| Abstract|| |
Introduction: Mandible undergoes age- and sex-related structural changes similar to other bones of the body. Thus, morphometric analysis of the mandible helps in age and sex determination. Aim: To investigate the influence of age and sex on the mandible by measuring three parameters, i.e. gonial angle, ramus height and bigonial width. Materials and Methods: A retrospective radiomorphometric analysis was conducted in the department of Oral Medicine and Radiology. A total of 300 panoramic radiographs (150 males and 150 females) equally distributed in six study groups according to the age were analysed. The measurements were performed using DIGORA 2.8 software for Windows. The acquired data was statistically analysed by one way ANOVA test and Student's t-test using SPSS (v. 19.0). Results: Statistically significant differences according to age were found in gonial angle dimensions. Ramus height and bigonial width did not demonstrate statistically significant co-relation with age. According to sex, all the three study parameters showed statistically highly significant differences. Conclusion: The morphometric analysis of the mandible is a useful tool for age estimation and sex determination.
Keywords: Dental, mandible, morphometry, panoramic, radiography
|How to cite this article:|
Shah PH, Venkatesh R, More CB, Vaishnavee V. Age- and sex-related mandibular dimensional changes: A radiomorphometric analysis on panoramic radiographs. Indian J Dent Res 2020;31:113-7
|How to cite this URL:|
Shah PH, Venkatesh R, More CB, Vaishnavee V. Age- and sex-related mandibular dimensional changes: A radiomorphometric analysis on panoramic radiographs. Indian J Dent Res [serial online] 2020 [cited 2021 May 11];31:113-7. Available from: https://www.ijdr.in/text.asp?2020/31/1/113/281807
| Introduction|| |
The mandible is the largest and most rigid bone in the facial skeleton. It undergoes remodelling and morphological alterations throughout the lifetime of an individual. Morphological changes of the mandible are mainly influenced by the age of the individual and occlusal status. Apart from that, the contractile activity of the masticatory muscles also influence the dimensions of the mandible. Studies have demonstrated age-related changes using various parameters such as gonial angle, bigonial width and mandibular ramus height and breadth, mandibular body length, bicondylar width as representative of these alterations in mandible.,
Gonial region, antegonial region, ramus and condyle of the mandible are the most commonly influenced areas by the age-related changes. Function and shape of the muscles of mastication also influence their shape. As the masseter and medial pterygoid muscles have their insertions in gonial region, they are mainly associated with these changes. With advancement of age, the contractile activity and structural density of these muscles decrease. These changes result in alteration of the dimensions of the gonial angle, which in turn leads to changes in bigonial width and also affects the height of the mandibular ramus. Furthermore, differences in the dimensions of these parameters according to the gender are also demonstrated by some studies.,
Although there is a mention in the literature about the influence of age and gender on gonial region, the findings of various studies are inconsistent. Some studies show widening of the gonial angle with age and with female gender but other studies do not confirm the same., Similarly, the age-related alterations of bigonial width and ramus height are demonstrated by some studies but the other studies show different results. Therefore, the present study aims to determine the association of the dimensions of these three parameters with the age and gender of an individual with a larger sample size.
| Materials and Methods|| |
The present retrospective radiomorphometric analysis was performed in the Department of Oral Medicine and Radiology of a dental college after obtaining the permission from the Institutional Ethics Committee (SVIEC/ON/DENT/SRP/16013 dtd. 22/01/2016). The panoramic radiographs of the patients reported from June 2015 to December 2015 were obtained from the archives of the department for analysis.
A total of 300 panoramic radiographs obtained from the archives of the department were selected based on the pre-determined criteria. The panoramic radiographs with good contrast and resolution covering the gonial angle and ramus region bilaterally were included in the study. The panoramic radiographs showing image distortion or any pathosis in the mandible were excluded from the study. The selected radiographs were equally divided into six study groups depending upon the age range, i.e. 10–19, 20–29, 30–39, 40–49, 50–59 and 60–69 years. All these radiographs were imaged using Kodak 8000C digital panoramic and cephalometric imaging system.
The radiographs were subjected to measurements of right and left gonial angles, mandibular ramus height and bigonial width by using DIGORA 2.8 software for Windows. The method employed for measuring the said parameters was according to the study conducted by Shamout et al. The intersection of the tangent line traced to the lower border of the mandible and the line traced to the posterior border of the ramus was measured as gonial angle. The ramus height was measured as the length of a line extending from the most superior lateral point to the most inferior lateral point on the ramus tangent. The bigonial width was measured as a linear distance between the right and left gonia [Figure 1] and [Figure 2].
The collected data was analysed using a statistical software package International Business Machines Corporation, Statistical Package for the Social Sciences version 19.0 (IBM SPSS v. 19.0). Co-relation of the study parameters with age was analysed by one-way ANOVA test and assessment of co-relation with sex was done by applying Student's t-test. The level of significance was set at P < 0.05.
| Results|| |
The 300 panoramic radiographs belonging to 150 males and 150 females were equally divided into six study groups according to age, i.e. 50 radiographs per group. There was equal sex distribution in each study group, i.e. 25 radiographs of male patients and 25 radiographs of female patients [Table 1].
The mean values of the right and left gonial angles were maximum in 10–19 years study group (124.30 and 123.760) and minimum in the 40–49 years study group (119.130 and 119.90). Statistically significant differences according to age were found in the right (P < 0.001) and left (P = 0.026) gonial angle dimensions [Table 2]. Ramus height and bigonial width were found to be increased with age. The differences were not statistically significant (P > 0.05), though [Table 3] and [Table 4].
|Table 2: Gonial angle dimensions in different age groups (One way ANOVA)|
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The mean values of the right and left gonial angles were higher in females, while the ramus height and bigonial width dimensions were greater in males. According to sex, all the three study parameters showed statistically highly significant differences. (P < 0.001) [Table 5].
| Discussion|| |
The influence of the muscular attachments on the size and shape of the mandible is observed from the time of development of the mandible. The attachments of various muscles on the mandible and their stretching effects are essential for normal growth and development of the mandible. After this period, the constant forces applied by these muscles and the age-related alterations in their strength have major association with the morphological alteration of the mandible., These mechanical forces and age-related alterations in these forces form the basis of the concept of age-related morphological alterations of the mandible. As the overall masticatory forces are greater in males as compared to that in females, there are dimensional variations according to sex also. The average values of these dimensions according to age and sex of the individuals for specific population aid in forensic age and sex determination.
Due to the easy access and low radiation dose, panoramic radiography is a commonly used diagnostic modality to assess osseous changes in the mandible. Panoramic radiographs have good accuracy and reproducibility for linear and angular measurements., The previous morphometric analysis using panoramic radiographs have demonstrated significant results for age- and sex-related alterations in jaw., Moreover, in comparative studies with other imaging modalities, no significant differences were noted in the measurements by panoramic radiographs. In this way, panoramic radiography has become a useful tool in studies that are oriented towards the analysis of the craniofacial complex and also the development process.
The ramus height represents vertical dimensions and the bigonial width represents horizontal dimensions of the mandible. Furthermore, the gonial angle is formed by intersection of a vertical line with an anteroposterior tangent. Thus, the selected measurements represent the mandibular dimensions in all three planes. Many investigators, have studied age and sex alterations in gonial angle with or without other parameters, but a combination of these three dimensions has been studied by very few investigators. Therefore, the present study was designed to determine age- and sex-related changes in the gonial angle, ramus height and bigonial width of the mandible.
In the present study, statistically significant differences (P < 0.05) were noted in the gonial angle dimensions according to the age of the individuals. The dimensions of gonial angles were obtuse in the younger (10–19 years) age group. In the adult age groups (20–29, 30–39 and 40–49 years), they were noted to become acute and in the older age groups (50–59 and 60–69 years), the dimensions were obtuse. From infancy to adulthood, the mandible undergoes various growth and developmental changes and the obtuse gonial angle in infancy and childhood gradually becomes acute during adulthood. As the age advances and progresses to older age group, the age-related decrease in muscular forces and resorption of alveolar process due to tooth loss leads to obtuse gonial angle again., This finding in our study was similar to the studies of Shamout et al., Ghaffari et al., Bhuyan et al. and Moron andGimeno who demonstrated statistically significant difference in the dimensions of gonial angle according to age, whereas in the study of Bathla et al., Rajkumari et al. and Pillay et al. the difference was not statistically significant.
The ramus height and bigonial width were noted to be increased with age in the present study. The differences were not statistically significant, though. Our findings were similar to the study conducted by Bhuyan et al., who also found the differences in the abovementioned parameters statistically not significant. Our findings were in contrast to the findings of Shmout et al. who noticed significant differences in these dimensions.
In our study, gonial angle dimensions were noted to be significantly more in females as compared to that in males (P < 0.001). These findings were similar to Ghaffari et al., Huumonen et al., Moron and Gimeno and Rajkumari et al. but not similar to Shamout et al. and Pillay et al. Pecora et al. have observed that females have downward and backward rotation of the mandible while males have forward rotation of the mandible. This can be a possible explanation for the wider gonial angels in females.
Statistically significant differences in the ramus height and bigonial width were noted according to sex. Both the dimensions were greater in males. This finding was similar to the findings in the studies of Shamout et al., Ghaffari et al., Huumonen et al. and Bhuyan et al. The overall masticatory forces are more in males leading to overall increased dimensions of the mandible.
There were limitations of our study.
In our study, we have not compared the effect of dentition on the morphometric alterations of the mandible. Apart from the influence of muscles, the status of dentition and edentulousness also have an effect on the dimensional variations of the mandible. Future studies should be designed in such a way that the effects of both the factors can be assessed. Another limitation is inherent geometric distortions of panoramic radiography that can be overcome in future studies by using advanced imaging modalities like computed tomography and cone-beam computed tomography and 3D printing.
| Conclusion|| |
The findings of the present study showed significant differences in gonial angle dimensions according to the age of the individual and significant differences in gonial angle, ramus height and bigonial width according to sex. Thus, these dimensions are reliable indicators of age and sex of the individuals. Thereby, the morphometric analysis of the mandible can be a helpful tool in forensic sciences as well as an aid in the studies of growth patterns.
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Conflicts of interest
There are no conflicts of interest.
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Palak H Shah
Department of Oral Medicine and Radiology, K. M. Shah Dental College and Hospital, Sumandeep Vidyapeeth University, Piparia, Vadodara - 391 760, Gujarat
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]