SRM Journal of Research in Dental Sciences

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 10  |  Issue : 4  |  Page : 209--213

Mentolabial sulcus and malocclusion: Facial esthetics in ethnic Tamil population


MS Brindha, R Ramya, R Bharanidharan, Divyalakshmi Govindaram, K Rajkumar 
 Department of Oral and Maxillofacial Pathology and Microbiology, SRM Dental College, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Divyalakshmi Govindaram
Department of Oral and Maxillofacial Pathology and Microbiology, SRM Dental College, Ramapuram, Chennai, Tamil Nadu
India

Abstract

Aim: The aim of this study was to evaluate the soft-tissue parameter that is depth and angle of mentolabial sulcus and to correlate this parameter with type of malocclusion present in an ethnic Tamilian population. Objective: The objective of the study was to evaluate the depth and angle of the mentolabial sulcus, to determine the type of malocclusion, and to correlate the soft-tissue parameter and malocclusion. Materials and Methods: This study was conducted in 260 university students (65 males and 95 females) between April and September 2018. Photographs of all the students were taken using a digital camera. Mentolabial sulcus depth and angles were measured from the lateral photographs using an angle instrument along with the molar and canine relation. The type of mentolabial sulcus was also taken into account. The data were analyzed using the SPSS software version 22. The comparison of sulcus between males and females was performed using two-sample t-test at 95% confidence interval. Results: The mean mentolabial sulcus angle in the Tamilian population was 117.18° ± 9.24° (males: 118.19° ± 12.28° and females: 116.19° ± 12.28°). There was no statistically significant difference of sulcus angle between males and females (P = 0.078). 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. Conclusion: The mean mentolabial sulcus angle in the Tamilian population was 117.18° ± 9.24°, in males was 118.19° ± 12.28°, and in females was 116.19° ± 12.28°. 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 the Tamilian population.



How to cite this article:
Brindha M S, Ramya R, Bharanidharan R, Govindaram D, Rajkumar K. Mentolabial sulcus and malocclusion: Facial esthetics in ethnic Tamil population.SRM J Res Dent Sci 2019;10:209-213


How to cite this URL:
Brindha M S, Ramya R, Bharanidharan R, Govindaram D, Rajkumar K. Mentolabial sulcus and malocclusion: Facial esthetics in ethnic Tamil population. SRM J Res Dent Sci [serial online] 2019 [cited 2022 Sep 25 ];10:209-213
Available from: https://www.srmjrds.in/text.asp?2019/10/4/209/276374


Full Text

 Introduction



The assessment of facial soft tissue has developed as a crucial component of assessing the patient for esthetic, cosmetic dentistry, and reconstructive surgeries. Facial soft-tissue profile can correlated to the type of malocclusion present in the patient, thus determining the skeletal and soft-tissue facial profile. Previous literature suggests that the soft tissues play as a significant factor in defining a patient's final facial profile.[1],[2],[3],[4] Numerous investigations have highlighted the significance of the soft tissue which behaves independently from the underlying skeleton in determining the facial esthetics.[5]

Mentolabial sulcus is also known as the labiomental fold. It is one among the most imperative esthetic parameters taken into account of the lower face, thus determining the soft-tissue profile of an individual.[6],[7],[8] In frontal view, it forms the visible indentation responsible for the separation of the lower lip from the chin is known as the mentolabial groove or crease. It is evident and forms the transition from the lower lip to the soft-tissue chin in the lateral view.[9] 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. The mentolabial angle is formed as the angle between the line joining the labrale inferius and the depth of the sulcus to the pogonion point. Class III skeletal profile individuals exhibit an obtuse mentolabial sulcus angle, whereas those with Class II skeletal profile have an acute one.[10]

Variations in the mentolabial sulcus, according to ethnicity and races of the people, have been reported in previous literatures. Scavone stated that every ethnic group exhibited specific dentofacial characteristics in each ethnic group. Different ethnic groups may have different skeletal base pattern and facial features thus may reflect on the variations in the soft-tissue profile of the face.[11] The mentolabial sulcus depth and angle has not been studied in the Tamilian population till date. Hence, the aim of the study was to evaluate and correlate the depth and the angle of the mentolabial sulcus and the type of malocclusion prevalent in the ethnic Tamilian population included in the study.

 Materials and Methods



The present observational study was carried out on 260 participants to correlate the depth and angle of the mentolabial sulcus and the type of malocclusion in the Tamilian population. Each individual under the study was subjected to the evaluation of the molar and canine relation to determine the Angle's type of malocclusion. Further, the participants were evaluated for the type, depth, and the angle of the mentolabial sulcus. Ethical approval was obtained from the Institutional Review Committee, and the participants were requested to sign informed consent before obtaining the information.

The mentolabial sulcus depth and angle were measured using digital photographs (Fujifilm Co., Tokyo, Japan). A line was drawn from the landmarks, that is, labrale inferius to pogonion and the deepest point in the sulcus that is submentale was accounted for the depth of the mentolabial sulcus. The angle between the lines drawn from labrale inferius to submentale and from this point to the pogonion was measured using an angle instrument [Figure 1] and [Figure 2]. The type of mentolabial sulcus was also evaluated based on the classification of deep, average, and shallow.{Figure 1}{Figure 2}

Standardization of the protocol followed

The right lateral position of the participants was recorded through the digital photographs. The distance between the participant and the camera was 1.5 m. The distance between the participant and the background was 0.5 m.

Inclusion criteria

The inclusion criteria were as follows:

Males and females of 18–25 years of ageA full complement of permanent dentition present (excluding the third molar)Participants with past three generations living in Tamil Nadu and with mother tongue as the Tamil language.

Exclusion criteria

The exclusion criteria were as follows:

Participants with a history of orthodontic treatment or orthognathic surgeryPrevious history of trauma to maxillofacial structuresCongenital deformities such as cleft lip and palateCompromised periodontal condition.

The data were analyzed using the statistical software package SPSS (IBM Corp., Version 22.0, Armonk, NY, USA). The comparison of sulcus between males and females was performed using two-sample t-test at a 95% confidence interval.

 Results



Two hundred and sixty participants were included in the study with 157 females (60.3%) and 103 males (39.6%) [Table 1]. The participants were assessed for the type of malocclusion, and the groups were segregated as follows:

Group I: Class 1Group II: Bimaxillary protrusionGroup III: Class 2 div 1Group IV: Class 2 div 2Group V: Class 3.{Table 1}

Independently, each of the groups was statistically evaluated and correlated with the mentolabial depth and angle [Table 2].{Table 2}

The mean mentolabial sulcular depth and angle in each of the groups are summarized in [Table 2]. The mean mentolabial sulcus angle in participants was 112.50° ± 12.28° in Group I – Class 1 malocclusion. The mean mentolabial sulcus angle in participants was 132.58° ± 9.48° in Group II – bimaxillary protrusion. The mean mentolabial sulcus angle in participants was 128.60° ± 9.28° in Group III – Class 2 div 1 malocclusion. The mean mentolabial sulcus angle in participants was 122.60° ± 9.20° in Group IV – Class 2 div 2 malocclusion. The mean mentolabial sulcus angle in participants was 103.67 ± 8.49 in Group V – Class 3 malocclusion.

[Table 3] and [Figure 3] represents the type of mentolabial angle classification applied to the type of malocclusion.{Table 3}{Figure 3}

The mean sulcus angle in males was 118.19° ± 12.28° and in females was 116.19° ± 12.28. The sulcus angle was no statistically significant difference between males and females (P = 0.078, α =0.05) [Table 4].{Table 4}

 Discussion



Facial esthetics is the principal factor that determines a treatment protocol in orthodontics. The mentolabial sulcus forms an important factor in terms of facial cosmetics of the lower face. Zide and Boutros have heretofore termed a critical diagnostic point on the decision of the reduction levels and extent in genioplasty in patients with horizontal macrogenia: the upper component of the mentolabial angle that is inclination of the line from the lower lip to the mentolabial groove.[12]

Type of malocclusion is one among the gamut of factors causing changes to the soft-tissue profile of the face. Nasolabial and mentolabial angles are two important guides involved in orthognathic surgery. Any eccentricity or deviation of these angles from the norm should be considered in the presurgical assessment in orthognathic surgeries. McCollum and Evans had emphasized on the importance to predict the occlusal and skeletal relationships along with the soft-tissue outcome to customize a particular treatment protocol. Thus, restoring these angles to its norm becomes an important objective of treatment for the patient. Hence, it becomes essential to attain knowledge on the norms of these angles in a population to produce a more accurate and social-acceptable outcome of the surgery.[13]

This study aimed at correlating the type of malocclusion and mentolabial sulcus depth and angle to emphasize on the importance of these parameters in the classification and in turn the application of a particular treatment protocol which would aim at improving the facial esthetics that is determined by skeletal, dental, and soft-tissue parameters. The students who participated in this study were considered a sample population of an ethnic Tamil populace. In this study, average sulcus type (38.12%) was the most predominant type of sulcus associated with Class 1 malocclusion predominantly. It was found that the mean sulcus angle in study participants was 117.19° ± 12.28°. Naini et al. identified the most attractive angular range for mentolabial angle with a range of 107°–118°. 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.[14]

The sample participants were classified into five groups based on the molar and canine relation. The type of mentolabial sulcus was classified as average, shallow, and deep. Class 1 malocclusion showed the highest frequency of values falling under the above mentioned range as well as correlating with the type mentolabial sulcus that is the average type which is predominant in this group. The group with bimaxillary protrusion showed shallow type of mentolabial sulcus whereas the gropps with Class 2 and Class 3 malocclusion showed a deep angle and deep type of sulcus. There were no statistically significant differences in between the different groups. Similarly, statistically significant differences were not observed between males and females. Mentolabial sulcus along with other facial measurements such as face height and face width of the 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 the esthetic outcome in the lower face and restorative planning of lower denture for optimizing the labial fullness.[15] This study may also be applied in other populations to find the most common type of mentolabial sulcus.

 Conclusion



The mean mentolabial sulcus angle in the Tamilian student population was 117.19° ± 12.28°. There was no statistically significant difference of sulcus angle between the males and females. The mentolabial sulcus is classified as average, deep, and shallow in males and females. The average type of sulcus was the most predominant type found in Class I malocclusion which was the most prevalent type in the above study population. Further, a large sample population must be evaluated to be able to generalize the results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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