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ORIGINAL ARTICLE | |
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Accuracy of mandibular rami measurements in prediction of sex
B Kartheeki1, Abhishek Singh Nayyar1, Y Udaya Sindhu2, N Lakshmana3
1 Department of Oral Medicine and Radiology, Saraswati-Dhanwantari Dental College and Hospital and Post Graduate Research Institute, Parbhani, Maharashtra, India
2 Department of Oral Medicine and Radiology, St. Joseph Dental College and Hospital, Eluru, Andhra Pradesh, India
3 Department of Oral Medicine and Radiology, Sri Sai Dental College and Hospital, Srikakulam, Andhra Pradesh, India
Date of Web Publication | 16-Jun-2017 |
Correspondence Address:
Abhishek Singh Nayyar
44, Behind Singla Nursing Home, New Friends’ Colony, Model Town, Panipat – 132 103, Haryana
India
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/amhs.amhs_66_16
Background and Objective: Sex of an individual can be determined by means of skeletal indicators when soft tissues are not available for analysis. Furthermore, when entire skull is not available for analysis, mandible plays a vital role in the prediction of sex. As various studies have proven the accuracy of panoramic radiographs in providing anatomical measurements, the present study was conducted using digital orthopantomographs (OPGs) in the south Indian population for the same. The aim of the present study was to measure and compare various measurements of the ramus in mandible on digital OPGs and to assess the usefulness of such measurements in the prediction of sex in an individual. Materials and Methods: A cross-sectional, observational study was carried out using 500 digital OPGs with five rami measurements taken for each radiograph in the south Indian population. The determination of sex was done by discriminant function analysis. Results: All the variables were found to be good predictors for prediction of sex in the study with condylar height/maximum ramus height; projective height of ramus; and coronoid height, being highly significant. Conclusion: This study on rami measurements showed that significant sex-related dimorphism is evident in rami of mandibles indicating its potential usage in mass disasters and otherwise in the prediction of sex in individuals with disputed identity.
Keywords: Digital orthopantomographs, mandibular ramus, prediction of sex
How to cite this article: Kartheeki B, Nayyar AS, Sindhu Y U, Lakshmana N. Accuracy of mandibular rami measurements in prediction of sex. Arch Med Health Sci 2017;5:50-4 |
How to cite this URL: Kartheeki B, Nayyar AS, Sindhu Y U, Lakshmana N. Accuracy of mandibular rami measurements in prediction of sex. Arch Med Health Sci [serial online] 2017 [cited 2022 Sep 10];5:50-4. Available from: https://www.amhsjournal.org/text.asp?2017/5/1/50/208206 |
Introduction |
Even the minutest remains from the body, helpful for identification, should not be neglected.[1] The total number of affected and killed population is significantly increasing in mass disasters. The World Disasters Report published by the International Federation of Red Cross And Red Crescent Societies in 2012 revealed that the total number of people affected and killed in mass disasters in 2011 itself was around 17 crores and 30 thousand, respectively.[2] The considerably higher number of affected and killed population signifies the role of forensic anthropologists in personal identification in mass disasters.
The role of forensic anthropologists is to create biological profiles of unknown remains that lead to personal identification in such mass disasters. Prediction of sex is one of the leading questions when formulating the biological profile of an individual.[3]
There are several methods for prediction of sex. Rösing et al. recommended a first evaluation phase by morphologic character before moving to the second phase of molecular analysis.[4],[5] When soft parts are unavailable, prediction of sex can be based only on the characteristics of the skeleton.[1],[6]
Skull is one of the highly useful remains for the creation of biological profiles in mass disasters; however, in most of the situations, the entire skull is not available, and the technical procedure has to be based on the fragmented bones of the skull. In such cases, mandible plays a vital role in the prediction of sex in an individual. Humphrey et al. stated that sexual dimorphism is reflected in mandibular ramus than the body.[7],[8]
Radiographic examination plays a significant role in diagnosing nonaccidental injuries in children, in medical negligence, and in establishing biological aging in the disputed cases.[9] Various forensic experts have claimed that prediction of sex by radiographic study of skulls is a reliable method which provides an accuracy of up to 80%–100%.[1],[10],[11]
Hence, this study aimed at evaluating the reliability of mandibular rami in the prediction of sex for its use in forensic analysis and anthropology.
Materials and Methods |
This was a cross-sectional, observational study conducted in the Department Of Oral Medicine and Radiology using 500 digital orthopantomographs (OPGs) taken with the help of SIRONA digital panoramic and cephalometric system in the south Indian population in the age range of 20–60 years who visited the department for their routine radiographic examination after approval from the Institutional Ethical Committee.
Pathological, fractured, and deformed mandibles were excluded from the study. Mandibular rami measurements were carried out using SIDEXIS-XG software. Radiographs of the patients who were not having pathological, fractured, or deformed mandibles were collected and stored along with their demographic data. Each image was imported into the SIDEXIS-XG software. The tool “Measure Length” was selected in the software and two points were selected using the mouse-driven method between which the length was displayed by the software [Figure 1] and [Figure 2].
Figure 1: Digital orthopantomograph showing mandibular ramus measurements. Variable A: Maximum ramus width: Distance between most anterior and posterior points on the mandibular ramus as represented in Figure as 1; Variable B: Minimum ramus width: Smallest anteroposterior diameter of the mandibular ramus as represented in Figure as 2; Variable C: Condylar height/Maximum ramus height: Distance between the most superior point on the condyle to the most protruded point on inferior border of the ramus as represented in Figure as 3; Variable D: Projective height of ramus: Distance between the most superior point on the condyle to the lower margin of bone on inferior border of the ramus as represented in Figure as 4; Variable E: Coronoid height: Distance between the most superior point on the coronoid to the most protruded point on inferior border of the ramus as represented in Figure as 5 |
Figure 2: Measurements of mandibular ramus on digital orthopantomograph on monitor using SIDEXIS-XG software |
Variable A: Maximum ramus width: Distance between most anterior and posterior points on the mandibular ramus depicted as 1 in [Figure 1].
Variable B: Minimum ramus width: Smallest anteroposterior diameter of the mandibular ramus depicted as 2 in [Figure 1].
Variable C: Condylar height/maximum ramus height: Distance between the most superior point on the condyle to the most protruded point on inferior border of the ramus depicted as 3 in [Figure 1].
Variable D: Projective height of ramus: Distance between the most superior point on the condyle to the lower margin of bone on inferior border of the ramus depicted as 4 in [Figure 1].
Variable E: Coronoid height: Distance between the most superior point on the coronoid to the most protruded point on the inferior border of the ramus depicted as 5 in [Figure 1].
All the variables obtained were reexamined by two other expert oral radiologists to minimize inter- and intra-observer variability with the value of the Pearson’s correlation coefficient (r-value) being 0.98. The data were, then, subjected to statistical analysis.
Statistical analysis
The data were analyzed using discriminant functional analysis using SPSS version 13.0 (Statistical analysis was performed with SPSS, version 13, SPSS Inc., Chicago, USA) statistical package. Discriminant function analysis was used to determine the variables showing discrimination between naturally occurring groups and to determine which variables were the best predictors.
Results |
Out of the 500 digital OPGs taken, 271 OPGs were of females and 229 were of males. Descriptive statistics of mandibular rami measurements and all variables were found to be the best predictors for prediction of sex in the study with Variable C: Condylar height/maximum ramus height; Variable D: Projective height of ramus; and Variable E: Coronoid height, being highly significant, with P < 0.001. This implies that all variables showed their uniqueness among the individuals considered for the sample, with variables C, D, and E being highly significant in their uniqueness. The associated univariate F-ratios for both the sexes are also shown in [Table 1] and [Graph 1].
Furthermore, it was observed that the mean values were significantly higher in males than females for all variables. All the variables were found to be significant predictors for classifying a given sample based on sex. From the values obtained by linear discriminant function, calculations can be done with the help of the following equations to estimate sex in an unknown sample [Table 2]:
Males: 143.277 + 0.805 (maximum ramus width) +0.538 (minimum ramus width) +3.532 (condylar height) −1.294 (projective height of ramus) +0.833 (coronoid height) and Females: 121.646 + 0.858 (maximum ramus width) +0.666 (minimum ramus width) +3.21 (condylar height) −1.159 (projective height of ramus) +0.636 (coronoid height).
For classifying a given sample as males or females, the maximum value of two equations is considered. Prediction accuracy was calculated for the study sample. With all the variables in consideration, 80.4% of the sample were classified accurately [Table 3].
Among 271 females in the sample, 228 were estimated correctly as females using the above equations while in case of males, among 229 males in the study sample, 174 were estimated as males using the above equations with prediction accuracy being 84.1% among females, 76% among males, and 80.4% for the entire study sample.
In the present study, sectioning point was found to be 0.19. For any unknown sample, for prediction of sex, we calculate the value obtained from the above-mentioned equations using the five variables obtained from the Sidexis software. If the value is greater than this sectioning point, i.e. 0.19, sample is male, and if the value is lesser than this point that indicates a female [Table 4].
Discussion |
Forensic odontology is the study of dental applications in legal proceedings. Recent advances and current trends in forensic odontology include DNA profiling from teeth, palatal rugae and lip print patterns, novel methods of identification of human remains, innovative techniques in bite mark analysis, contemporary methods for prediction of age and sex, and the role of digital panoramic radiography in forensic odontology.
Forensic odontology plays a major role in identification in any sort of mass disaster events that result in multiple fatalities that may not be identified by means of conventional methods. One of the crucial aspects of forensic odontology is to predict sex using fragmented jaws as intact skull is not available for analysis in mass disasters.[10]
Prediction of sex based on morphology is subjective and is likely to be biased, but methods based on measurements from the skull are accurate and provide a more objective criteria with greater accuracy, reliability, and reproducibility.[7],[10]
Digital OPGs have been widely used by the clinicians as a screening modality for the diagnosis of a plethora of oral diseases. The major advantages of this specialized radiography include a broad coverage, low patient radiation dose, ease of examination, and shorter time required to make images while the major drawbacks remain unequal magnification and geometric distortion, ghost images and soft-tissue shadows, and the technique being sensitive to numerous positioning errors.[10],[12],[13],[14] In the present study, the same was used because of the inherent properties of contrast and brightness enhancement and enlargement of images which can provide an accurate and reproducible method of measuring the chosen points.
The selected variables of ramus were chosen because of less chances of alteration in these variables with advancing age compared to measurements of the body of the mandible. Furthermore, there are less geometric errors in the images obtained by digital OPGs in the ramus region compared to midline structures of the mandible.
In the present study, mandibular rami measurements were subjected to discriminant functional analysis. All variables expressed strong sexual dimorphism with the mandibular rami with strongest univariate dimorphism in terms of condylar height, coronoid height followed by projective height of ramus, and maximum and minimum ramus widths giving an overall prediction rate of 80.4% using all the five variables.
Similar results were obtained by the studies conducted by Martin and HrdlicKa who stated that measurements of the mandibular ramus height showed greater sexual dimorphism.[15],[16]
Giles concluded that the height of the symphysis, ramus, and body, mandibular body length, and bigonial diameter were useful measurements with greater sexual dimorphism.[17]
Hanihara did a study on Japanese crania and obtained a higher degree of accuracy using measurements from the calvarium and mandible.[18]
Loth and Henneberg, too, did a similar study on African and American samples and suggested that the degree of flexure of the posterior border of the ramus was as reliable as an indicator for the prediction of sex as the pelvis.[19]
A study conducted by Pokhrel and Bhatnagar on dry mandibles of the Indian population concluded mandibular measurements to be highly significant in the prediction of sex in defined population.[20]
Since fewer studies have been conducted on the population in South India, the present study aimed at evaluating the reliability of mandibular rami in the prediction of sex for its use in forensic analysis and anthropology.
Indira et al. conducted a study and arrived at conclusions similar to our study. The regression equations for their study were − 185.622 + 1.361 for maximum ramus width, +1.087 for minimum ramus width, +2.253 for condylar height/maximum ramus height, −0.717 for projective height of ramus, +0.081 for coronoid height in males while the similar values for females were −161.761 +1.276, +0.948, +2.220, −0.753, +0.063, respectively.[10]
A similar study conducted on radiographic parameters in the south Indian population and Indian immigrants of Tibetan origin using lateral and posteroanterior cephalograms by Naikmasur et al. revealed bizygomatic width, maximum ramus height, and depth of face to contribute most toward sexual dimorphism in both the populations.[21]
Yet another study conducted by Poongodi et al. revealed the mean values of gonial angle and maximum ramus height and width to be significant factors in the prediction of age and gender using digital radiographic method.[22]
A recent study conducted by Samatha et al., also, revealed the P values to be statistically significant for maximum ramus width, condylar height, and projective height of ramus in the prediction of sex in a specified population of South India.[23]
In an another contemporary study conducted by Damera et al., mandibular ramus measurements were subjected to discriminant function analysis and while each of the seven variables including maximum and minimum ramus widths, maximum and projective height of ramus, coronoid height, bigonial angle, and bigonial width measured on the mandibular ramus using OPGs were found to be statistically significant, maximum ramus height expressed the strong sexual dimorphism in terms of minimum ramus breadth, condylar height, projective height of ramus, and bigonial angle followed by the bigonial width. Overall, the prediction rate using all the five variables was 83.8%.[24]
Furthermore, DNA tests in victims of mass disaster can prove helpful in personal identification, but the technique depends on previous medical records for comparison to arrive at specific conclusions. The additional complication of reduced availability of direct reference samples, also, remains a major factor to be dealt with, with a plethora of factors affecting DNA integrity with time.
All these challenges require an approach to the identification process of the victims as an integral effort based on DNA testing as well as forensic anthropology procedures including fingerprints and forensic odontology and radiology wherein forensic odontology and radiology might have a quintessential role to play.[25]
Conclusion |
This study, thus, concludes with the observation that mandibular ramus can be included as one of the skeletal indicators for prediction of sex in forensic analysis and anthropology especially in situ ations where the availability of soft tissues is questionable for analysis. The study found that rami measurements using digital OPGs were reliable indicators in the prediction of sex. Hence, the study suggests the use of mandibular rami in the prediction of sex in forensic anthropology procedures.
However, since numerous studies conducted in the past have demonstrated that skeletal characteristics differ in each population and have emphasized the need for population-specific osteometric standards for sex determination, the present study, also, paves way for further studies to be conducted on more diverse populations to establish population-specific osteometric standards and deriving appropriate regression equations taking into consideration numerous factors, including the various socioenvironmental factors, for example, nutrition, food, and climate; pathologies influencing the development and thus, the appearance of bones and other factors which might influence the growth patterns to come to valid conclusions.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]
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