Open Access Original
Article
DOI: 10.7759/cureus.59150
Comparison of Soft Tissue Chin Thickness in
Adult Patients With Various Mandibular
Divergence Patterns
Review began 04/17/2024
Review ended 04/23/2024
Muhammad Noman 1 , Gulsana Hashmi 2, Munawar Manzoor Ali 3, Usman Yousaf 2 , Mazhar Hussain 1,
Rida Mujeeb 4
Published 04/27/2024
© Copyright 2024
Noman et al. This is an open access article
distributed under the terms of the Creative
Commons Attribution License CC-BY 4.0.,
which permits unrestricted use, distribution,
and reproduction in any medium, provided
the original author and source are credited.
1. Orthodontics and Dentofacial Orthopaedics, Sharif Medical and Dental College, Lahore, PAK 2. Orthodontics and
Dentofacial Orthopaedics, University College of Medicine and Dentistry, University of Lahore, Lahore, PAK 3.
Orthodontics and Dentofacial Orthopaedics, Azra Naheed Dental College, Superior University, Lahore, PAK 4.
Operative Dentistry and Endodontics, Fatima Memorial Hospital College of Medicine and Dentistry, Lahore, PAK
Corresponding author: Muhammad Noman, knomankhan@gmail.com
Abstract
Objective
This study aimed to compare the soft tissue chin (STC) thickness at different levels in patients presenting for
orthodontic treatment with different vertical facial types.
Materials and methods
This comparative cross-sectional study was conducted at Sharif Medical & Dental College, Lahore, Pakistan,
on 195 subjects. Patients presenting for orthodontic treatment, both genders, aged from 18 to 32 years, and
Pakistani nationals were included. Patients with any craniofacial deformity, syndrome, cleft lip and palate,
previous orthodontic or orthognathic treatment, and multiple missing teeth and prostheses in edentulous
areas were excluded. Vertical facial patterns and STC thickness were recorded from pre-treatment lateral
cephalograms. One-way analysis of variance (ANOVA) was applied to compare STC among various vertical
facial patterns. Post-hoc analysis was done using the Tukey test.
Results
There were 126 females (64.62%) and 69 males (35.38%). The mean age was 21.66 ± 3.44 years. All three soft
tissue chin thickness distances significantly differed among vertical facial patterns (p<0.001). Multiple
comparisons show that the distance between soft and hard tissue pogonion was insignificant between low
and normal angle facial heights (p=0.5). Similarly, no significant difference was observed for the distance
between soft and hard tissue menton in low and normal angle subjects (p=0.4). The rest of the multiple
comparisons were statistically significant (p<0.05).
Conclusion
The STC thickness is significantly associated with vertical facial divergence. While planning orthognathic
surgery or genioplasty of the mandible, due consideration should be given to vertical divergence of the face
to avoid unwanted facial changes.
Categories: Dentistry
Keywords: cephalometric study, orthognathic hypo divergent, hyper divergent, soft tissue chin, mandibular
divergence
Introduction
Soft tissue chin (STC) thickness and morphology are significant for orthodontists and plastic surgeons while
providing patient care [1]. The aim of orthodontic treatment is not limited to dental and hard tissue
correction. However, the final aim of this treatment modality is to position teeth and skeletal tissue to
achieve a normal and balanced soft tissue profile [2]. Treatment success and failure in orthodontics directly
correlate with soft tissue balance [3].
Five main soft tissue entities make the facial profile [4]. These components are the submental-cervical
region, chin, lips, nose, and forehead. The interplay among these five components creates an attractive or
abnormal profile [5].
The lower face is framed by the nose above and the chin below, which defines the aesthetics. Most of the
time, the rhinoplasty is carried out in coordination with chin morphology and vice versa. A case with lip
protrusion can usually occur if the chin is prominent. A non-extraction treatment is sometimes justified in
How to cite this article
Noman M, Hashmi G, Manzoor Ali M, et al. (April 27, 2024) Comparison of Soft Tissue Chin Thickness in Adult Patients With Various Mandibular
Divergence Patterns. Cureus 16(4): e59150. DOI 10.7759/cureus.59150
patients with good chin morphology [6,7].
Vertical face growth is the last to end among all dimensions. The individuals can be divided into three
vertical facial patterns (hyperdivergent, hypodivergent, and normodivergent). Soft tissue growth correlates
with underlying hard tissue growth [8]. Patients with long faces have weak and thin soft tissue
morphology while cases with deep skeletal bites have strong and thick soft tissues [9,10].
A study on 195 lateral cephalograms reported that STC thickness values were most diminutive in
hyperdivergent (7.47 ± 2.42 mm) and thickest in hypodivergent patients (11.78 ± 3.37 mm) [11]. The
difference was statistically significant.
This study aims to measure and compare the thickness of the chin at different levels in various mandibular
divergences. No previous data for our population can be found on soft tissue chin thickness measurements.
This study will significantly help understand the soft tissue morphology of chin thickness and quantify visual
treatment objectives in treatment planning.
Materials And Methods
This cross-sectional comparative study was conducted at the Department of Orthodontics, Sharif Medical &
Dental College, Raiwind Road, Jati Umrah, Lahore, Pakistan from 1 January to 30 July 2022 on 195
cephalograms by non-probability consecutive sampling. A sample size of 195 cases was calculated with a
95% confidence interval and 6% margin of error. Ethical approval (Reference # 319-AD/PG/R/SMDC) was
obtained from the Ethical Committee of Sharif Medical and Dental College. After an in-depth explanation of
the study, informed consent was obtained from each participant.
Patients presenting for orthodontic treatment, of both genders, with ages ranging from 18 to 32 years, and
Pakistani nationals were included. Patients with craniofacial deformity or syndrome, cleft lip and palate,
previous orthodontic or orthognathic treatment, multiple missing teeth, and prostheses were excluded.
Age, gender, and cephalometric parameters were recorded from each participant. Standardized pretreatment lateral cephalograms were taken with the “SoreDexCarnex-D Ceph” machine in a natural head
position with lips relaxed. The lateral cephalogram of each subject was traced manually by a single operator
in a standardized manner to avoid errors due to inter-operator variations. Standard 0.003 inch acetate
tracing paper with a 0.3 mm mechanical pencil was used. The vertical facial divergence was calculated based
on angular measurements of anterior cranial base length (SN) and mandibular plane (MP) as follows:
Horizontal growth pattern (hypodivergent): Low angle SN-MP < 27°
Normal growth pattern: Normal angle SN-MP (32° ± 5°)
Vertical growth pattern (Hyperdivergent): High angle > 37°
Soft tissue chin (STC) thickness was measured at three different levels:
Pog-Pog': Linear distance of bony pogonion (Pog) and its horizontal projection soft tissue pogonion (Pog')
Gn-Gn': Distance between bony gnathion (Gn) and its horizontal projection soft tissue gnathion (Gn')
Me-Me': Distance between bony menton (Me) and soft tissue menton (Me') (Figure 1) [11]
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FIGURE 1: Radiographic anatomic landmarks of the mandible and chin
used for measurement
To the left: Mandibular plane (menton-gonion) and sella-nasion plane angle. To the right: Measurements of skin
thickness at the chin were evaluated: hard tissue pogonion and the distance to its horizontal projection on the soft
tissue (Pog-Pog’), distance from hard tissue gnathion to soft tissue gnathion (Gn-Gn’), and the distance from hard
tissue menton to its vertical projection on the soft tissue (Me-Me’)
Source: Macari AT, Hanna AE. Comparisons of soft tissue chin thickness in adult patients with various mandibular
divergence patterns. The Angle Orthodontist. 2014. [11] (Open Access)
Descriptive statistics were calculated for numerical data in terms of mean with SD and for categorical
variables in terms of frequencies with percentages. STC parameters were compared among various facial
vertical divergences (Normal, Low, High angle) using a one-way analysis of variance (ANOVA) test, and post
hoc analysis was carried out using the Tukey test. Analysis was stratified among genders for controlling
confounders. The level of significance was kept at p < 0.05.
Results
The mean age was 21.66 ± 3.44 years, with the rest of the demographics shown in Table 1. The mean vertical
angle was 32.09 ± 6.220. The mean distance from soft tissue (pog’) to hard tissue pogonion (Pog) was 11.14 ±
2.76 mm. The rest of the details are given in Table 2. The most common vertical facial pattern was normal
(n=104, 53.33%), followed by high angle (n=50, 25.64%), and the least was low angle (n=41, 21.035).
Characteristic
N (%)
Female
126 (64.62)
Male
69 (35.38)
18 – 22 years
141 (72.3)
23 – 27 years
33 (16.9)
28 – 32 years
21 (10.8)
Gender
Age group
TABLE 1: Distribution of gender and age group
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Characteristic
Mean ± SD
SN-MP angle (degree)
32.09 ± 6.22
Pog to pog’(mm)
11.14 ± 2.76
Gn to Gn’(mm)
7.75 ± 2.13
Me to Me’(mm)
7.19 ± 1.76
TABLE 2: Mean vertical angle and cephalometric soft tissue chin thickness
Pogonion (Pog); Gnathion (Gn); Menton (Me); Sella Nasion to Mandibular Plane (SN-MP)
All three STC thickness distances significantly differed among vertical facial patterns (p<0.001). Multiple
comparisons show that the distance between soft and hard tissue Pog was insignificant between low and
normal angles (p=0.5). Similarly, no significant difference was observed for the distance between soft tissue
and hard tissue menton between low and normal angles (p=0.4). The rest of the multiple comparisons were
statistically significant (p<0.05) (Table 3).
Post-hoc analysis (P-value)(b)
Mean ± SD
P-value(a)
Variable (mm)
High, N = 50
Low, N = 41
Normal, N = 104
High vs. Low
High vs. Normal
Low vs. Normal
Pog to pog’
9.40 ± 2.87
11.50 ± 2.26
11.83±2.53
<0.001 *
<0.001
<0.001
0.5
Gn to Gn’
6.72 ± 1.26
8.72 ± 2.61
7.86 ± 2.06
<0.001 *
<0.001
0.001
0.022
Me to Me’
6.28 ± 1.25
7.32 ± 1.71
7.58 ± 1.85
<0.001 *
0.004
<0.001
0.4
TABLE 3: Comparison and post-hoc analysis of soft tissue chin thickness among various vertical
facial patterns of all participants
High: Hyperdivergent > 37°, Normal: Normal angle (32° ± 5°), Low: Hypodivergent < 27°
Note: (*): Statistically significant (p-value<0.000)
(a) One-way ANOVA (comparison of STC parameters among various facial vertical divergences (Normal, Low, High)
(b)Post-hoc analysis: Difference between groups through the Tukey test (Difference of mean value of High vs. Low)
ANOVA: analysis of variance
In males, similar results were found in the overall study, except that no statistical difference was found for
soft tissue chin thickness parameters low versus normal angle (p>0.05) (Table 4). Among females, the
difference was statistically significant except for Gn-Gn’ between high and normal angle (p=0.13), Pog-Pog’
between low and normal angle (p=0.7), and Me-Me’ between low and normal angle (p=0.5) (Table 5).
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Post-hoc analysis(b) (Difference of mean values between high, low, and normal)
P-Value (a)
Variable (mm)
High, N = 16
Low, N = 11
Normal, N = 42
High vs. Low
High vs. Normal
Low vs. Normal
Pog to pog’
9.09 ± 2.44
11.82 ± 2.48
12.18 ± 2.52
<0.001*
0.007
<0.001
0.7
Gn to Gn’
6.12 ± 0.79
8.8 ± 2.27
8.14 ± 2.25
<0.001*
0.001
0.001
0.3
Me to Me’
6.25 ± 1.05
7.73 ± 2.10
7.76 ± 1.74
<0.001*
0.027
0.003
>0.9
TABLE 4: Comparison and post-hoc analysis of soft tissue chin thickness among various vertical
facial patterns in males
High: Hyperdivergent > 37°, Normal: Normal angle (32° ± 5°), Low: Hyperdivergent < 27°
Note: (*): Statistically significant (p-value<0.000)
(a) One-way ANOVA (comparison of STC parameters among various facial vertical divergences (Normal, Low, High angle)
(b) Post-hoc analysis: Difference between groups through the Tukey test
ANOVA: analysis of variance
Post-hoc analysis(b) (Difference of mean values between high, low, and normal)
Variable (mm)
High, N = 34
Low, N = 30
Normal, N = 62
P-value(a)
High vs. Low
High vs. Normal
Low vs. Normal
Pog-Pog’
9.54 ± 3.07
11.38 ± 2.20
11.60 ± 2.53
<0.001*
0.006
<0.001
0.7
Gn-Gn’
7.00 ± 1.35
8.68 ± 2.76
7.66 ± 1.92
<0.001*
0.001
0.13
0.025
Me-Me’
6.29 ± 1.34
7.17 ± 1.56
7.45 ± 1.93
<0.001*
0.043
0.002
0.5
TABLE 5: Comparison and post-hoc analysis of soft tissue chin thickness among various vertical
facial patterns in females
High: Hyperdivergent > 37°, Normal: Normal angle (32° ± 5°), Low: Hyperdivergent < 27°
Note: (*): Statistically significant (p-value<0.000)
(a) One-way ANOVA (comparison of STC parameters among various facial vertical divergences (Normal, Low, High angle)
(b) Post-hoc analysis: Difference between groups through the Tukey test
ANOVA: analysis of variance
Discussion
Evaluation of soft tissues is crucial in diagnosing conditions, planning treatments, and achieving facial
harmony. Research has shown that considering soft tissue features significantly enhances treatment
outcomes. The soft tissue profile is extensively studied in orthodontics, often using lateral cephalometric
radiographs. It's commonly assumed that the shape of the soft tissue outline greatly influences facial
aesthetics. Studies have indicated that not only the lips but also the position of the chin has a significant
effect on the aesthetics of the lower face [12].
This cross-sectional study was carried out to compare STC thickness in various mandibular divergence
patterns. Our findings showed statistical differences in STC thickness parameters among various vertical
facial divergences. The vertical growth in patients can affect their treatment planning. This sort of growth
stays longer than sagittal and transverse growth. In orthodontics, three vertical facial patterns can be seen:
normo-divergent, hypo-divergent, and hyper-divergent. Growth in the vertical dimension can affect the soft
tissues of the face [13]. Chin morphology can have a significant impact on facial profile and a retrusive chin
can render the profile convex.
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There is a scarcity of literature regarding soft tissue cephalometric norms specifically for individuals of
Pakistani descent. Existing studies in this area have primarily concentrated on dentofacial patterns rather
than conducting comprehensive soft tissue analyses. One such study by Sattar et al. (2018) compared
Pakistani adults with established standards in orthodontics [14]. Their findings indicated that the Pakistani
population tends to exhibit a more convex soft tissue profile in comparison to the established standards of
Tweed and Steiner. This observation was attributed in part to variations in the shape of the nose and the
morphology of the lips among Pakistani individuals. However, despite these initial findings, further research
is needed to fully elucidate the soft tissue cephalometric norms specific to the Pakistani population.
Our study found that the most common vertical facial pattern was normal (n=104, 53.33%), followed by high
angle (n=50, 25.64%), and the least was low angle (n=41, 21.035). The mean STC thickness in the high-angle
group was 7.940 ± 2.87 mm, 11.50 ± 2.26 mm in the low-angle group, and 11.83 ± 2.53 mm in the normal
group. Macari et al. (2014) conducted a study on 190 patients to compare STC in various vertical facial
patterns. All STC thicknesses had the highest measurements in the hypodivergent group and gradually
decreased across the groups, the lowest being in the hyperdivergent group. These results are consistent with
our findings [11]. Another study by Ashraf K et al. (2018) concluded that soft tissue chin thickness (PogPog'), (Gn-Gn'), and (Me-Me') was found to be statistically significant only between the hyperdivergent and
hypodivergent groups [1].
Our study aligns with the findings of Celikoglu et al. (2014) who concluded that in both women and men, the
high-angle group exhibited the lowest soft tissue thickness values. Specifically for women, the thickness
values at pogonion were significantly smaller in the high-angle group. Furthermore, the low-angle and
normal-angle groups demonstrated comparable thickness values [9]. Somaiah et al. (2017)
observed statistically significant differences between men and women across different facial types. In the
low mandibular divergence pattern, a highly significant difference was observed for Pog-Pog' between
genders. In the medium-low divergence pattern, there were no significant differences in Pog-Pog', Gn-Gn',
and Me-Me'. However, in the medium-high divergence pattern, a highly significant difference was observed
for Pog-Pog' between genders, and the mean for Gn-Gn' was significant. In the high mandibular divergence
pattern, there were no significant differences in Pog-Pog', Gn-Gn', and Me-Me' between genders [15].
Comparing our results with those of other researchers is challenging due to the scarce literature available on
this topic. The variances between our findings and those of other studies could stem from differences in
race, age groups studied, and the sizes of the samples. There's a notable gap in studies that examine and
compare the thickness of the soft tissue around the chin and the length and thickness of the upper lip across
different vertical discrepancies. Additional research in this area could offer valuable insights, enhancing our
ability to diagnose and develop treatment plans for orthodontic patients more effectively.
The limitations of our study are primarily related to the sample size and the distribution of participants.
First, the limited sample size may restrict the generalizability of our findings to the broader population.
Second, there was an unequal distribution of gender within our study sample, which could potentially
introduce bias or limit the applicability of our results across genders. Lastly, the unequal distribution of
facial types among participants might have influenced the outcomes, possibly affecting the reliability of
comparisons across different facial morphology categories. These limitations highlight the need for caution
in interpreting our results and underscore the importance of conducting future research with larger, more
evenly distributed samples to validate and expand upon our findings.
Conclusions
Within the limitations of this study, the thickness of the soft tissue chin has a significant association with
vertical facial divergence. While planning orthognathic surgery of the mandible or genioplasty, due
consideration should be given to vertical divergence of the face to avoid unwanted facial changes.
Additional Information
Author Contributions
All authors have reviewed the final version to be published and agreed to be accountable for all aspects of the
work.
Concept and design: Muhammad Noman
Acquisition, analysis, or interpretation of data: Muhammad Noman, Munawar Manzoor Ali, Gulsana
Hashmi, Mazhar Hussain, Rida Mujeeb, Usman Yousaf
Drafting of the manuscript: Muhammad Noman, Munawar Manzoor Ali, Usman Yousaf
Critical review of the manuscript for important intellectual content: Muhammad Noman, Gulsana
Hashmi, Mazhar Hussain, Rida Mujeeb, Usman Yousaf
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Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Sharif Medical and
Dental College Ethical Comittee issued approval 319-AD/PG/R/SMDC. This is to certify that Dr. Muhammad
Noman (Senior Registrar, Department of Orthodontics, Sharif Medical & Dental College Lahore, is
conducting research titled “Comparison of soft tissue chin thickness in Adult Patients with various
mandibular divergence patterns”. No invasive intervention is required in this study and there will be no
financial burden on the participants. The record will be kept secret and can be published. Animal subjects:
All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services
info: All authors have declared that no financial support was received from any organization for the
submitted work. Financial relationships: All authors have declared that they have no financial
relationships at present or within the previous three years with any organizations that might have an
interest in the submitted work. Other relationships: All authors have declared that there are no other
relationships or activities that could appear to have influenced the submitted work.
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