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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 31  |  Issue : 2  |  Page : 123-127

An anatomic and radiographic study of medial sigmoid depression in human mandible


1 Department of Oral Pathology/Oral Medicine and Radiology, Dr.Z.A. Dental College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, Career Postgraguate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India

Date of Submission29-Dec-2018
Date of Acceptance02-Jan-2019
Date of Web Publication24-Jun-2019

Correspondence Address:
Dr. Md Asdullah
Department of Oral Pathology/Oral Medicine and Radiology, Dr.Z.A. Dental College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh - 202 002
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_218_18

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   Abstract 


Introduction: Medialsigmoid depression (MSD) is well-defined radiolucency in the inferior aspect of sigmoid notch seen on the few panoramic radiographs. Anatomically, MSD corresponds to a depression on medial side of upper ramus just below the sigmoid notch. The significance of this normal anatomical landmark lies in its propensity to be misinterpreted on the panoramic radiograph as a defect or a pathological entity especially a cyst. Aim and Objective: To study the prevalence of the medial sigmoid depression of mandibular ramus in dry humanmandible anatomically and radio- graphically and on panoramic radiograph of patients. Materials and Methods: The study consisted of Panoramic radiographs of the50 dry human mandibles and 50 Panoramic radiographs of adult out-patient (selected randomly) visiting the Department of Oral Medicine and Radiology was taken. The entire selected mandibles included in the study were evaluated for the medial sigmoid depression. Panoramic radiographs of the selected mandibles were made using X-Mind Pano Ceph 1800 VA (SATELEC) panoramic machine and were interpreted for the various parameterspertaining to medial sigmoid depression. Results: The medial sigmoid depression (MSD) was present among 70% of the patients and in 82% of mandibles. The findings ofMSD was similar by anatomically and radio logically among the mandibles. The presence of MSD was 27% insignificantly (P > 0.05) lower in patients compared with mandibles (RR = 0.73, 95%CI = 0.49-1.09, P = 0.16). The presence of MSD was higher among the male patients (76%) rather than in females (64%). Conclusion: The recognition of MSD was quite competent in anatomic specimen, panoramic radiograph of the specimen and patients. Its appearance may be considered as a normalvariants on the panoramic radiographs.

Keywords: Human mandible, medial sigmoid depression, panoramic radiograph


How to cite this article:
Asdullah M, Aggarwal A, Khawja KJ, Khan MH, Gupta J, Ratnakar K. An anatomic and radiographic study of medial sigmoid depression in human mandible. J Indian Acad Oral Med Radiol 2019;31:123-7

How to cite this URL:
Asdullah M, Aggarwal A, Khawja KJ, Khan MH, Gupta J, Ratnakar K. An anatomic and radiographic study of medial sigmoid depression in human mandible. J Indian Acad Oral Med Radiol [serial online] 2019 [cited 2019 Jul 21];31:123-7. Available from: http://www.jiaomr.in/text.asp?2019/31/2/123/261082




   Introduction Top


Medial sigmoid depression (MSD) is well-defined radiolucency in the inferior aspect of sigmoid notch seen on the few panoramic radiographs.[1] Anatomically, MSD corresponds to a depression on medial side of upper ramus just below the sigmoid notch.[2] The significance of this normal anatomical landmark lies in its propensity to be misinterpreted on the panoramic radiograph as a defect or a pathological entity especially a cyst. Medial depression of the mandibular ramus (MDMR), or medial sigmoid depression has been described as consequence of a slender mandibular ramus in the area of the sigmoid notch.[3],[4] The decreased absorption of X-rays produces a radiolucent artifact in this area on panoramic radiographs. The depression may be unilateral or bilateral and may be misinterpreted as a pathological condition.[3],[4] Medial sigmoid depression may also increase the potential for complications in orthognathic surgery for dentoskeletal deformities due to an increased difficulty in splitting the ramus. Bleeding, paresthesia, and relapse may occur.[1],[2]


   Materials and Methods Top


The study consisted of 50 dry human mandibles obtained from the Department of Anatomy, Career Medical College and Hospital Lucknow. There are about 50 Panoramic radiographs of the same dry human mandibles, and 50 Panoramic radiographs of adult out-patient (Selected randomly) visiting the Department of Oral Medicine and Radiology was taken.

The entire selected mandibles included in the study were evaluated for the Medial sigmoid depression. Panoramic radiographs of the selected mandibles were made using X-Mind Pano Ceph 1800 VA (SATELEC) panoramic machine and were interpreted for the various parameter spertaining to medial sigmoid depression.

Dry mandible and radiographs of dry mandible showing different shapes of medial sigmoid depression [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10].
Figure 1: Left-teardrop, right-Semilunar

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Figure 2: Left-circular, right-triangular

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Figure 3: B/L –Absent of MSD

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Figure 4: OPG of same mandible showing B/L absent

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Figure 5: Right side-semilunar shape

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Figure 6: Left side of same mandible –Absent MSD

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Figure 7: OPG of same mandible right- semilunar, left-absent

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Figure 8: Bilateral absence of MSD

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Figure 9: Unilateral absence of MSD, right-tear drop, left-absent

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Figure 10: Bilateral presence of MSD, right- semilunar, left-triangular

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The written consent was obtained from selected patient. The panoramic radiographs of these 50 selected patients were made using the selected X-Mind Pano Ceph 1800 VA (SATELEC) Panoramic machine and were interpreted for the various parameters pertaining to Medial Sigmoid Depression.

The data collected were tabulated. Results were subjected to statistical analysis and the conclusions were drawn.


   Results Top


The findings of Medial sigmoid depression (MSD) was similar by anatomically andradio logicallyamong the mandibles.

The average age of the patients was 32.16 (±10.17). About half of the patients were between 20-30 (48%) years followed by 31-40 years (24%), 41-50 years (12%) and >50 and <20 years (8%) [Bar diagram 1].



[Table 1], and [Bar diagram 2]- presents the presence/absence of medial sigmoid depression in patients and mandibles. The medial sigmoid depression (MSD) was present among 70% of the patients and in 82% of mandibles.The presence of MSD was 27% insignificantly (P > 0.05) lower in patients compared with mandibles (RR = 0.73, 95%CI = 0.49-1.09, P = 0.16).
Table 1: Presence/Absence of medial sigmoid depression in patients and mandibles

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[Table 2], and [Bar diagram 3]- depicts the side of medial sigmoid depression in patients and mandibles. The percentage of unilateral side of MSD was higher among the patients (22.9%) compared to mandibles (14.6%). However, bilateral was lower among the patients than mandibles. The unilateral side was 1.31 times insignificantly higher among the patients than mandibles (RR = 1.31, 95%CI = 0.76-2.24, P = 0.35).
Table 2: Side of medial sigmoid depression in patients and mandibles

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[Table 3], and [Bar diagram 4]- describes the distribution of patients and mandibles according to shape. The right side shape in Triangular was significantly lower among the patients (14%) than mandibles (34%) and this was 49% lower in patients compared to mandibles (RR = 0.51, 95%CI = 0.26-0.99), P = 0.01). The similar observation found for left side shape in Triangular between patients and mandibles. However, the right side shape in semilunar was significantly higher in patients (42%) than mandibles (22%) and this was 1.53 times higher in patients compared to controls (RR = 1.53, 95%CI = 1.06-2.23, P = 0.03). There was no significant (P > 0.05) difference in the right and left side of Teardrop and Circular shape between patients and mandibles.
Table 3: Distribution of patients and mandibles according to shape of MSD

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[Table 4], and Bar 3-The presence of MSD was higher among the males patients (76%) than females (64%) and this almost 2 times higher in males compared to females (OR = 1.78, 95%CI = 0.52-6.08, P = 0.35) [Table 4] and [Bar 3].
Table 4: Medial sigmoid depression according to gender among the patients

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   Discussion Top


In the present study, the prevalence of MSD on dry mandibles and radiograph of same dry mandible was found to be 82% among 50 dry mandibles [Table 2], and [Bar diagram 2]. The result were consistent with those of Divya A who in 2006 found the prevalence to be 74% among 100 mandibles, Langlais RP et al.in 1983found the prevalence to be 56% among 88 mandibles and againLanglais RP et al.in 1995 found prevalence to be 66%.[1],[2],[3]

However, the result differ from those of Clark MJ and Mc Anear who in 1983 found the prevalence to be 5% among 100 mandibles and Carvalho MM et al. in 2001 found the prevalence to be 33.9% among 251mandibles.[4],[5]

The discrepancy in results may be related to ethnic differences, discrepancy in the method used for interpretation ofMSD and variations in sample size.

Another important aspect contributed to discrepancy in the result is the method used for interpretation of MSD. All the investigator identified the landmark based on their visual interpretation. So, the result might be related to subjectivity of radiographic interpretation.

The occurrence of MSD can be unilateral or bilateral. In the present study, of the 41 mandibles with MSD, 6 (14.6%) mandibles had unilateral while 35 (84.5%) mandibles had bilateral presence of MSD [Table 3].

The results were consistent with those of Langlais RP et al. in 1983 who found the prevalence of unilateral MSD to be 25%, while differ in case of prevalence of bilateral MSD (31%) and withCarvalho MM et al. (in 2001, unilateral MSD 20%).

The discrepancy in the results may be related to asymmetric growth pattern.[6]

Carvalho MM et al. in 2001 defined the shapes of MSD as Triangle, Semilunar, Circular and teardrop on panoramic radiographs of patients.[4]

In our study, among the shapes the prevalence of Triangular were maximum followed by Semilunar, Circular and teardrop [Table 4], and [Bar diagram 4]. This finding is consistent with Divya A (2006), there is no other reports on prevalence of each shape of MSD on dry human mandibles to date.

In our study the prevalence of Medial Sigmoid Depressionon panoramic radiograph were found to be prevalence of 70% [Table 2], and [Bar diagram 2]. Further prevalence in 25 male patients was 76% and in 25 female patients was 64%.

This result was consistent with the result of Divya A who in 2006 found the prevalence of MSD was 64% among 100 panoramic radiograph of patients. This findings differ from result of Langlais et al. in 1983 who found the prevalence to be 10% among 1986 panoramic radiograph of patients and Carvalho MM et al. in 2001 found the prevalence to be 20.3% among 1358 panoramic radiograph of patients.[3],[4]

The discrepancy in results may be explained by ethnic differences, differences in panoramic machine useddiscrepancy in the method used for interpretation ofMSD and variations in sample size. The prevalence of MSD is found to be high in patients with dentofacial deformity in spite of positioning error being a common task in these patients.[7],[8]

The prevalence of semilunar shape was found to be high followed by triangular, teardrop and circular [Table 4], and [Bar diagram 4]. The result were consistent with Divya A (2006), however differ from Carvalho (2001) who found the prevalence of triangular shape to be more (39.7%).

This discrepancy may be related to asymmetric growth and positioning error. There the no other reports on the prevalence of each shape of MSD done with respect to sidethan Divya A (2006). The prevalence in 25 male patients was 76% and in 25 female patients was 64%[Table 4], [bar-3], although there was difference in the frequency of panoramic radiograph of male and female patients showing the MSD, that is statistically not significant (P = 0.35). This result was consistent with the result of Divya A who in 2006 found the prevalence of MSD 64% among 100 panoramic radiographs of patients ((54.7% in male and 45.3% in female) and Carvalho MM et al. in 2001 (22% in female and 18.3% in male). The findings differed from the result of Langlais et al. in 1983 who found the prevalence to be 10% among 1986 panoramic radiograph of patients and Carvalho MM et al. in 2001 who found the prevalence to be 20.3% among 1358 panoramic radiograph of patients.[3],[4] The discrepancy in results may be explained by ethnic differences, differences in panoramic machine used, differences in the method used for interpretation of MSD and variations in sample size.


   Conclusion Top


It can be concluded that the recognition of MSD was quite competent in anatomic specimen, panoramic radiograph of the specimen and patients. Its appearance may be considered as a normalvariants on the panoramic radiographs. Here, an attempt has been made to assess the nature of MSD with respect to gender, and shape. Thus, our study could be considered an opening for further studies with respect to different parameters of MSD.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Divya A. An Anatomical and Radiographic study of Medial Sigmoid Depression in Human Mandibular Ramus. Available from: http//hdl.handle.net/123456789/2659/D Space at RGUHS University 2005.  Back to cited text no. 1
    
2.
Langlais RP, Langland OE, Nortje CJ. Circumscribedradiolucency. In: Diagnostic Imaging of the Jaws. Baltimore: William and William; 1995. p. 241-61.  Back to cited text no. 2
    
3.
Langlais RP, Glass BJ, Bricker SL, Miles DA. Medial Sigmoid Depression: A panoramic pseudo foramen in the upper ramus. Oral Surg Oral Med Oral Path 1983;55:635-8.  Back to cited text no. 3
    
4.
Carvalho MM, Damante JH, Tallent RH, Ribeiro-RF. An anatomical and radiographic study of medial depression of the human mandibular ramus. Dentomaxillofac Radiol 2001;30:209-13.  Back to cited text no. 4
    
5.
Lynch DP, Newland JR, Mc Clendeon. JL. Myospherulosis of the hard andsofttissues. J Oral Maxillofac Surg 1984;4:349-55.  Back to cited text no. 5
    
6.
Kerr DA, Ash MM, Millard HD. Oral Diagnosis. 6th ed. London: CV MosbyCompany; 1983.  Back to cited text no. 6
    
7.
Clark MJ, Mc Anear JT. Pseudocystin the coronoid of the mandible. Oral Surg Oral Med Oral Pathol 1983;57:231.  Back to cited text no. 7
    
8.
Dalil Z, Motilavipous ST. Frequency of medial sigmoid depression in panoramic view oforthodontic. MedFaculty J Guilan Univ Med Sci 2003,12:721-3.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
 
 
    Tables

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



 

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