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Table of Contents   
ORIGINAL RESEARCH  
Year : 2021  |  Volume : 32  |  Issue : 2  |  Page : 167-173
Evaluating upper lip changes during smiling and at rest in Indian population


1 Dental Officer and Orthodontist, Department of Orthodontics and Dentofacial Orthopedics, Army Dental Corps., Tezpur, Assam, India
2 Department of Orthodontics and Dentofacial Orthopedics, Army College of Dental Sciences, Secunderabad, Telangana, India
3 Department of Prosthodontics, Crown and Bridge, Institute of Dental Studies and Technologies, Modinagar, Uttar Pradesh, India

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Date of Submission16-Aug-2018
Date of Decision29-Jun-2019
Date of Acceptance22-Nov-2020
Date of Web Publication22-Nov-2021
 

   Abstract 


Context: Smile aesthetics is one of the major goals to be achieved after orthodontic mechanotherapy as it visibly displays the results of orthodontic treatment. Although orthodontic retainers aid in maintaining post-treatment occlusion, soft tissue function and aesthetics, appropriate knowledge of smile changes with age can help orthodontists to obtain stable and aesthetically appealing treatment results. Aim: To assess and quantify soft tissue changes in the upper lip in vertical dimension at both repose and maximum smiling and to evaluate changes occurring with the smile index and upper lip with age and sex in subjects of Indian origin. Settings: Department of Orthodontics and Dentofacial Orthopaedics, Army College of Dental Sciences, Secunderabad, Telangana, India. Design: Observational study Methods and Materials: A total of 160 volunteers (80 males and 80 females) selected and were divided into 4 groups according to age and were further divided into 2 sub-groups according to gender. Thirteen measurements of relaxed and smiling upper lip were taken with a calibrated metal ruler and divider directly on the subjects. Statistical Analysis Used: Analysis of variance (ANOVA) was done followed by post hoc test to determine which groups were significant from others. Levene's test was done to assess equality of variance and t-test for equality of means was done. Results: Statistically significant results were obtained in between groups and sub-groups for parameters like smile index, upper lip elevation while smiling and smile pattern in males and females changing with increase in age. Conclusions: High smile patterns with more vertical smile are more common among females and low smile patterns are more common among males. With age, the smile tends to be more horizontal in both genders.

Keywords: Central incisor length, smile index, smile pattern, upper lip length

How to cite this article:
Dahiya S, Negi G, Dahiya K, Mathur AK, Chitra P. Evaluating upper lip changes during smiling and at rest in Indian population. Indian J Dent Res 2021;32:167-73

How to cite this URL:
Dahiya S, Negi G, Dahiya K, Mathur AK, Chitra P. Evaluating upper lip changes during smiling and at rest in Indian population. Indian J Dent Res [serial online] 2021 [cited 2021 Dec 8];32:167-73. Available from: https://www.ijdr.in/text.asp?2021/32/2/167/330859



   Introduction Top


Facial soft tissue changes achieved during orthodontic therapy form an important aspect of gauging overall treatment success. One major soft tissue change noticeable post orthodontic therapy is improved smile esthetics. The three primary components essential for an esthetic smile are the teeth, lip framework and gingival scaffold.[1] A pleasing smile involves a harmonious relationship between these components, therefore, it is of major interest among practitioners and plastic surgeons. It is mandatory to analyse soft tissue as well as hard tissue in three dimensions: transverse, sagittal and vertical, while developing an appropriate treatment plan for the patient along with time which has been recognized as the fourth dimension.[2],[3] Aesthetics in orthodontics has been defined mainly in terms of profile enhancement, but if lay people are asked what an orthodontist does, their answers will usually include something about creating beautiful smiles.[2]

Human smile patterns have been classified by prosthodontists and orthodontists[4],[5] as being either low, average or high.[6] An incisor exposure of 75% or less is considered as low smile, 75–100% of exposure is an average smile and an incisal exposure of 100% with gingival show is defined as a high smile. It has been observed that bony and dental tissues undergo changes with age that have direct effects on the overlying soft tissues. Age related effects on the hard and soft facial structures and the smile pattern require detailed investigation to obtain predictable treatment outcomes.[7] Thus, the purpose of this study was: To assess and quantify soft tissue changes in the upper lip in vertical dimension at both repose and maximum smiling and to evaluate changes occurring with the smile index and upper lip with age and sex in subjects of Indian origin.


   Subjects and Methods Top


Volunteers numbering 160 (80 males and 80 females) were selected from nearby residential areas. The study protocol was approved by the Institutional Ethics Committee of Army College of Dental Sciences, Secunderabad (approval no: ACDS/IEC/11/Dec 2016). Written informed consent was obtained from all participants prior to evaluation.

Subjects included in the study were in Class I incisor relation without crowding or spacing. Individuals who underwent visible prosthodontic treatment in the smile zone, had a history of ongoing or completed orthodontic/endodontic treatment, craniofacial deformities, missing teeth visible during smiling and teeth showing signs of attrition and wear were excluded.

The study required thirteen measurements of the upper lip which included:

  1. Relaxed upper lip length [Figure 1], measured from the alar base of the nose (Subnasale) to the inferior border of the upper lip (Stomion superius)
  2. Smiling external upper lip length [Figure 2]
  3. Smile index [Figure 3] obtained by dividing the value of inter-commissural width to the inter-labial gap
  4. Mean maxillary central incisor display [Figure 4] measured from the lower border of the upper lip to the incisal edge of the incisor at rest and smiling
  5. Ratio of vermilion border to upper lip length at rest and smiling
  6. Left central incisor clinical crown length
  7. Total lip elevation in subjects during maximum smiling
  8. Internal upper lip length at rest and smiling
  9. Internal upper lip length/external upper lip length ratio at rest and smiling.
Figure 1: Relaxed external upper lip length

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Figure 2: External upper lip length on smiling

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Figure 3: Smile Index

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Figure 4: Left maxillary central incisor display

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All measurements were made directly on the subjects face with the help of a sterilised metal ruler and divider.

The subjects were equally divided into four groups (forty subjects per group) according to age and further sub-divided into two sub-groups according to gender.

Group 1: subjects between ages 11 and 15 years.

Group 2: subjects between ages 16 and 20 years.

Group 3: subjects between ages 21 and 25 years.

Group 4: subjects between ages 26 and 30 years.

Descriptive analysis of all the explanatory and outcome parameters was done using frequency and proportions for categorical variables.


   Results Top


Statistical Package for Social Sciences [SPSS] for Windows Version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses.

Descriptive analysis of all the explanatory and outcome parameters was done using mean and standard deviation for quantitative variables, frequency and proportions for categorical variables.

Inferential Statistics such as analysis of variance (ANOVA) was done followed by post hoc test to determine which groups were significant from others. Levene's test was done to assess equality of variance and t-test for equality of means was done. The level of significance was set at P < 0.05.

Means and standard deviations, derived for all measured variables of the subjects, are given in [Table 1]. Statistically significant sexual dimorphism was apparent in most measured variables. For relaxed external upper lip length measured in males, means obtained for age groups 11–15 years, 16–20 years, 21–25 years and 26–30 years were 16.10 ± 1.86 mm, 19.85 ± 2.47 mm, 21.55 ± 2.30 mm and 24.05 ± 1.93 mm and in females were 15.65 ± 1.42 mm, 19.37 ± 1.99 mm, 20.75 ± 2.17 mm and 21.15 ± 1.9 mm. Significant P value < 0.05 was obtained between age group 1 with the other 3 age groups and age group 2 with age group 4. The mean maxillary central incisor display at rest in age groups 1 and 2, 3 and 4 was decreasing with advancing age.
Table 1: Means and standard deviation of measurement parameters in males and females (excluding smile pattern)

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Means obtained in males were 3.9 ± 1.42 mm, 3.8 ± 1.38 mm, 2.92 ± 1.39 mm and 2.6 ± 1.14 mm respectively and in females were 4.8 ± 1.36 mm, 3.1 ± 1.22 mm, 3.0 ± 0.82 mm and 2.6 ± 1.08 mm. P value < 0.05 was obtained between age group 1 to other 3 age groups in males and age group 1 with age group 2, age group 2 with age group 4 in females.

Smile index increased with increasing age from 5.31 mm to 7.11 mm in males and 5.72 to 6.79 in females. P value for age group 1 with other 3 ages, age group 2 with group 4 in males was < 0.05. Significant results between males and females in age group 2 were obtained with P value < 0.05. High smiles, with exposure of the entire maxillary incisors and a band of gingiva was seen in 30% of males of group 1 decreasing to 0% males in group 4. Similarly, 60% of females of group 1 showed a high smile pattern decreasing to 10% in group 4.

P value < 0.05 was obtained only between males and females of group 4.

Vermilion border constituted 41% of the upper lip length at rest in males and 38% of the length in females. No statistically significant results were obtained between groups with age and P < 0.05 was obtained between males and females of group 2. While smiling, vermilion border formed about 46% of the total external upper lip length in males and 45% in females. These results were statistically insignificant. Central incisor vertical dimension in males was 10.77 mm and in females was 10.34 mm with no significant result obtained with age and gender. No significant results were obtained for the remaining parameters.


   Discussion Top


Facial soft tissue changes achieved during orthodontic therapy are important aspects of gauging overall treatment success. Researchers have studied age-related changes in lip length[8] and maxillary incisor exposure,[9],[10] but to our knowledge, this is the first study which examined smile parameters comprehensively with respect to age and sex in Indian population.

Studies have frequently shown that most dental professionals prefer only the maxillary incisors visible with minimal gingiva when a patient gives a smile on being asked.[11] Minimal gingival exposure on smiling is deemed to be aesthetically appealing by most dentists. They also felt that a natural smile was more reliable in understanding the amount of tooth and gingival show as compared to forced smiles in a clinal setting.

External upper lip length at rest and smiling in males and females

External upper lip length was the vertical measurement from the alar base of the nose (subnasale) to the inferior border of the upper lip (stomion superioris). The results indicated that upper lip length both at rest and smiling increased with increase in subject age.

There was a difference between males and females of the same age group. Males showed increased length of upper lip as compared to that of females in the same age group [Graph 1], [Table 1]. The results of our study were similar to the results obtained in a study by Peck and Peck in 1992,[12] Negi et al. in 2012,[13] Miron et al. in 2012[14] and Sachdeva et al. in 2012.[15] Females showed decreased lip length in all age groups as compared to males.



Mean maxillary central incisor display at rest

There was a decrease in central incisor display with increase in age of the subject and as a result central incisor display at rest was inversely proportional to age of the subject.

Females showed greater incisor display at rest as compared to males within the same age group. This was seen in all the age groups. The results were similar to those of Peck and Peck, Negi et al. and Miron et al.

Mean maxillary central incisor display while smiling

Maxillary central incisor display while smiling was more as compared to that at rest in both sexes and in all age groups. However, central incisor display decreased as age of the subject increased and as a result, central incisor display while smiling was inversely proportional to age of a subject. Females showed greater amounts of incisor display while smiling as compared to males within the same age group at all ages [Graph 2], [Table 1]. These findings were similar to those obtained by Husley and Tjan.[5],[16]

Smile pattern

Smile patterns can be classified as high, medium and low based on the amount of lip elevation and tooth exposure during social smile. If the whole of the clinical crown of the tooth is visible or a band of attached or marginal gingiva is visible, then the smile pattern is characterized as a high smile pattern. If the visibility of a tooth is between 75% to less than 100% of the clinical crown then the smile pattern is characterized as a medium smile pattern and if the clinical crown visibility is less than 75% of its original length then the smile pattern is classified as a low smile pattern. A high smile line is an indicator of a youthful smile and a low smile pattern is an indicator of an old smile. In the present study, smile pattern was shifting towards low pattern as the age of the sample increased in both males and females. Females showed a tendency of having a higher smile pattern as compared to that of males in all age groups.

In age group 1, 30% males showed high smile patterns that reduced to 0% in age Group 3. 60% females showed a high smile pattern in age Group 1 that reduced to only 10% of females having high smile pattern [Graph 6], [Graph 7].



Central incisor clinical crown height

Central incisor crown height in males was slightly more than that of the females in all age groups and maximum values were seen in males of Group 4 with mean 11.02 mm and females of Group 3 with 10.6 mm [Graph 3]. Statistically significant results were not obtained for this parameter.

The results obtained from this study were slightly less than those in the study by Miron et al.[14] as age related changes in the upper lip dimensions were taken into consideration in this study. For maximum aesthetic value, the anatomic crown should be fully exposed taking the ratio of clinical to anatomic crown heights to 1:1.[17]

Total lip elevation in subjects during maximum smiling

Total lip elevation is the amount of lip elevated when a subject shows a social smile. It is calculated when the incisor exposure during rest is subtracted from incisor exposure during social smiling.

In the present study, lip elevation decreased with increase in age of the subjects in both sexes [Graph 4], [Table 1]. This indicated that there was some drooping effect in the muscles of the upper lip. In males, this effect was more prominent and seen mostly after 25 years of age. The effect of age on upper lip elevation is more in males than in females.

Smile index

Smile index of a subject can be obtained by dividing the inter-commissural width of a person to inter-labial gap. There is an increase in smile index with age from 5.31 in males of group 1 to 7.11 in group 4 [Table 1], [Graph 5]. This shows that the smile becomes increasingly more horizontal with increase in age. Major change was observed between males of group 3 to males of group 4. In females, smile index increased from 5.72 in group 1 to 6.79 in group 4. In females with increasing age, the smile turns out more horizontal.

Major changes were seen between group 3 and group 4. Between males and females, statistically significant results were observed in group 2. The results were slightly different from the results obtained by Durgekar et al.,[18] as the sample age taken in that study was between 18 and 25 years. Age groups 11–15 years and 26–30 years were not included.


   Conclusion Top


  1. Data from this study clearly indicates age and sexual dimorphism in upper lip length, maxillary incisor display, upper labial vestibule insertion and smile index. High smile patterns are more common among females and low smile patterns are more common among males.
  2. Males and females show subtle differences in certain lip parameters at various ages. This should be kept in mind while planning treatment.
  3. Lip parameters for Indian population divided for gender and ages, as obtained in this study, will be very useful for orthodontists and dentists in order to obtain ideal anterior aesthetics after treatment.


Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Key Messages

With a paradigm shift to soft tissues in decision making during various stages of orthodontic treatment, greater importance is being given to aesthetics. Data from the study clearly indicates the relationship of age and sexual dimorphism in upper lip length, maxillary incisor display, upper labial vestibule insertion and smile index.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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2.
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Peck S, Peck L, Kataja M. The gingival smile line. Angle Orthod 1992;62:91-100.  Back to cited text no. 8
    
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Rosenblatt A, Simon Z. Lip repositioning for reduction of excessive gingival display: A clinical report. Int J Periodontics Restorative Dent 2006;26:433-7.  Back to cited text no. 11
    
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Negi N, Verma S, Negi KS, Kaundal JR, Sood S. Soft tissue cephalometric norms for north Indian Mongoloids. Orthod Waves 2019;71:85–9.  Back to cited text no. 13
    
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Miron H. Upper lip changes and gingival exposure on smiling: Vertical dimension analysis. Am J Orthod Dentofacial Orthop 2012;141:87-93.  Back to cited text no. 14
    
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Sachdeva K Esthetics and smile characteristics at rest and during smiling. J Ind Orthod Soc 2012;46:17-25.  Back to cited text no. 15
    
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Hulsey CM. An esthetic evaluation of lip-teeth relationships present in the smile. Am J Orthod 1970;57:132-44.  Back to cited text no. 16
    
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Thomas C. Waldrop Gummy smiles: The challenge of gingival excess: Prevalence and guidelines for clinical management. Semin Orthod 2008;14:260-71.  Back to cited text no. 17
    
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Durgekar SG. The ideal smile and its orthodontic implications. World J Orthod 2010;11:211-20.  Back to cited text no. 18
    

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Correspondence Address:
Dr. Prasad Chitra
Department of Orthodontics and Dentofacial Orthopedics, Army College of Dental Sciences, Jai Jawahar Nagar, Chennapur, CRPF Road, Secunderabad, Telangana - 500 087
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_637_18

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