Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2020  |  Volume : 31  |  Issue : 2  |  Page : 224--228

Comparison of soft tissue chin thickness at different levels of chin in subjects with various growth patterns


Javed Sodawala1, Amit Akolkar1, Fatema Sodawala2, Sumit Gandhi1, Shaheen Hamdani1, Sayyed Muhammad Ali1,  
1 Department of Orthodontics and Dentofacial Orthopaedics, Rungta College of Dental Sciences and Research, Bhilai, Chhattisgarh, India
2 Department of Prosthodontics and Crown & Bridge, Rungta College of Dental Sciences and Research, Bhilai, Chhattisgarh, India

Correspondence Address:
Dr. Amit Akolkar
Sushil Nagar, Gopal Nagar Road, Near Sai Mandir, Amravati - 444 607, Maharashtra
India

Abstract

Aims and Objectives: To evaluate the association between mandibular growth pattern and soft tissue chin (STC) thickness measured at different chin levels and the gender differences in STC thickness at these different chin levels. Materials and Methods: Pretreatment lateral cephalograms of 161 subjects aged 18–45 years were selected, and subjects were divided into 4 groups depending on mandibular growth pattern defined by the mandibular plane to cranial base angle. The STC thicknesses were measured at pogonion (Pog), gnathion (Gn), and menton (Me). Group difference was evaluated using analysis of variance. Results: STC thickness was greater (p < .05) in the low-angle group, and it gradually decreased across the groups, the least being in the high-angle group. No sexual dimorphism was observed among the groups (p > .05). Conclusion: This study suggests that STC thickness measurements were smaller in high-angle group compared to low-angle group.



How to cite this article:
Sodawala J, Akolkar A, Sodawala F, Gandhi S, Hamdani S, Ali SM. Comparison of soft tissue chin thickness at different levels of chin in subjects with various growth patterns.Indian J Dent Res 2020;31:224-228


How to cite this URL:
Sodawala J, Akolkar A, Sodawala F, Gandhi S, Hamdani S, Ali SM. Comparison of soft tissue chin thickness at different levels of chin in subjects with various growth patterns. Indian J Dent Res [serial online] 2020 [cited 2021 Oct 25 ];31:224-228
Available from: https://www.ijdr.in/text.asp?2020/31/2/224/284571


Full Text



 Introduction



The facial harmony and balance are determined by the facial skeleton and its soft tissue drape. Recently, the field of orthodontics has experienced a paradigm shift with specific emphasis on soft tissues around the oral cavity.[1] The final facial contours are determined by the soft tissues, and these can be altered by growth and orthodontic treatment.[2]

The soft tissue pogonion is an important facial landmark that determines the degree of profile convexity. The vertical growth of the jaws carries pogonion (Pog) downward, while their antero-posterior growth carries it forward. This battle starts early in life and continues till facial growth is completed.[3]

The covering facial soft tissues (skin, fat, and muscles) can develop in proportion or disproportion to the corresponding skeletal structures. The facial esthetics depends upon facial structures that mainly include length, thickness, and tonicity of soft tissue. The variations between skeletal and soft tissues can cause a disproportion between the position of the underlying bony structures and the facial appearance.[4]

Most studies of facial soft tissues in particular soft tissue chin (STC) thickness are primarily concerned with changes after orthodontic treatment. There is a need to investigate soft tissue characteristics in different growth pattern. This knowledge will assist in orthodontic treatment planning and also help to establish a specific soft tissue prognosis for each growth pattern.[5],[6]

Macari and Hanna compared the STC thickness in Lebanese adult population among various mandibular divergence patterns.[7] There is scant literature regarding this for Indian population. The purpose of this study were to evaluate the association between mandibular growth pattern and STC thickness measured at different chin levels and the gender differences in STC thickness at these different chin levels in Bhilai population.

 Materials and Methods



Pretreatment lateral cephalograms of 161 subjects (72 males and 89 females) aged 18–45 years were collected from the archives of Department of Orthodontics and Dentofacial Orthopedics of our college. The standardized lateral cephalograms were taken using ORTHOPHOS XG5 (Sirona dental system, Bensheim, Germany) in natural head position at rest position with no lip strain. Patients who had undergone previous orthodontic and/or orthognathic surgery, patients with craniofacial anomalies, or presence of a non-continuous soft tissue contour at the level of the chin indicating a chin strain were excluded from the study. The ethical permission for conducting this study was obtained from Institutional Ethics Committee of the concerned college (RCDSR/MDS/SYNOPREG/2015/30A).

Patients were divided into 4 groups according to divergence pattern defined by the mandibular plane to cranial base angle (MP/SN angle): Low (L) MP/SN ≤27˚ (n = 48; 21 males, 27 females); Medium-Low (ML) = 27˚<MP/SN <32˚ (n = 39; 18 males, 21 females); Medium-High (MH) = 32˚<MP/SN <37˚ (n = 42; 18 males, 24 females); and High (H) MP/SN ≥37˚ (n = 32; 15 males, 17 females).[7]

The STC thickness was measured at 3 different levels: Pog-Pog' = length between bony Pog and its horizontal projection (Pog') over the vertical passing through soft tissue Pog, Gn-Gn' = distance between bony Gnathion (Gn) and soft tissue Gn', and Me-Me' = distance between bony Menton (Me) and its vertical projection (Me') on the horizontal passing through soft tissue Me [Figure 1].{Figure 1}

Statistical method

SPSS software (Chicago, IL) Version 18.0 was used for statistical computation. The age difference between genders was evaluated using student's t-test. The analysis of variance and Tukey's post-hoc test were used for multiple comparisons (cephalometric angular and STC measurements) among the 4 groups. The analysis of variance and post-hoc test were also used to compare the studied parameters in males and females separately among the 4 groups, and the comparison of differences between genders within each group was achieved with the Mann-Whitney test.

The Pearson correlation coefficient gauged the relationship between STC measurements and mandibular divergence angle. The statistical significance was set at p = 0.05. To determine the measurement error, all the tracings and measurements were performed by single investigator on 18 randomly selected cephalograms (approximately, 10% of the sample).

 Results



The age was not statistically significantly different for males or females across the 4 groups and within each of the 4 groups [Table 1]. When comparing all the groups, STC thickness was greater in the low-angle group (L), and it gradually decreases across the groups, the least being in the high-angle group (H). At the level of Gn, the distance Gn-Gn' was statistically significantly different between groups L-H (p <.05). At the level of Me, Me-Me' was statistically significantly different between groups L-H, ML-H (p <.05). At the level of Pog, Pog-Pog' was statistically significantly different between groups L-H, ML-H, and MH-H (p <.05) [Table 2].{Table 1}{Table 2}

Chin measurements were not statistically significantly different among males and females across all groups. There were statistically significant differences at the level of Pog, Gn, and Me in males, and no statistically significant differences at all the levels in females. According to post-hoc test, males showed statistically significant differences (p <.05) between L-H and ML-H for STC thickness at Pog, L-H at Gn and L-H and ML-H at Me, and females showed no statistically significant differences (p <.05) for STC thickness at Pog, Gn, and Me [Table 3].{Table 3}

No statistical difference was found between genders at different levels of STC thickness using to Mann-Whitney test [Table 4]. The statistically significant correlations between STC thickness and cephalometric measurements were negative and low [Table 5]. The intra-class correlation coefficients for the intra-examiner repeated measurements were high (r = 0.987) for all measurements.{Table 4}{Table 5}

 Discussion



The soft tissues that cover bones and teeth are highly variable in thickness, and variations are greater in subjects with different growth pattern. The convexity of the profile depends upon the thickness of the overlying soft tissues more than actual hard tissues.[8]

There is need to understand the interactions established between the hard and soft tissues in the different growth patterns. The stomatognathic system is highly capable of developing adaptive patterns because of its plasticity. Kuyl et al. suggested that the soft tissues of the face are dynamic and can develop independently of the hard structures.[9]

Facial profile assessment can be affected by factors including ethnic, racial, and the time aspects. An inverse correlation was reported between the convexity of skeletal and soft tissues profile. The tendency of reduction of the convexity of the skeletal profile occurs because of the protrusion of the chin. The soft tissue profile does not behave the same indicating a different mechanics of growth for soft tissue thickness.[2]

Macari and Hanna compared STC thickness in adult Lebanese population among various mandibular divergence pattern.[7] They found that STC thickness is thinner at Gn and Me in hyperdivergent facial pattern, whereas in our study, the STC thickness is thinner at all the chin levels in vertical growth pattern which is similar to studies conducted by Subramaniam et al.[10] and Somaiah et al.[11]

Feres et al. assessed the soft tissue size between different facial patterns in Brazilian children and found out that STC thickness of upper lip and lower lip at the level of Pog did not differ significantly between different facial patterns.[6] Blanchette et al. performed a longitudinal cephalometric study of the soft tissue profile of short and long face syndromes from 7–17 years in individuals of Northern European ancestry. They found out that all chin measurements including the thickness of soft tissue at point B and Pog were significantly larger thickness in the long vertical patterns. He suggested that this might have been nature's way of compensating for the shorter mandibular corpus length in an effort to mask the condition and to provide a more normal facial appearance. The converse was true for the short pattern that showed a thinner tissue drape.[12] These findings are contradictory to our study. In our study, the STC thickness was greater in low-angle group and it gradually decreased across the groups with the least being in the high-angle group.

Taki et al. suggested that the soft tissues chin thickness in Persian adults was significantly larger in men than in women.[1] Similar results were obtained by Basciftci et al., who reported that Anatolian Turkish men have a more prominent chin than women.[13] Macari and Hanna also found out that STC thickness is greater in males than female counterparts.[7] No sexual dimorphism was observed in our study.

The contrasting results of the different studies suggest that the growth of soft tissue is different in individual of different races and gender. The compensatory growth mechanism that plays a role in one race may not occur in the other. Further, studies should be performed with a larger sample and using 3 dimensional diagnostic aids for better understanding of the growth and development in all the 3 planes.

 Conclusion



It was found out that soft tissue thickness measurements were smaller in high-angle group compared to low-angle group. High-angle group exhibited a statistically significantly thinner STC at Gn and Me in comparison with low-angle group. No sexual dimorphism was seen for STC measurements at level of Pog, Gn, and Me.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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