|Year : 2022 | Volume
| Issue : 2 | Page : 218-222
Introduction of a new parameter 'Mastoid to Gonion Height' and its comparative evaluation with established pa cephalometric parameters in sex determination: An analytical study
Ramhari Sathawane1, Samiksha Tripathi2, Vidyarjan Sukhadeve1
1 Department of Oral Medicine and Radiology, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra, India
2 Arihant Dental Clinic, 1st Floor, IDBI Bank Building, Opp. Mahawar Dharmshala, Sihawa Chowk, Dhamtari, Chhattisgarh, India
|Date of Submission||12-Jan-2022|
|Date of Decision||22-Mar-2022|
|Date of Acceptance||07-May-2022|
|Date of Web Publication||22-Jun-2022|
Department of Oral Medicine and Radiology, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Skeletal remains have a vital role in the differentiation of sex in forensic studies. Skull is the second most sexed skeleton after the pelvis. PA cephalogram is more precise and provides numerous anatomic points and planes in the frontal profile for comparison. Aim: To introduce a new parameter 'Mastoid to Gonion height,' and compare its accuracy with established PA cephalometric parameters in sex determination using discriminant functions. Materials and Methods: A hundred males and females each aged 25 to 60 years were included. A total of eight planes were constructed on PA cephalograms and measured. The data were analyzed using discriminant analysis. Results: The linear measurements were found greater in males than females. Among the studied parameters, Bizygomatic width and Mastoid to Gonion height had a high sex discriminating ability. The discriminant function (DF) equation correctly predicted the gender in 88.5% of subjects. Conclusion: The new parameter “Mastoid to Gonion” height has been successfully introduced. It is found to be the second-best strong predictor parameter and can be used singly for sex determination. The parameter Bi-zygomatic width also contributed most significantly and can be used singly. The DF equation is proposed to predict new cases.
Keywords: Discriminant function equation, forensic studies, Mastoid to Gonion height, PA cephalograms, sex determination
|How to cite this article:|
Sathawane R, Tripathi S, Sukhadeve V. Introduction of a new parameter 'Mastoid to Gonion Height' and its comparative evaluation with established pa cephalometric parameters in sex determination: An analytical study. J Indian Acad Oral Med Radiol 2022;34:218-22
|How to cite this URL:|
Sathawane R, Tripathi S, Sukhadeve V. Introduction of a new parameter 'Mastoid to Gonion Height' and its comparative evaluation with established pa cephalometric parameters in sex determination: An analytical study. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Jul 1];34:218-22. Available from: https://www.jiaomr.in/text.asp?2022/34/2/218/347919
| Introduction|| |
Human identification is one of the most vital responsibilities of Forensic Medicine. It holds social, economic, and legal repercussions.,,, Non-mutilated remains do not pose many difficulties, but the challenge lies in identifying mutilated body parts. Skull is the second most commonly sexed skeleton after the pelvis.
Postero-anterior (PA) cephalogram does enhance the accuracy of sex determination as it not only provides morphological details of the skull but displays multiple points like facial height and width in the frontal profile for comparison. Since the skeletal development is influenced by various environmental factors, it is necessary to have population-specific studies.
Hence, the present study introduced a new parameter, 'Mastoid to Gonion height,' and compared its accuracy with established parameters in sex determination using discriminant functions.
| Material and Methods|| |
In the present prospective analytical study, 200 individuals who reported to the Department of Oral Medicine and Radiology over 18 months were selected by convenient random sampling. The study included normal individuals in the age range of 25 to 60 years. The individuals with facial asymmetry, developmental/osseous skull disorders, skeletal malocclusion, history of craniofacial trauma, history and/or clinical features suggestive of hereditary, endocrinal, and nutritional disturbance, individuals undergoing or having undergone any orthodontic or orthognathic treatment were excluded from the study. IEC approved the protocol of the study (No. CDCRI/PG/Syn/OMR-3/2015). Approval from the ethics committee is obtained. Approval date- 10/02/2015. Based on the findings of a study carried out by Madadin et al., the sample size was derived considering the expected predictive accuracy of sex determination with 9% relative precision and 95% confidence interval as follows:
Z2 (1-α) = 1.96 for 5% level of significance or 95% confidence interval
P = anticipated predictive accuracy = 0.714 (71.4%)
d = relative precision = (0.09 × 0.714) = 0.064
Included study sample size = 200 subjects.
Ethical principles as per the Helsinki declaration 2000 and ethical norms for human experimentation were followed. After obtaining the written informed consent, detailed case history & thorough clinical examination was made.
Digital PA cephalograms were taken on a SIRONA ORTHOPHOS XG5 DS X-ray machine and viewed using Sidexis software. Planes were constructed on each radiograph for predetermined landmarks and measured using a length tool. Parameters Bi-latero-orbitale width, Mastoid length, Mastoid to Gonion height, Bi-gonial width, Bi-maxillary width, Bi-zygomatic width, Bi-condylar width, and Maximum cranial width were evaluated [Table 1] and [Figure 1].
|Figure 1: PA Cephalogram showing the recorded parameters. (a) Bi-lateral orbital width (b) Mastoid length (c) Mastoid to Gonion height (d) Bigonial width (e) Bimaxillary width (f) Bizygomatic width (g) Bicondylar width (h) Maximum cranial width|
Click here to view
Statistical analysis was performed using the SPSS 15.0 ver. 2.11.1 software. Descriptive statistics were done for all the parameters providing mean and standard deviations. The values were compared using Student's t-test for any significant differences between the sexes. The Chi-Square test was used to find the significance of study parameters on a categorical scale between the groups. DF analysis was used to determine which parameter(s) discriminate between the two groups.
| Results|| |
All the subjects were divided into four age subgroups. There were 41 females and 64 males in the age group of 25-34 years, 34 females and 13 males in 35-44 years, 21 females and 16 males in 45-54 years, and 4 females and 7 males in 55-60 years [Table 2].
It was observed that measurements of all the parameters were greater in males than females. Multivariate ANOVA was used for each independent parameter, and the results indicate that the difference was highly significant (P = 0.001) [Table 3].
First 1 canonical linear DF was used as there were only two (male and female) discriminating variables. The given value of 1.028 indicates a strong discriminating ability of function (Eigen value >1 suggests a strong function). The percentage of variance and cumulative percentage account for the 100% discriminating ability of the parameters. The canonical correlation of 0.712 signifies a high discriminating function (1.00 is perfect). The observed Wilks Lambda value of 0.493 indicates that it has a very high discriminating ability (Chi sq. = 137.176, P = 0.001).
The standardized Canonical DF coefficient for Bi-zygomatic width is highest (0.550), followed by mastoid to gonion height (0.461) and mastoid length (0.447), indicating that they have a high sex discriminating ability. The coefficients for parameters bi-gonial width (0.289), bi-condylar width (0.176), and bi-latero orbitale width (0.141) indicate that they have a low discriminating ability. The coefficients for bi-maxillary width and maximum cranial width (both with -ve signs) indicate that they have the poorest discriminating ability [Table 4].
In the present study, the means for each group are equal in absolute value but have opposite signs (male = +1.009 and female = -1.009). It indicates that the means are completely well apart and signifies that the discriminant function discriminates against the sexes.
Unstandardized Coefficients are used to develop the DF equation to classify new cases.
DF = (0.029 × Bi-latero orbitale width) + (0.109 × Mastoid length) + (0.074 × Mastoid to Gonion height) + (0.036 × Bi-gonial width) + (-0.020 × Bi-maxillary width) + (0.081 × Bi-zygomatic width) + (0.033 × Bi-condylar width) + (-0.021 × Maximum cranial width) + (−21.361 (Constant)) [Table 5].
On substituting values of parameters from an unknown individual in this DF equation, if the value is closer to -1.009, the individual is a female. If it is closer to +1.009, then the individual is a male.
Sex discrimination accuracy on cross-validation shows that 94% of females and 83% of males were predicted correctly, whereas 6% of females in the female group and 17% of males in the male group were predicted incorrectly, with overall predicted discrimination accuracy 88.5% [Table 6].
| Discussion|| |
Establishing the identity of an individual is essential in any medico-legal procedure. Thus, dimorphic characteristics of the skull play an important role in discriminating sex., The mandible is also the commonly found intact bone. It can be sexed as it expresses strong sexual dimorphism.
A literature review revealed very few studies that used conventional PA cephalograms,, and digital PA cephalograms, for sex determination. The present study evaluated eight parameters, including a new parameter mastoid to gonion height using digital PA cephalograms. Examination of a skull using DF is a required method used to sort out people into two or more distinct groups concerning sets/measurements.
The study subjects were in the age group of 25–60 years. The lower limit was set at 25 because the growth of the cranio-mandibular region is complete by this age. The higher limit was based on Krogman's proposition that the cranio-mandibular parameters are affected by the changes in senility above 60. Determination of sex below and above this age range may show excessive variations. The study subjects were divided into four age subgroups. This subdivision did not show a significant difference in the measurements of the parameters. A similar observation was reported by Patil and Mody. Therefore, we strongly propose that age-wise subdivision is not required in such studies.
In the present study, only linear measurements are used because angular measurements and ratios require an intact skull which is not always possible in the forensic scenario. The parameters bi-zygomatic width, bi-maxillary width, bi-gonial width, bi-condylar width, mastoid length, and maximum cranial width are used as they were found to have greater accuracy by Roger, and Naikmasur et al. The parameters bi-latero-orbitale width and bi-maxillary width are used in the field of Orthodontics.,, Still, none of them were examined to determine sex. They are evaluated for their accuracy in the determination of sex. There is no literature examining the parameter 'Mastoid to Gonion height.' This new parameter is introduced and evaluated for the determination of sex.
The multivariate descriptive statistics show that males exhibit significantly greater mean linear measurements than females. All the parameters are good discriminators of sex (p < 0.001). Patil and Mody, Naikmasur et al., Marianayagam and Vallathan, Soman et al., Belaldavar et al., Basyouni, Ngeow and Aljunid observed greater measurements in males than females in their studies which had different aims, methodology, and different parameters in different populations.
Standardized coefficients for all the parameters showed that Bizygomatic width (0.550) is the strongest predictor parameter to determine sex, followed by Mastoid to Gonion height (0.461) and Mastoid length (0.447). They can be used singly for the determination of sex. Other parameters are found to have weak sex discriminating ability. The observations of the present study are in agreement with Roger and Naikmasur et al. The present study evaluated three new parameters. However, only one new parameter, 'Mastoid to Gonion height,' used for the first time, is found to be the second-best parameter to determine sex singly. The other parameters, bi-latero-orbitale width and bi-maxillary width, are invalid.
In the present study, the overall accuracy of sex discrimination is 88.5%. This is higher than the values observed by Naikmasur et al. (88.2% and 81.5% accuracy in different populations), Madadin et al. (71.4%), Sprowl (87%), Allam and Allam (85%), Kanchan et al. (80%), Ramamoorthy et al. (77.1%), and Sumati et al. (76.6%).
The result of the present study validates the existence of significant sexual dimorphism between the sexes and provides PA cephalometric values for use in the Indian population. The DF equation is derived to predict new cases.
| Conclusions|| |
- 'Mastoid to Gonion height' has been successfully introduced. It is the second-best predictor parameter that can be used singly as a definite parameter for sex determination.
- Bi-zygomatic width and Mastoid length also contributed most significantly to sexual dimorphism.
- Gender has been identified correctly in 88.5% of cases using DF.
- The DF equation is proposed to classify new cases.
The present study's findings confirm the role of all PA cephalometric parameters in identifying sex. DF equation to classify new cases is derived using values of all parameters and proposed for use in the Indian population. Since the bi-zygomatic width and mastoid to gonion height were the strongest predictors, we recommend singly using the new parameter 'Mastoid to Gonion height' to determine sex on different geographic populations. Using the new parameter 'Mastoid to Gonion height' and the derived DF equation would greatly help forensic experts in criminal jurisprudence.
Declaration of patient consent
The authors certify that they have obtained all patient's consent forms. Patients have given their images and consent for clinical information reported in the journal. Patients understand that their names will not be published and due efforts will be made to conceal their identity.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]