the right, and 2.4% showed deviation toward the left [Figure 7].
|Figure 7: Bar diagram showing relationship between dental and facial midline in males and females|
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The esthetics of a smile can be evaluated from various perspectives. Several esthetic components of the dento-labio-gingival complex have been evaluated in this study.
The smile line is considered to be a valuable tool to assess the esthetic appearance of a smile as clinicians and laypersons have been found to perceive it similarly.  Various factors such as gingival architecture and tooth length are important determinants of an esthetically pleasing smile  and contribute to the amount of gingiva visible while smiling. Furthermore, variables such as upper and lower lip muscle mobility, strength, vertical length of the lip, clinical crown length, and skeletal relationship, especially vertical maxillary length can lead to variation in the amount of dental and gingival exposure during speech and smile in different persons.  Various conditions such as malpositioning of teeth, altered passive eruption, recession, and loss of interproximal papilla leads to an unesthetic appearance. 
The present study showed variation in periodontal visibility during natural smile and forced or maximal smile in both genders. 81.8% females were found to have a high smile line during natural smile whereas only 18.2% males were found to have a high smile line during a natural smile.
A similar pattern was seen during forced smile: 76.2% females exhibited a high smile line as compared to 23.8% males.
Several studies on various populations have reported a higher percentage of women had a high smile line and a very high smile line as compared to males. , The results of this study are consistent with these findings.
The most frequent smile line for natural smile was low smile line (52.8% of participants), consistent with findings of Sepolia et al. 2014  and the most frequent smile line during forced smile was the average smile line, this finding being consistent with Liebert et al.
There should be harmony between the curvatures of the incisal edge of the anterior teeth with the lower lip. This relationship of the incisal edges of maxillary anteriors with lower lip is called smile arch. The ideal is for the incisal edges to be parallel to the upper border of the lower lip and a few millimeters apart from it or softly touching the lower lip. This is achieved when dental and labial structures are symmetrical.  This relationship of the lower lip to the incisal edges of the maxillary anteriors depends on mouth opening and muscle contraction of the lower lip. Facial muscles including mentalis, insicivus inferior, risorius, triangularis and quadratus labii superioris, and quadratus labii inferioris of the lower lip are involved in the contraction of the lower lip and their degree of participation during smiling interferes in contraction of the lip and it's symmetry.  The configuration of smile arch has also been described as: Convex arc, curved arc, consonant arc, and deep plate-shaped arc. Inverted ach and the reverse arc is seen in subjects in which incisal edges do not touch the lower lip.  In this study, the prevalence of the smiles with maxillary incisal edges touching or not touching the lower lip was higher than the prevalence of the smile with the maxillary incisors overlapped by the lower lip which was statistically significant. Of these, 48% participants had maxillary incisor edges in light contact with the lower lip. This is consistent with the study by Tjan et al. (1984). 
In this study, the position of the midline of the dental arch was analyzed, considering the filter of the lip as reference. No significant difference was seen in the prevalence of the situation of the midline, either centralized or moved to the right or left side.
According to Tjan and Cavalcante and Pimenta the midline of the dental arch should be centrally situated in the smile to have greater harmony. ,
Johnston et al. stated that a dental to facial midline discrepancy more than 2 mm is esthetically unacceptable. 
The majority of the subjects showed no deviation of dental to facial midline (78%).
| Conclusion|| |
Health and harmony of the dento-labial-gingival structures are essential for a pleasing smile. Knowledge of the dento-labial-gingival characteristics of the smile helps in the esthetic percipience of it by the clinician.
The present study was done to evaluate some aspects of the dento-labial-gingival complex using photographs.
Evaluating the smile of each patient using photographs, as well as radiographs and clinical data assures the dentist of the possibility of deciding on the treatment options and to implement an interdisciplinary approach to treat a gummy or an assymetrical smile according to its etiology.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]