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 Table of Contents  
FORENSIC ODONTOLOGY SECTION: ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 3  |  Page : 242-246

Mandibular ramus: A predictor for sex determination - A digital radiographic study


1 Department of Oral Medicine and Radiology, Mamata Dental College and Hospital, Khammam, Telangana, India
2 Department of Oral and Maxillofacial Pathology, Mamata Dental College and Hospital, Khammam, Telangana, India

Date of Submission31-Dec-2016
Date of Acceptance07-Nov-2017
Date of Web Publication20-Nov-2017

Correspondence Address:
Kotya Naik Maloth
Department of Oral Medicine and Radiology, Mamata Dental College and Hospital, Khammam, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.JIAOMR_170_16

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   Abstract 

Aim: To evaluate mandibular ramus linear measurements on digital panoramic radiographs and to assess the usefulness of mandibular ramus in sex determination. Material and Methods: A retrospective study was conducted on 100 patients (50 males and 50 females) using digital panoramic radiographs of Khammam population with age ranging from 20 to 50 years. Standard digital panoramic radiographs were taken without any errors by Sirona, ORTHOPHOS XG 5 machine. The following five mandibular linear measurements were performed in cm such as upper ramus breadth, lower ramus breadth, condylar ramus height, projective ramus height, and coronoid ramus height. The obtained data were analyzed with the software SPSS 13.0 for statistical analysis using discriminate methods. Results: In the present study, all the linear measurements of mandibular ramus on digital panoramic radiographs showed a statistically significant difference between the genders. Conclusion: We conclude that the use of mandibular ramus is recommended as an aid for sex determination in forensic science due to their unique feature of sexual dimorphism.

Keywords: Linear discriminant function analysis, mandibular ramus, sexual dimorphism, sex determination


How to cite this article:
Maloth KN, Kundoor VK, Vishnumolakala SL, Kesidi S, Lakshmi MV, Thakur M. Mandibular ramus: A predictor for sex determination - A digital radiographic study. J Indian Acad Oral Med Radiol 2017;29:242-6

How to cite this URL:
Maloth KN, Kundoor VK, Vishnumolakala SL, Kesidi S, Lakshmi MV, Thakur M. Mandibular ramus: A predictor for sex determination - A digital radiographic study. J Indian Acad Oral Med Radiol [serial online] 2017 [cited 2019 Oct 20];29:242-6. Available from: http://www.jiaomr.in/text.asp?2017/29/3/242/218714


   Introduction Top


Sex determination was considered the foremost step in identification of cases at mass disasters, explosions, air hurricanes where bodies are damaged beyond recognition and is the most challenging task for forensic experts for identification, followed by age and stature estimation as both are sex dependent.[1],[2] Generally, stature of the skeleton elements are good morphological indicators of sexual dimorphism in more than 95% of cases, but in mass disasters only some fragments of bones are found resulting in difficulty in obtaining correct diagnosis.[3],[4] As evident from the previous studies done by Rosing FW,[2] Saini V et al.,[5] Hu KS et al.,[6] Scheuer L,[7] and Raj JD et al.,[8] pelvis and skull bones are the most reliable source among human bones for sex determination, providing accuracy more than 92%.[5] But in the absence of pelvis bones or non-intact skull bones, mandible becomes a source and plays a major role in sex determination and is considered most dimorphic, more durable, largest, and strongest bone of skull.[5],[6]

Mandibular ramus can be differentiated between sexes, based on the stages of mandibular development, growth rates, and duration. Owing to the different masticatory forces exerted by males and females, the size and shape of the mandible varies where males have bigger and more robust mandible than females.[7] Moreover, occlusal status, age of the subject, and constant remodeling of the mandibular bone also results in morphological changes of the mandible.[8],[9] Although various anatomical landmarks exist, the use of gonial angle for estimation of age and sex showed controversial results by Taleb NSA et al.,[1] and Huumonen S et al.;[9] hence, in the present study different ramus metric measurements on digital panoramic images were considered as indicators for sex determination and we aim to determine the efficacy of mandibular ramus in sex determination.


   Materials and Methods Top


A retrospective study was conducted using digital panoramic radiographs of 100 subjects (50 males and 50 females) with age ranging from 20 to 50 years. After obtaining ethical clearance, standardized digital panoramic radiographs of patients taken as part of pretreatment planning for implants, extractions of third molars, and for periodontal diseases were selected from the archives of the radiology department. Good quality standard digital panoramic radiographs (Sirona, ORTHOPHOS XG 5) of completely dentate and partially edentulous patients were selected for the study and poor quality with any pathological lesions, fracture, or developmental disturbances of the mandible and edentulous mandibles were excluded from the study. The standardized exposure parameters 66 kVp, 8 mA, and 14s were employed for every panoramic radiograph and assessed by taking measurements unilaterally (on left side).

The digital panoramic images were saved in a JPEG file format and exported to the SIDEX 2.5 software (Sirona Dental Systems, USA) where mandibular ramus linear measurements were performed. This study was conducted in the department of oral medicine and radiology, Mamata Dental College and Hospital, Khammam, Telangana, India. The following mandibular ramus linear parameters were measured after image calibration by using mouse-driven method [3] (moving the mouse and drawing lines using chosen points on the digital panoramic image) [Figure 1] and [Figure 2] in cm:[1],[3]
Figure 1: Diagram showing mandibular ramus measurements adapted from Saini et al.

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Figure 2: The five linear ramus measurements on digital panoramic radiograph (R1: upper ramus breadth, R2: lower ramus breadth, AB: condylar ramus height, BC: coronoid ramus height, AD: projective ramus height)

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  1. Upper ramus breadth (R1): the distance between the most anterior to the most posterior point of the ramus passing through the sigmoid notch
  2. Lower ramus breadth (R2): the distance between the most anterior to the most posterior point of the ramus at the level of the occlusal plane along a line parallel to the previous one. (An average ramus breadth value of R1 and R2 was calculated for each side and used for further analysis)
  3. For standardization, a horizontal orientation line was digitally traced passing through the summit of the gonial angle and used for the following measurements:
  4. Condylar ramus height (A–B): the distance from the condylion (the craniometric point at the tip of the mandibular condyle) (A) to the intersection of the orientation line with the inferior border of the ramus (B)
  5. Projective ramus height (A–D): the projective distance between the condylion (A) and the orientation line (D)
  6. Coronoid ramus height (C–B): the distance between coronion (the craniometric point at the tip of the coronoid process of the mandibular) (C) and the intersection of the orientation line with the inferior border of the ramus (B).


Statistical analysis

The data obtained was collected and assessed by an oral and maxillofacial radiologist who did not participate in taking measurements. All the measurements were performed by well experienced two oral and maxillofacial radiologists. Both the observers were blinded to the sex and age of the participants where no evidence of sex or age was visible on the panoramic radiographs. Both the observers were also blinded to the measurements taken individually. The data obtained presented as minimum, maximum, mean, standard deviation (SD) and median values were exported to the software SPSS13.0 (SPSS Statistics for Windows, Version 21.0. Chicago: SPSS Inc.) for statistical analysis using discriminate methods.


   Results Top


All the variables showed good reliability, including both intra-observer and inter-observer (in the range of 0.984 to 0.999). Inter and Intra observer results were statistically significant (P< 0.05). [Table 1]. Descriptive statistical analysis of five mandibular ramus linear measurements and associated univariate F ratios for male and female subjects are presented in [Table 2]. We observed that each variable was a statistically significant predictor in classifying given subjects (P< 0.001**).
Table 1: Table with all the variables showing good reliability: both intra-observer and inter-observer

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Table 2: Descriptive statistical analysis of five mandibular ramus linear measurements

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The mean measurement values were higher for males [R1-38.90; R2-34.22; AB-70.72; AD-69.59, and CB-68.37, respectively] compared to females [R1-35.18; R2-32.54; AB-65.43; AD-64.55, and CB-63.20, respectively]; values are shown in [Table 2] and [Graph 1]. The F-static values of mandibular measurements expressing the sexual dimorphism were minimum: Lower Ramus Breadth (R2) followed by Projective Ramus Height (AD) and Condylar Ramus Height (AB) [Table 2].



Sex determination

A discriminant analysis was performed to predict the sex. There was a significant difference between the measurements of males and females, but condylar ramus height was the only significant value which acts as predictor for sex [Table 3]. The linear discriminate (D) function equation is as follows:
Table 3: Linear discriminate function variables

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DMale= − 181.017 + 0.664 (D1 Max Ramus Breadth) + 4.839 (D2 Min Ramus Breadth) +5.131 (Condylar Max Ramus Ht) – 3.541 (Projective Ht of Ramus) + 0.773 (Condylar Ht)

DFemale= − 158.348 + 0.186 (D1 Max Ramus Breadth) + 5.039 (D2 Min Ramus Breadth) +4.741 (Condylar Max Ramus Ht) – 3.228 (Projective Ht of Ramus) + 0.680 (Condylar Ht)

Considering all the variables, the results revealed that 70% of the males, 78% of the females and overall 74% of all the cases were correctly identified [Table 4]. In the present study, the sectioning point was found to be −0.775. Values greater than this sectioning point indicate male and vice versa [Table 5].
Table 4: Prediction accuracy

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Table 5: Standardized and structure coefficients in original samples

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   Discussion Top


Sex determination from human remains is the foremost and fundamental step in forensic science and anthropology, followed by age and stature estimation as both are sex dependent.[2] In recent times, sex determination plays a vital role in medico-legal cases and in identification of mass disasters with the help of human remains such as fragmented jaws and dentitions.[10] Sex determination based on morphological marks may lead to misdiagnoses, whereas measurements and morphometry methods give accurate results.[11],[12] Mandible is considered most for sex determination due to its unique features such as it being a sexually dimorphic, largest, and strongest bone of skull and it is often recovered largely intact.[13] The greatest morphological changes in size and remodeling during growth are seen at mandibular ramus and condylar region.[3] Hence, in the present study the mandibular ramus and condylar region was selected for sex determination.

In the present study, panoramic radiographs were considered because most oral clinicians routinely and most commonly used screening tools for the diagnosis of oral lesions. Although it is a technique sensitive procedure, we found that panoramic radiographs provide accurate anatomic measurements without any errors. According to Kambylafkas et al.,[14] the use of panoramic radiograph for evaluation of total ramal height is reliable and an asymmetry of more than 6% is an indication of a true asymmetry. Schulze et al.,[15] found that the most reliable measurements were obtained for linear objects in the horizontal plane and digital measurements are sufficiently accurate for clinical use.

In the present study, standardized panoramic radiographs with mandibular ramus linear measurements were subjected to discriminant function analysis. The results showed that males had statistically significant higher mean values than females. This was in agreement with Saini V et al. (2011),[5] Indira AP et al. (2012),[3] Vodanovic M et al. (2006),[10] Al-Shamout et al. (2012),[16] Rai R et al. (2007),[17] and Giles E (1964)[18] where all the mandibular ramus linear measurements were higher in males than females. The mandibular ramus demonstrated greatest univariate sexual dimorphism in terms of minimum ramus breadth, condylar height, followed by projective height of ramus. Overall, predicted accuracy rate using all five variables was 74%.

Saini V et al. (2011)[5] conducted a study on dry mandible of North Indian population (92 males, 24 females, mean age 37.4 years) and found that all the mandibular ramus linear measurements were higher in males than females (coronoid height: 61.68 mm and 54.89 mm, projective height: 53.89 and 47.45, condylar height: 60.67 and 54.46, maximum breadth: 42.81 and 40.34 and minimum breadth: 31.29 and 29.65 in males and females, respectively) and showed significant sexual dimorphism with an overall accuracy of 80.2%. Similarly, Indira AP et al. (2012)[3] conducted a study on Bangalore population and found that all linear ramus measurements on orthopantomographs (50 males, 50 females ageing 20–50 years) were significantly higher for males compared to females (coronoid height: 119.70 and 111.15, projective ramus height: 129.05 and 120.82, condylar height: 131.30 and 123.27, maximum breadth: 74.20 and 68.98 and minimum breadth: 51.35 and 46.96 in males and females, respectively) with an overall accuracy rate of 76%. Additionally, Giles E (1964)[18] conducted a study on mandible in American Whites and Negroes for sex determination using anthropometric measurements and concluded that mandibular ramus height, maximum ramus breadth, and minimum ramus breadth as highly significant, with an accuracy rate of 85%.

The results of the present study were contradictory to Hill (2000),[19] Haun (2000),[20] and Balci et al. (2005),[21] where Hill conducted a study on 158 mandibles for the presence of flexure as a morphological indicator of sex, as defined by Loth and Henneberg. Finally, they concluded that, low overall accuracy, an invalid scoring system and high intra-observer error indicated that the mandibular ramus flexure is an unreliable technique for sex determination.[19]

Generally, the development of the human skeleton such as the overall size and thickness of the bone is greater in males compared to females, but it is not true, since various factors that influence the development of bone and their appearance such as socio-environmental factors like nutrition, physical exercises, climate, and any pathologies.[22] The mandibular ramus showed high sexual dimorphism and proved to be beneficial in sex determination. Hence, the use of mandibular ramus is recommended as an aid for sex determination in forensic analysis. The limitation of the present study is inability to reliably assign sex in the sub-adult range and inability to assess the gender in cases of edentulous patients. However, further studies with large sample size from diverse regions and with different imaging modalities are recommended to set our populations for sex determinations in forensic analysis.


   Conclusion Top


The results of the present study proved that the mandibular ramus plays a major role in sex determination due to its unique high sexual dimorphism and also possesses resistance to damage and disintegration processes. Hence, we conclude that the use of mandibular ramus is recommended as an aid for sex determination in forensic science.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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Taleb NS, Beshlawy ME. Mandibular ramus and gonial angle measurements as predictors of sex and age in an Egyptain population sample: A digital panoramic study. J Forensic Res 2015;6:308.  Back to cited text no. 1
    
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Rosing FW, Graw M, Marré B, Ritz-Timme S, Rothschild MA, Rotzscher K, et al. Recommendations for the forensic diagnosis of sex and age from skeletons. Homo 2007;58:75-89.  Back to cited text no. 2
    
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Raj JD, Ramesh S. Sexual dimorphism in mandibular ramus of south Indian population. Antrocom Online Journal of Anthropology 2013;9:253-8.  Back to cited text no. 8
    
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Huumonen S, Sipilä K, Haikola B, Tapio M, Raustia AM, Söderholm AL, et al. Influence of edentulousness on gonial angle, ramus and condylar height. J Oral Rehabil 2010;37:34-8.  Back to cited text no. 9
    
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Vodanovic M, Dumancic J, Demo Z, Mihelic D. Determination of sex by discriminant function analysis of mandibles from two Croatian archaeological sites. Acta Stomatol Croat 2006;40:263-77.  Back to cited text no. 10
    
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Franklin D, Oxnard CE, O'Higgins P, Dadour I. Sexual dimorphism in the subadult mandible: Quantification using geometric morphometrics. J Forensic Sci 2007;52:6-10.  Back to cited text no. 11
    
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Franklin D, O'Higgins P, Oxnard CE. Sexual dimorphism in the mandible of indigenous South Africans: A geometric morphometric approach. South African Journal of Science 2008;104:101-6.  Back to cited text no. 12
    
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Franklin D, O'Higgins P, Oxnard CE, Dadour I. Discriminant function sexing of the mandible of indigenous South Africans. Forensic Sci Int 2008;179:84.  Back to cited text no. 13
    
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Kambylafkas P, Murdock E, Gilda E, Tallents RH, Kyrkanides S. Validity of panoramic radiographs for measuring mandibular asymmetry. Angle Orthod 2006;76:388-93.  Back to cited text no. 14
    
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Al-Shamout R, Ammoush M, Alrbata R, Al-Habahbah A. Age and gender differences in gonial angle, ramus height and bigonial width in dentate subjects. Pakistan Oral and Dental Journal 2012;32:81-7.  Back to cited text no. 16
    
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Haun SJ. Brief Communication: A study of the predictive accuracy of mandibular ramus flexure as a singular morphologic indicator of sex in an archaeological sample. Am J Phys Anthropol 2000;111:429-32.  Back to cited text no. 20
    
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Balci Y, Yavuz MF, Cagdir S. Predictive accuracy of sexing the mandible by ramus flexure. Homo 2005;55:229-37.  Back to cited text no. 21
    
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Bhagwatkar T, Thakur M, Palve D, Bhondey A, Dhengar Y, Chaturvedic S. Sex determination by using mandibular ramus - A forensic study. J Adv Med Dent Sci Res 2016;4:1-6.  Back to cited text no. 22
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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