Examination of new parameters for sex determination of mandible using Japanese computer tomography data

Gender Determination Through Mandibular Features on Orthopantomograms: A Preliminary Study

Introduction Determination of gender can be highly accurate with a complete adult skeleton, but in scenarios like mass disasters, only fragmented bones might be available. In such cases, identifying gender relies significantly on which parts of the skeleton are found. The mandible is a notably distinct bone in the skull and can be key in determining gender, especially when the entire skull is not available. The mandibular features provide clues that can help forensic experts determine the gender of an individual. Aim of the study This preliminary study aimed to determine the gender of an individual using mandibular parameters such as coronoid ramus height, condylar ramus height, projective ramus, minimum ramus breadth, and maximum ramus breadth. The objectives of this study were to (i) determine the gender of an individual using various mandibular parameters, (ii) evaluate the effectiveness of these mandibular parameters in distinguishing between male and female individuals, and (iii) establish a reliable method for gender identification based on the measured mandibular parameters. Materials and methods Since it was a preliminary study, the sample size calculation was done using G*Power software (Version 3.1.9.4; Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany). The sample size was determined to guarantee a 95% statistical power at a significance level (alpha error probability) of 0.05. To ensure sufficient statistical power, a total of 100 samples were included, with a projected sample size of 92. A total of 100 samples, evenly split between 50 males and 50 females aged 20 to 30 years, were analyzed. Orthopantomograms (OPGs) showing pathologies, fractures, developmental disturbances of the mandible, and edentulous mandibles were excluded from the study. Statistical analysis was performed using SPSS for Windows, Version 16.0 (Released 2007; SPSS Inc., Chicago, IL, USA). Additionally, an accuracy test, analysis of variance (ANOVA), multiple regression, and discriminant analysis for gender were performed on individual data. Results In this study, five mandibular parameters were analyzed for gender such as coronoid ramus height, condylar ramus height, projective ramus, minimum ramus breadth, and maximum ramus breadth showed a positive correlation comparatively, and a novel formula was developed.  Conclusion According to the present study, panoramic radiography can be considered a valuable tool in sex determination (with an accuracy of 90%), and all parameters of the mandible exhibited sexual dimorphism, showing they are reliable parameters with a total accuracy of 90%. However, coronoid ramus height, projective ramus, and maximum ramus breadth played a significant role in identifying gender in this particular study.

Evaluation of Sexual Dimorphism Using Condylar and Coronoid Mandibular Parameters in Orthopantomograms: A Pilot Study

Background Gender determination is critical to forensic science and medico-legal applications. Given that it is the most dimorphic bone in the skull and is frequently found intact, the mandibular bone may be extremely important in determining gender. Orthopantomograms (OPGs) are quite helpful in accurately estimating age and sex in this regard. It is a laborious task for forensics to determine the gender of victims of mass casualties, natural disasters, and severely dismembered bodies. The mandible, which is susceptible to development spurts, has a high degree of accuracy for determining sex. Aim  This study aims to evaluate the potential use of coronoid height and condylar height as reliable anatomical markers for determining gender. Materials and methods In this study, 100 samples were used as study samples, 50 of which were male and 50 of which were female, in the age group of 20-30 years. The OPGs were obtained using a Planmeca Promax Scara 3 Digital OPG Machine (Planmeca, Helsinki, Finland), with settings of 70 kVp, 8 mA for 0.9 seconds, ensuring a 1:1 ratio. The images were then transferred to Planmeca Romexis® Viewer Software, Version 6.0 (Planmeca Oy, Helsinki, Finland) for measurement recording. Results Descriptive statistical analysis was done for this study and discriminant analysis was also done to create a population-specific formula. Results showed that the standard mean error for males concerning condylar height was 2.3 and coronoid height was 0.7. The standard mean error for females by condylar height was 1.6 and coronoid height was 0.6. The p-value was significant for coronoid height in both males and females. The p-value was not clinically significant for condylar height in both males and females. Conclusion The study's findings indicate that a larger mandibular angle is advantageous for gender assessment and helps with gender dimorphism. Out of both the parameters evaluated, coronoid height has shown statistical significance in both males and females. Hence, the study concludes that the parameter, coronoid height can be utilized to assess the gender of an individual.

Quantifying Sexual Dimorphism by Analyzing Ramus Flexure and Bigonial Width in Orthopantomography

Introduction The mandible constitutes one of the skull's largest and strongest bones. Growth spurts can influence it, and it has a variety of dimorphic traits that can be used to identify sex. In addition to observing, comparing, and evaluating the potential for mandibular ramus flexure and bigonial breadth to discriminate between sexes using digital orthopantomograms (OPG), a retrospective study was conducted to examine the validity of this method for sex estimation in the Indian population. Aim and objective This study aims to quantify sexual dimorphism by analyzing two mandibular parameters, the ramus flexure and the bigonial width, using orthopantomography (OPG). The objective is to determine the accuracy of sex determination using the ramus flexure and bigonial width. Materials and methods A total of 500 OPG images (250 males and 250 females) were analyzed using the Planmeca software (Helsinki, Finland). The ramus flexure was measured as the angle formed between the tangent to the inferior border of the mandible and the tangent to the posterior border of the ramus. The bigonial width was measured as the distance between the left and right gonion points. A statistical analysis was performed to assess sexual dimorphism and determine the accuracy of sex determination using these parameters. The study employed descriptive statistics, such as means and standard deviations, and an independent t-test to determine the significance of the characteristics in relation to males and females. Results The mean bigonial width for females was 193.3068 mm (SD = 13.51669 mm) and for males was 217.6308 mm (SD = 10.87453 mm), with a statistically significant difference (p = 0.000). The 95% confidence interval for the difference in the bigonial width between males and females was between -49.97173 mm and -43.93787 mm. For the ramus flexure, the mean was 0.0000 for both males and females (SD = 0.00000), with a significant difference between males and females (p = 0.003). The 95% confidence interval for the difference in the ramus flexure between males and females was between -0.59543 and -0.12457. Conclusion The results indicated significant sexual dimorphism in both the ramus flexure and bigonial width. This study demonstrated that the ramus flexure and bigonial width, measured using orthopantomography (OPG), exhibited significant sexual dimorphism. The analysis of these mandibular parameters provided valuable information for sex determination in forensic and anthropological contexts.

Role of Mandibular Parameters in Gender Determination: A Systematic Review and Meta-Analysis

Forensic anthropology and forensic medicine both have been fascinating fields that deal with mandibular characteristics and sex determination. Researchers may determine an individual's biological sex with amazing precision by examining the size, shape, and proportions of the mandible. This information is useful for anthropological studies and criminal investigations. This systematic review aims to evaluate the consistency and validity of using mandibles as a method for gender determination across different populations. A systematic search was conducted in PubMed, Web of Science, and Scopus databases. Further, a manual search was carried out to find additional studies. Mandibular parameters and other relevant data about research were extracted from the included studies. Random effects meta-analysis was carried out for four parameters. A total of nine studies were included in the systematic review out of 76 initial search results. All studies were in vitro. Nine studies were included in the qualitative analysis, whereas only seven studies were included in the meta-analysis. A total of 2385 individuals (1193 male and 1192 female) were evaluated in the included studies. The parameters assessed were as follows: minimum ramus breadth (MiRB), maximum ramus breadth (MaRB), projective ramus height (PRH), bigonial width (BGW), gonial angle (GA), and antegonial angle (AGA). Meta-analysis was conducted for four parameters out of six. For the two parameters, meta-analysis was not conducted as only one study was evaluated. Meta-analyses of PRH obtained a high degree of heterogeneity (99%), mean difference (MD) of 4.06 mm, and p-value of p=0.09. Meta-analysis of BGW obtained 93% heterogeneity, MD of 9.03 mm, and p=0.0007. Meta-analysis of GA showed 99% heterogeneity, MD of 3.44 mm, and p=0.66. Meta-analysis of AGA obtained a low heterogeneity of 30%, MD of -0.77 mm, and p=0.23. The parameter, BGW, can be considered a useful tool in identifying sex. The parameters, PRH, GA, and AGA, cannot be preferred as a reliable tool in identifying the sex of an individual in forensic contexts.

Are computed tomography images of the mandible useful in age and sex determination? A forensic science meta-analysis

OBJECTIVES

This meta-analysis addresses the use of mandibular computed tomography (CT) scans for age and/or sex determination in forensic science.

METHODS

Six databases were searched until June 2023, using the keyword "mandible" combined with keywords related to "multislice computed tomography" (MCT) or "cone-beam computed tomography" (CBCT) and keywords related to "skeletal age determination" or "sex determination analysis."

MAIN RESULTS

Among the 23 studies included, 11 used MCT and 12 used CBCT to perform forensic assessments. Age determination was the aim of a single study, sex and agedeterminations were the objective of five studies, and the other studies investigated the determination of sex only. Metaanalysis could be performed only for sex determination.

CONCLUSIONS

Mandible measurements are useful in sex determination, as the bicondylar and bigonial breadth are larger in males than in females. For the mandible angle, the meta-analysis results confirm sex dimorphism in CBCT scans but not in MCT scans. For age estimation, further studies are needed to prove that the mandible hole is a reliable parameter for age estimation. PROSPERO registration number: CRD42021260967.

Analyzing Mandibular Characteristics for Age and Gender Variation Through Digital Radiographic Techniques: A Retrospective Study

Background Forensic odontology has emerged as a crucial method for identifying skeletal or dental remains. Due to the restricted accuracy of current techniques for estimating age at death, researchers have endeavored to illustrate age-related alterations in dental hard tissues. Bone remodeling constitutes an ongoing and intricate process throughout our lifespan. It is believed that morphological changes in the mandible during an individual's lifetime are influenced by both dental condition and the individual's age. Objectives This study aims to evaluate the efficacy of mandibular parameters such as projective ramus height (PRH), maximum ramus breadth (MaRB), bigonial width (BGW), antegonial depth (Ant.D), and antegonial angle (Ant.A), as a gender-determining tool and compare and analyze the mandibular parameter measurements using digital orthopantomography. Methodology In this study, the total number of samples used was 500 out of which 250 were males and 250 were females. Planmeca software (Version 6.0, Planmeca Romexis, Charlotte, NC) was used and the accuracy test, analysis of variance (ANOVA), multiple regression, and discriminant analysis for gender were performed using SPSS for Windows, Version 16.0 (SPSS Inc., Chicago, IL). Results For age estimation, the least standard error of 0.008 was observed for BGW. A maximum standard error of 0.230 was observed for Ant.D. For sex determination, the coefficient function was positive for PRH, BGW, and Ant.A, with values of 0.202, 0.805, and 0.052, respectively. Ant.D and MaRB both exhibited negative values of -0.204 and -0.379, respectively.  Conclusions Out of all the parameters assessed, BGW is the most preferred parameter for age estimation and Ant.A can be preferred for sex estimation. Age and gender can be estimated using the two parameters in the Indian population.

Objective evaluation of tooth carving using homologous models

PURPOSE/OBJECTIVES

Tooth carvings are evaluated subjectively. However, subjective evaluations are associated with low intra- and inter-evaluator reliability in providing feedback for the fabrication of better tooth carvings. Therefore, this study aimed to analyze the relationship between subjective evaluation and the morphological characteristics of tooth carvings and their morphological characteristics using the feedback method in the low-scoring group.

METHODS

Between April 2013 and September 2021, 120 maxillary left first molar carvings fabricated by undergraduate students were subjectively evaluated by an experienced instructor using a five-point scale. The tooth carvings were scanned to obtain three-dimensional shape data and divided into two groups, the high- and low-scoring groups, for principal component analysis. Homologous models with dimensions matching those of the average model were created, and principal component analysis was performed to evaluate the morphological characteristics of the tooth.

RESULTS

Principal component analysis indicated that an objective evaluation was possible using homologous model. On increasing the subjective evaluation, the occlusal inclination angle and the cervical region of the tooth became steeper, and the shape of the occlusal surface resembled a parallelogram. In addition, large morphological differences were observed in the position of the cervical region of the tooth, height of contour, and shape of the occlusal surface in the low-scoring group, whereas no such difference was observed in the high-scoring group.

CONCLUSION

Objective evaluation of tooth carving was possible using homologous model. The evaluation of tooth morphological characteristics could be effective in providing feedback to undergraduate students.

Forensic Gender Prediction by Using Mandibular Morphometric Indices: A Panoramic Radiograph Study

Aim and objective This study aims to assess the accuracy of gender estimation using gonial and antegonial angles and determine the gender of the given samples using gonial and antegonial angles. Introduction An essential component of the human skull, the mandible, exhibits sexual dimorphism, making it a valuable tool in forensic and anthropological investigations for detecting sex. This procedure can be especially difficult in situations where there are large numbers of casualties, natural disasters, or widely dispersed remains. The mandible is an accurate indicator of age and sex because it responds to patterns of growth. Sex determination through the gonial angle and antegonial angle involves analyzing the angles formed by the lower jaw bone in individuals. Examining these angles contributed to remarkable accuracy. Materials and methods A total of 500 samples, 250 male and 250 female panoramic radiographs, were carefully chosen for the study. The chosen samples ranged in age from 20 to 30 years. Orthophantomograms were measured in Planmeca software (Planmeca Romexis®, Version 6.0, USA INC.) and the descriptive statistics (paired t-test) were performed in SPSS Statistics version 16.0 (SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc.). Results Gonial angle for males obtained the highest value of 127.27±5.29, followed by females at 127.08±5.18. This was followed by the antegonial angle for males of 10.74±3.14, and the least value was obtained by females of 10.67±3.30. The p-value for the gonial angle showed no statistical significance for males or females (p=0.679). Antegonial angle showed statistical significance in both males (p=0.008) and females (p=0.001). Conclusion Among both the parameters considered, the antegonial angle showed significance in determining the gender of the given samples. Hence, to assess the accuracy of gender estimation, the antegonial angle can be used as a parameter.

Estimation of missing mandible from the skull using postmortem CT images

Skeletal remains often have missing mandibles owing to the environment in which the corpse was placed or damage caused by an animal. Loss of the mandible reduces the accuracy of skull identification. Although several studies have validated methods for estimating mandibular morphology from conventional anthropological measurements using skull specimens, there are no reports using three-dimensional computed tomography (3DCT) images. Here, we examined methods for establishing the mandibular morphology from the remaining skulls using postmortem computed tomography (PMCT) images. We used PMCT images from 200 Japanese subjects as samples. After verifying the morphological correlation between the cranium and mandible, we created and validated estimation models using multiple regression analysis (stepwise method) for seven sites that were necessary for understanding the morphology of the mandible. Among the regression models, the estimated model for bicondylar breadth had the highest coefficient of determination (adjR2 = 0.53). We verified the accuracy of the model on a sample independent from the specimen used to create the estimation model and found that the formulated model of bicondylar breadth had good estimation accuracy, with a high correlation coefficient between the measured and predicted values of 0.82 and a mean absolute error of 3.582 mm, indicating that the model had good estimation accuracy. Here, we established a novel method for estimating the missing mandibular morphology based on PMCT data from the Japanese population. Our estimation model can help determine the missing mandibular morphology in a cranium remnant.

Size and shape of human mandible: Sex differences and influence of age on sex estimation accuracy

The degree of sexual dimorphism expressed by human bones is of primary importance for the development of accurate methods for sex estimation. The objective of the present study was to investigate sex differences in shape and size of the mandible using geometric morphometric methods. The study also aimed to examine the impact of age on the sex classification ability of the size and shape of the mandible. Computed tomography images of 190 Bulgarians (98 males and 92 females) were used in the study. Polygonal surface models of the skulls were generated and used for digitizing 45 landmarks located on the mandible. The raw three-dimensional coordinates of the landmarks were processed via generalized Procrustes superimposition. The sex differences in mandibular size and shape were evaluated for statistical significance. Multivariate regression was applied for correction of the allometric effect. Principal component analysis, discriminant analysis, and canonical variate analysis were also used in the study. Mandibular size differed significantly between males and females and achieved a sex classification accuracy of 87%. The significance of the sex differences in mandibular shape depended on the type of shape variables used in the analysis. The shape variables provided different classification accuracy: 78% using the Procrustes coordinates and 53% using the regression residuals. The male and female mandibles differed significantly in size and shape, including the allometric component. Mandibular size is a more effective sex indicator than shape. Age has an ambiguous effect on the classification accuracy of the size and shape variables of the mandible.

Application of the Homologous Modeling Technique for Precision Medicine in the Field of Oral and Maxillofacial Surgery

In the field of oral and maxillofacial surgery, establishment of a new method for predicting morphology is desirable. Therefore, the purpose of the present study was to establish a new method for predicting the original shape of a mandibular defect site using the homologous modeling technique. This study used data from 44 patients who underwent computed tomography in the Department of Oral Surgery at Osaka Medical College. Two types of homologous models were constructed: total mandible (TM) and half mandible (HM). Principal component analysis (PCA) was performed using point cloud data of the homologous model M and homologous model HM, and a multiple regression equation was created using the PC value of TM as the object variable and PC value of HM as the explanatory variable. The predicted PC (M) was created from PC (HM) using a regression formula, back-calculated from point cloud data from PC (M), to create the predicted mandible model. Finally, the original image (TC-M) and estimated mandible were superposed and examined. The mean absolute error between the predicted mandible and actual mandible was 1.04 ± 1.35 mm. We believe that this method will be applicable in actual clinical practice.

Cranial and Odontological Methods for Sex Estimation—A Scoping Review

The estimation of sex from osteological and dental records has long been an interdisciplinary field of dentistry, forensic medicine and anthropology alike, as it concerns all the above mentioned specialties. The aim of this article is to review the current literature regarding methods used for sex estimation based on the skull and the teeth, covering articles published between January 2015 and July 2022. New methods and new approaches to old methods are constantly emerging in this field, therefore resulting in the need to summarize the large amount of data available. Morphometric, morphologic and biochemical analysis were reviewed in living populations, autopsy cases and archaeological records. The cranial and odontological sex estimation methods are highly population-specific and there is a great need for these methods to be applied to and verified on more populations. Except for DNA analysis, which has a prediction accuracy of 100%, there is no other single method that can achieve such accuracy in predicting sex from cranial or odontological records.

A three-dimensional statistical shape model of the growing mandible

Mandibular growth and morphology are important topics in the field of oral and maxillofacial surgery. For diagnostic and planning purposes, a normative database or statistical shape model of the growing mandible can be of great benefit. A collection of 874 cadaveric children’s mandibles with dental age between 1 and 12 years old were digitized using computed tomography scanning and reconstructed to three-dimensional models. Point correspondence was achieved using iterative closest point and coherent point drift algorithms. Principal component analysis (PCA) was applied to find the main modes of variation in the data set. The average mandible was presented, along with the first ten PCA modes. The first mode explained 78% of the total variance; combining the first ten modes accumulated to 95% of the total variance. The first mode was strongly correlated with age and hence, with natural growth. This is the largest study on three-dimensional mandibular shape and development conducted thus far. The main limitation is that the samples lack information such as gender and cause of death. Clinical application of the model first requires validation with contemporary samples.