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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 16  |  Issue : 1  |  Page : 97-101

Evaluation of morphological alteration in human mandible: A prospective cross-sectional panoramic radiographic study


1 Department of Oral Medicine and Radiology, Vyas Dental College and Hospital, Jodhpur, Rajasthan, India
2 Department of Oral Medicine and Radiology, MDM Hospital, Jodhpur, Rajasthan, India

Date of Submission21-Aug-2019
Date of Decision20-Nov-2020
Date of Acceptance21-Jan-2021
Date of Web Publication29-Jul-2021

Correspondence Address:
Dr. Ankita Bohra
Department of Oral Medicine and Radiology, Vyas Dental College and Hospital, Jodhpur, Rajasthan
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdmimsu.jdmimsu_126_19

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  Abstract 


Background: The aim of the study is to evaluate the morphological alterations of the mandiblebetween different age groups, gender, and dentition status. Materials and Methods: A total of 1000 patients (500 males and 500 females), panoramic radiographs, were included in the study out of 57,640 patients in the outpatient department for 1 year. The patients were categorized according to age, gender, and dentition status that were assessed. Results: Statistically significant relation was observed between the mean antegonial angle, depth, gonial angle, and mandibular cortical index (MCI) with respect to the age, gender, and dentition status. The value of antegonial angle decreased with age and edentulousness, while antegonial depth increased with age and edentulousness. Females had higher values of antegonial angles as compared to males for antegonial angle, while the opposite is true for antegonial depth. Conclusion: There is an inherent asymmetry in the antegonial regions between the right and left sides. The gonial angle can serve as an adjuvant and additional forensic parameter, which guides for age group assessment and gender identification. MCI can be used as a diagnostic tool for screening patients with or without osteoporotic changes.

Keywords: Antegonial angle, gonial angle, mandibular cortical index


How to cite this article:
Bohra A, Harsh A. Evaluation of morphological alteration in human mandible: A prospective cross-sectional panoramic radiographic study. J Datta Meghe Inst Med Sci Univ 2021;16:97-101

How to cite this URL:
Bohra A, Harsh A. Evaluation of morphological alteration in human mandible: A prospective cross-sectional panoramic radiographic study. J Datta Meghe Inst Med Sci Univ [serial online] 2021 [cited 2021 Sep 23];16:97-101. Available from: http://www.journaldmims.com/text.asp?2021/16/1/97/322593




  Introduction Top


The mandible (from Latin mandibula, “jawbone”) or inferior maxillary bone forms the lower jaw and holds the lower teeth in place.[1] The mandible is the first pharyngeal arch derivative and originates from the neural crest cells that travel ventrally to take their position within the mandibular and maxillary prominences during the 4th week after conception. Interactions between the mandibular ectomesenchyme and the mandibular arch epithelium result in the formation of an osteogenic membrane between days 36 and 38 of development.[2],[3],[4],[5],[6],[7],[8],[9],[10],[11] When the teeth fall, the movement ceases and is responsible for resorption. Resorption is very much greater when the number of adjacent teeth is lost. When all the teeth are lost, the upper and lower gums are used as organs of mastication. This exerts pressure on the bone and is responsible for the disappearance of the bone.[12] Any change in the gonial angle is largely produced by ramus remodeling and is determined by the remodeling direction of the ramus with its condyle. During an individual's life, the morphological changes undergone by the mandible are thought to be influenced by the dental status and age of the patient. Muscle function should preserve the bony structures of the gonial angle and symphyseal regions, irrespective of dental status and age-related remodeling of the mandible.[13],[14]

The gonial angle is thought to increase with age and also widens with the edentulous state. The antegonial depth increases with the advancement of age, while the antegonial angle decreases. Mandibular angle, antegonial angle and depth, cortical density varies in between gender depending on masticatory overloads.[15] This significant decrease in the values of antegonial angle and a significant increase in the values of antegonial depth as the dentition status changed from completely dentulous to partially dentulous and from partially dentulous to completely edentulous state. The cortical width measurements are included under the mandibular cortical width (mandibular cortical index [MCI]). Various factors affecting mandibular cortical width include age, osteoporosis, and insufficient occlusal forces. Changes in mandibular cortical thickness with advancing age and edentulousness represent a secondary adaptation to relatively larger strains due to a reduction in alveolar height and corpus cross-section despite overall reduced muscular and biting loads.[16] The present study using panoramic radiograph will be able to better understand the remodeling of the mandible in age, gender, and dental status. The aim of the study is to evaluate the morphological alterations of the mandible in gonial angle, MCI, antegonial angles, and depths with respect to age, gender, and dentition status.


  Materials and Methods Top


The study was conducted at the Department of Oral Medicine and Radiology, Vyas Dental College and Hospital, Jodhpur, Rajasthan, India, from January 01, 2014, to December 31, 2014. Ethical clearance for the study was obtained from the institutional ethical committee before the start of the study. The purpose of the study was explained to each participant prior to the collection of data and written consent was obtained from all the patients who participated in the study. A total of 1000 patients (500 males and 500 females), panoramic radiographs, were included in the study out of 57,640 patients in the outpatient department for 1 year. The patients were categorized according to age, gender, and dentition status and gonial angle, MCI, antegonial angles, and depths that were measured. The patients were divided based on age into five groups of 200 patients in each group, (100 males and 100 females) with the following age groups: 20–29 years, 30–39 years, 40–49 years, 50–59 years, and ≥60 years.

The dentition was recorded using a simple classification system:

  1. A = Only Anterior teeth missing (till canines)
  2. P = Only Posterior teeth missing (from 1st premolars to molars)
  3. AP = Anterior and posterior teeth missing.
  4. E = Completely edentulous
  5. D = Completely dentulous.


Panoramic radiographs were taken on a Kodak 8000C digital panoramic machine, with exposure parameters being in the range of 65–70 kVp and 8 mA. Digital images were evaluated by a subjective determination of patient positioning, head alignment, film density, and contrast, which were within the reviewer's standard range of quality.

The following radiomorphometric indices were measured using Radiant Dicom image viewer version 1.21 (Poznań, Promienista, Poland) software for each radiograph

  1. Gonial angle: The gonial angle was assessed by tracing a line tangent to the lower border of the mandible and another line tangent to the distal border of the ramus on both sides. The intersection of these lines formed the gonial angle
  2. Antegonial angle: The antegonial angle by tracing two lines parallel to the antegonial region that intersected at the deepest point of the antegonial notch
  3. Antegonial depth: The antegonial depth was measured as the distance along a perpendicular line from the deepest point of the notch concavity to a tangent through the inferior border of the mandible
  4. MCI: According to the classification of Klemetti et al. criteria, MCI is the appearance of the inferior mandibular cortical thickness, which is as follows:


    • C1: The endosteal margin of the cortex is even and sharp on both sides
    • C2: The endosteal margin shows semilunar defects (lacunar resorption) or it seems to form endosteal cortical residues (one to three layers) on one or both sides
    • C3: The cortical layer forms heavy endosteal residues and it is clearly porous.


Exclusion criteria

The following were excluded from the study:

  • Patients with gross facial asymmetry or patients with skeletal malocclusion
  • Patients with various anomalies affecting the craniofacial region and mandible and various systemic and local disorders affecting the growth of the craniofacial region
  • Patients who were undergoing or had undergone any orthognathic surgery
  • Patients who had undergone any other major surgery and/or radiotherapy related to the head and neck
  • Patients with symptoms of temporomandibular joint disorders
  • Patients with any history of facial trauma
  • Only high-quality radiographs were considered for the study. Radiographs with various errors were excluded from the study.


The recorded data were compiled and entered into a spreadsheet computer program (Microsoft Excel 2010) and were then exported to a data editor of SPSS, version 18.0 (IBM, Armonk, New York). Comparison between right and left gonial angle, antegonial angle, antegonial depth, MCI in each age group and gender (t test). Also variation of values of antegonial angle, antegonial depth, gonial angle and MCI within different age groups and dentition status (one way ANOVA). Addition to this correlation between age, gender, dentition status and morphological changes in human mandible by measuring the antegonial angle, antegonial depth and gonial angle MCI using panoramic radiograph (Spearman test) were performed.

Ethical clearance

The Institutional Ethics Committee of Vyas Dental College & Hospital with approval no. VDCH/IEC/23/2013 dated : 9th Nov 2013.


  Results Top


Statistically significant relation was observed between the mean antegonial angle, depth, gonial angle, and MCI with respect to the age, gender, and dentition status. The value of antegonial angle decreased with age and edentulousness, while the antegonial depth increased with age and edentulousness. Females had higher values of antegonial angles as compared to males for antegonial angle, while the opposite is true for antegonial depth [Table 1] and [Table 2]. Statistically significant categories of MCI (C1/55.2%, C2/32.7%, and C3/12.1%) were detected. There was a statistically significant difference in the categories of MCI between men and women. Categories C1 and C3 were more frequently seen in women, while Category C2 was more frequently seen in men. Dental status was significantly different according to the categories of MCI [Table 3]. While comparing the mean values of antegonial angle on the right and left sides, the left side values were more than the right side values in each group. The mean values of gonial angle were more on the right side than the left side in each age group. There was a statistically significant difference in the values of gonial angle and antegonial angle between the age groups (P ≤ 0.05).
Table 1: Morphological changes in human mandible by measuring the antegonial angle, antegonial depth, and gonial angle according to the age, gender, and dentition status using panoramic radiograph

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Table 2: Morphological changes in human mandible by measuring the mandibular cortical index according to the age, gender, and dentition status using panoramic radiograph

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Table 3: Comparison between right and left gonial angle, antegonial angle, and antegonial depth in each age group (t-test)

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The mean values of the gonial angle increased with respect to edentulism. The values were maximum for edentulous individuals on the right side and minimum for dentulous individuals on the left side. The results were statistically significant for both antegonial and gonial angles. The mean values of antegonial angle decreased with respect to the dentition. On comparing dentition status and gender, the values of antegonial angle were more in dentate female individuals on the left side, while they were least in edentulous males on the right side. The mean value of the gonial angle increased with dentition status. On comparing dentition status and gender, the values of gonial angle were maximum for edentulous males on the right side and were minimum for dentulous females on the left side. The results were statistically significant for both antegonial and gonial angles (P ≤ 0.05%) [Table 4] and [Graph 1].{Table 1}

Table 4: Variation of values of antegonial angle, antegonial depth, gonial angle, and mandibular cortical index with in different age groups (One-way ANOVA)

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  Discussion Top


In this study, statistically significant relation was observed between the mean antegonial angle, depth, gonial angle, and MCI with respect to the age, gender, and dentition status. The value of antegonial angle decreased with an increase in age and edentulousness, while antegonial depth increased with age and edentulousness.[17] Females had higher values of antegonial angles as compared to males, while males had more antegonial depth as compared to females.[18] The results of this study were in accordance with the results of a study of Dutra et al. and Ghosh et al. Findings concerning gender differences may also be explained by the fact that, on average, men have greater masticatory force than women.[19] The present study shows a decrease in the gonial angle till age Group III (40–49 year) than increases from Group IV and V with edentulousness. The findings are probably because of the generally altered mandibular basal bone morphology associated with decreased masticatory muscle functioning as a result of tooth loss. These results confirmed a widening of the gonial angle in edentulous individuals. These results were consistent with the results of the study of Upadhyay et al., Hummonen et al., and Chole et al. They showed that gonial angle increases with edentulousness.

Categories of MCI (C1/55.2%, C2/32.7%, and C3/12.1%) were detected. These results were coinciding with the results of Hastar et al. (C1 = 53.1%) and contrasting with the results of Ledgerton et al. (C2 = 55.3%) and Gaur et al. (C2 = 52.3%). There was a statistically significant difference in the categories of MCI between men and women. Categories C1and C3 were more frequently seen in women, while Category C2 was more frequently seen in men. Dental status was significantly different according to the categories of MCI. Categories C1and C3 were more frequently present in dentulous patients (D) and minimum in edentulous individuals (E)[20],[21],[22],[23],[24],[25] Category C2 was more frequently observed in dentulous individuals and edentulous individuals. These results were coinciding with the results of Hastar et al. and Gulsahi et al., which demonstrated that the C2 category was more prevalent in dentate individuals, but the results were statistically insignificant. Cortical width was categorized based on Klemetti et al. criteria to predict if patients are at risk of osteoporosis. While comparing the mean values of antegonial angle on the right and left sides, the left side values were more than the right side values in each group. The mean values of Gonial angle were more on the right side than the left side in each age group. There was a sstatistically ignificant difference in the values of gonial angle and antegonial angle between the age groups (P ≤ 0.05). The results were coinciding with the results of Ghosh et al., Enlow et al., Dutra et al., and Upadhyay et al. who found that the values of antegonial angle were more on the left side than the right side and vice versa for gonial angle.[26]

Differences in the right as well as left side antegonial and gonial region suggest that resorption of the right antegonial region occurred more as compared to the left antegonial region and vice versa for gonial angle, hence proving the inherent nature of asymmetry of the human mandible. It strengthens findings that even in the absence of malformation or skull base asymmetry, the mandible may be physiologically asymmetric.[27] It can be said that the antegonial notch and gonial region is probably a good indicator of how the mandible growth occurs.

The mean values of antegonial angle decreased with respect to edentulism. The values were maximum for dentate individuals on the left side and minimum for edentulous individuals on the right side. Hence, we draw an inference that the values of antegonial angle in edentulous individuals on the right side were less, while the values were maximum for dentulous individuals on the left side. The results of this study were coinciding with results of Ghosh et al. and Dutra et al. The mean values of gonial angle increased with respect to edentulism.[28] The values were maximum for edentulous individuals on the right side and minimum for dentulous individuals on the left side. The inference is that the values of gonial angle in edentulous individuals were maximum on the right side, whereas the values were minimum for dentulous individuals on the left side. This may be attributed to the atrophic alterations of the basal part of the mandibular bone. The results were statistically significant for both antegonial and gonial angles. These results were coinciding with the results of study of Casey et al. and Emrich et al., who stated that there is an increase in the mean gonial angle in the edentulous group on the right side, but the results were statistically insignificant.[29] The mean values of antegonial angle decreased with respect to dentition. On comparing dentition status and gender, the values of antegonial angle were more in dentate females on the left side, while they were least in edentulous males on the right side.

The mean value of gonial angle increased with dentition status. On comparing dentition status and gender, the values of gonial angle were maximum for edentulous males on the right side and were minimum for dentulous females on the left side. The results were statistically significant for both antegonial and gonial angles (P ≤ 0.05%). The results of Dutra et al. were coinciding with the present study but were statistically nonsignificant, while the results of the study of Larheim et al., and Becker et al. were contrasting with this study.[30],[31],[32]


  Conclusion Top


The present study demonstrated that dentition status plays an equally important role in the remodeling process as age. The antegonial angle decreased with advancing age and thereby increased the antegonial depth. Females had deeper antegonial notches as compared to males. An inherent asymmetry in the antegonial regions between the right and left sides was one of the major conclusions of the present study. There seems to be a difference in gonial angle with different age groups, dentition status, and between gender as well. Thus, the gonial angle can serve as an adjuvant and additional forensic parameter, which guides for age group assessment and gender identification. MCI categorized according to Klemetti et al. criteria is definitely reliable and can be used as a diagnostic tool for screening patients with or without osteoporotic changes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

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



 

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