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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 13  |  Issue : 1  |  Page : 16-19

Mentolabial sulcus: An esthetic-based classification


1 Department of Dentistry, Kathmandu University School of Medical Sciences, Dhulikhel, Kavre, Nepal
2 Department of Dentistry, National Institute of Neurological and Allied Sciences, Kathmandu, Nepal
3 Department of Community Dentistry, Faculty of Dentistry, Western University, Lam Kuk Ka, Pathumthani 12150, Thailand

Date of Web Publication10-Sep-2018

Correspondence Address:
Dr. Dinesh Rokaya
Department of Dentistry, Kathmandu University School of Medical Sciences, Dhulikhel, Kavre
Nepal
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdmimsu.jdmimsu_80_17

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  Abstract 


Objectives: The objectives of this study were to study the mentolabial sulcus in Nepalese, to compare the sulcus between male and female, and to classify the sulcus according to the angle. Materials and Methods: This study was conducted in 160 university students (65 males and 95 females) between April and September 2016. Photographs of all the students were taken using a digital camera. Mentolabial sulcus angles were measured from the lateral photographs using an angle instrument. The data were analyzed using SPSS 22. The comparison of sulcus between male and female was done using two-sample t-test at 95% confidence interval. Results: The mean mentolabial sulcus angle in Nepalese was 118.19° ±12.28° (male: 119.43° ± 9.99° and female: 117.61° ± 13.23°). There was no statistically significant difference of sulcus angle between males and females (P = 0.098). The sulcus was classified as deep, average, and shallow in males and females. In total students, the average was more predominant followed by deep and shallow. Conclusions: The mean mentolabial sulcus angle in Nepalese was 118.19° ± 12.28°, in male was 119.43° ± 9.99°, and in female was 117.61° ± 13.23°. The sulcus was classified as deep, average, and shallow. There was no statistically significant difference of sulcus angle between males and females. The average type of sulcus was more predominant in Nepalese.

Keywords: Asian, esthetics, face, mentolabial sulcus, Nepalese


How to cite this article:
Rokaya D, Bhattarai BP, Suttagul K, Kafle D, Humagain M. Mentolabial sulcus: An esthetic-based classification. J Datta Meghe Inst Med Sci Univ 2018;13:16-9

How to cite this URL:
Rokaya D, Bhattarai BP, Suttagul K, Kafle D, Humagain M. Mentolabial sulcus: An esthetic-based classification. J Datta Meghe Inst Med Sci Univ [serial online] 2018 [cited 2018 Sep 26];13:16-9. Available from: http://www.journaldmims.com/text.asp?2018/13/1/16/240906




  Introduction Top


The evaluation of facial soft tissue has become an essential component of patient assessment for facial esthetic, cosmetic dentistry, and reconstructive surgeries.[1],[2] Facial soft-tissue measurements and analysis can be accomplished using facial photography, lateral cephalometry, and three-dimensional radiography.[3],[4]

Mentolabial sulcus (also known as labiomental fold) is one of the most important esthetic parameters of the lower face.[5],[6],[7] In frontal view, the visible indentation responsible for the separation of the lower lip from the chin is known as the mentolabial groove or crease.[5] In the lateral view, it is evident forming the transition from the lower lip to the soft-tissue chin.[8] Within the sulcus angle, an inclination of the lower lip in relation to the true horizontal line through sublabiale is known as the upper component, whereas the inclination of the soft-tissue chin to the true horizontal line through sublabiale is known as the lower component.[9] Naini et al.[10] mentioned that a mentolabial angle of 107°–118° (male: 115°–145° and female: 120°–130°) is considered as the most attractive although angle up to 140° is deemed acceptable. Individuals with Class III skeletal profile exhibit an obtuse mentolabial sulcus angle, whereas those with Class II skeletal profile have an acute one.[11],[12]

Mentolabial sulcus varies according to ethnicity and races of the people. However, the mentolabial sulcus has not been studied in Nepalese and in Asian population till date. Therefore, this study on the sulcus will be a guide for Nepalese population and a preliminary study for the Asian population.


  Materials and Methods Top


The objectives of this study were to study the mentolabial sulcus in Nepalese population, to compare the sulcus between male and female, and to classify the sulcus according to the angle. This cross-sectional study was conducted in a total of 160 university students (65 males and 95 females) between April 2016 and September 2016. Students were selected using following criteria: (1) age of the participants: 18–30 years, both males and females; (2) not treated with any facial surgery involving the lower third of the face; and (3) obvious problems that could disfigure of the face. The details of the study participants are provided in [Table 1]. Ethical approval was obtained from the Institutional Review Committee, and the participants were requested to sign informed consent prior and assured that confidentiality of all information was maintained.
Table 1: Details of the study participants in the study

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Photographs (frontal and lateral) of all the students were taken using a digital camera (Fujifilm FinePix HS30, Fujifilm Co., Japan) at a distance of 1.6 m from the camera and 0.6 m from the background [Figure 1] and [Figure 2]. Mentolabial sulcus angle was measured from the lateral photograph using an angle instrument (AngleRuler, ADA Instrument Co., Ltd, Hong Kong) [Figure 3]. The data analysis was done using statistical software packageb SPSS (IBM Corp., Version 22.0, Armonk, NY, USA) for Windows. Descriptive statistics were calculated. The comparison of sulcus between male and female was done using two-sample t-test at 95% confidence interval.
Figure 1: Mentolabial sulcus angle

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Figure 2: Experimental setup for the photograph of the subjects. m: Meter

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Figure 3: Measurement of mentolabial sulcus angle

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  Results Top


The mean mentolabial sulcus angle in Nepalese students was 118.19° ± 12.28° (lower bound: 116.21° and upper bound: 120.17°) [Table 2]. The mean sulcus angle in male was 119.43° ± 9.99° (lower bound: 115.01° and upper bound: 120.21°) and in female was 117.61° ± 13.23° (lower bound: 116.53° and upper bound: 122.33°) [Table 3]. Box plot representation of mentolabial sulcus angle in males and females is shown in [Figure 4]. The sulcus angle was no statistically significant difference between male and female (P = 0.098, α = 0.05).
Table 2: Mentolabial sulcus angle in Nepalese participants

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Table 3: Comparison of mentolabial sulcus angle between males and females

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Figure 4: Box plot representation of mentolabial sulcus angle in males and females. F: Female, m: Male

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The mentolabial sulcus was classified as Type I: deep, Type II: average, and Type: shallow in males and females [Table 4] [Figure 5], [Figure 6], [Figure 7]. Deep sulcus was seen in 40% of males and 32.63% of females. Average sulcus was seen in 41.53% of males and 52.63% of females. Shallow sulcus was seen in 18.46% of males and 14.73% of females. In total students, the average was more predominant (35.62% deep, 48.12% average, and 16.25% shallow). The average type of mentolabial sulcus was more predominant in Nepalese students.
Table 4: Classification of mentolabial sulcus in male and female according to the extent of the sulcus angle

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Figure 5: Examples of deep type of mentolabial sulcus in males (a) and females (b)

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Figure 6: Examples of average type of mentolabial sulcus in males (a) and females (b)

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Figure 7: Examples of shallow type of mentolabial sulcus in males (a) and females (b)

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  Discussion Top


Mentolabial sulcus is important in terms of facial cosmetics of the lower face. Zide and Boutros have described a critical diagnostic point when deciding on the extent of reduction genioplasty in patients with horizontal macrogenia: the upper component of the mentolabial angle which is the inclination of the line from the lower lip to the mentolabial groove.[13]

The students who participated in this study were the students from different parts of the country. In this study, average sulcus type (48.12%) was the most predominant type of sulcus.

It was found that the mean sulcus angle in Nepalese students was 118.19°. Naini et al.[10] found a mentolabial angle of 107°–118° and considered this range as the most attractive among others. This result falls under category of the average type of sulcus in our study. They concluded that mentolabial angle above or below this range (107°–118°) is perceived as unattractive, whereas a deep angle (84°) or an almost flat angle (162°) is the least attractive. Therefore, this study which measured these facial soft-tissue angles is quite contextual in the contemporary period so that an overview of the normative values could be estimated.[10]

Mentolabial sulcus along with other facial measurements such as face height and face width of eyes, nose, and mouth may also be used to classify a face as attractive or unattractive. The results of mentolabial sulcus from this study might be useful as cephalometric norms in the facial cosmetic surgery for planning esthetic outcome in the lower face and restorative planning of lower denture for optimizing the labial fullness.[14] This study may also be applied in other Asian population to find the most common type of mentolabial sulcus in the Asian population.


  Conclusions Top


The mean mentolabial sulcus angle in Nepalese students was 118.19° ± 12.28° (male: 119.43° ± 9.99° and female: 117.61° ± 13.23°). There was no statistically significant difference of sulcus angle between the male and the female. The mentolabial sulcus is classified as Type I: deep, Type II: average, and Type: shallow in males and females. The average type of sulcus was the most predominant type in the Nepalese students.

Acknowledgments

We thank all the participants who participated in this study. We are grateful to Kathmandu University School of Medical Sciences for the financial support for this study. We would like to thank the staff of Kathmandu University School of Medical Sciences for their technical assistance in conducting this research.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given his their consent for 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.

Financial support and sponsorship

We are grateful to Kathmandu University School of Medical Sciences for the financial support for this study.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Proffit WR, Fields HW Jr., Sarver DM. Contemporary Orthodontics. 4th ed. St. Louis: Mosby; 2007.  Back to cited text no. 1
    
2.
Papel ID. Facial Plastic and Reconstructive Surgery. 2nd ed. New York: Thieme Medical Publishers; 2002.  Back to cited text no. 2
    
3.
Fortes HN, Guimarães TC, Belo IM, da Matta EN. Photometric analysis of esthetically pleasant and unpleasant facial profile. Dental Press J Orthod 2014;19:66-75.  Back to cited text no. 3
    
4.
Incrapera AK, Kau CH, English JD, McGrory K, Sarver DM. Soft tissue images from cephalograms compared with those from a 3D surface acquisition system. Angle Orthod 2010;80:58-64.  Back to cited text no. 4
    
5.
Naini FB, Gill DS. Facial aesthetics: 1. Concepts and canons. Dent Update 2008;35:102-4, 106-7.  Back to cited text no. 5
    
6.
Lee JJ, Ridgway JM. Facial aesthetics: Concepts and clinical diagnosis. Arch Facial Plast Surg 2012;14:372.  Back to cited text no. 6
    
7.
Lee EI. Aesthetic alteration of the chin. Semin Plast Surg 2013;27:155-60.  Back to cited text no. 7
    
8.
Rosen HM. Aesthetic refinements in genioplasty: The role of the labiomental fold. Plast Reconstr Surg 1991;88:760-7.  Back to cited text no. 8
    
9.
Naini FB. Facial Aesthetics: Concepts and Clinical Diagnosis. 1st ed. New Jersey: Blackwell Publishing; 2011.  Back to cited text no. 9
    
10.
Naini FB, Cobourne MT, Garagiola U, McDonald F, Wertheim D. Mentolabial angle and aesthetics: A quantitative investigation of idealized and normative values. Maxillofac Plast Reconstr Surg 2017;39:4.  Back to cited text no. 10
    
11.
Reyneke JP, Ferretti C. Clinical assessment of the face. Semin Orthod 2012:18:172-86.  Back to cited text no. 11
    
12.
Fernández-Riveiro P, Smyth-Chamosa E, Suárez-Quintanilla D, Suárez-Cunqueiro M. Angular photogrammetric analysis of the soft tissue facial profile. Eur J Orthod 2003;25:393-9.  Back to cited text no. 12
    
13.
Zide BM, Boutros S. Chin surgery III: Revelations. Plast Reconstr Surg 2003;111:1542-50.  Back to cited text no. 13
    
14.
Albarakati SF, Baidas LF. Orthognathic surgical norms for a sample of Saudi adults: Hard tissue measurements. Saudi Dent J 2010;22:133-9.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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