Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2015  |  Volume : 26  |  Issue : 6  |  Page : 571--575

Localization of mandibular foramen relative to landmarks in East Indian mandibles


Kumari Sandhya1, Bhoopendra Singh2, Namita Lugun1, Renu Prasad1,  
1 Department of Anatomy, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India
2 Department of Forensic Medicine and Toxicology, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India

Correspondence Address:
Dr. Bhoopendra Singh
Department of Forensic Medicine and Toxicology, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand
India

Abstract

Context: The position of mandibular foramen (MF) is an important anatomical landmark for effective anesthesia in dentistry for many procedures, including dental extraction from the lower jaw and putting mandibular implants. Several causes have been examined in this context, and the uncertainty in the location of the MF has been examined to be a major factor for the high failure rate of anesthesia and complications of the orthodontic procedure. Aims: The purpose of this study was to examine and analyze the position of the MF relative to six bony landmarks on the ramus in the population of Jharkhand. Subjects and Methods: The different parameters were measured in 30 dry adult«SQ»s mandibles that were obtained from the Department of Anatomy. The data were tabulated and statistically analyzed. Statistical Analysis Used: Paired t-test. Results: The mean distance between the MF and the respective landmarks was noted as 16.00 ± 3.50 mm for the anterior border, 10.21 ± 2.34 mm for the posterior border, 20.48 ± 3.89 mm for the superior border, 24.15 ± 4.97 mm for the inferior border, 33.46 ± 6.08 mm for the condyle, and 12.31 ± 4.88 mm for the internal oblique ridge for the right side. On the left side, these distances were 16.27 ± 3.9 for the anterior border, 10.28 ± 5.24 for the posterior border, 20.15 ± 3.8 for superior border, 24.86 ± 4.04 for inferior border 32.48 ± 4.73 for condyle, and 10.93 ± 4.06 for the inferior oblique ridge. Statistically, there was no significant difference in the distance to either side from selected 5 landmarks, the only exception being the condyle. Conclusions: Condyle and internal oblique ridge have been shown to be two new landmarks that may be used to find MF. Bilateral symmetry has been shown for all landmarks except for condyle.



How to cite this article:
Sandhya K, Singh B, Lugun N, Prasad R. Localization of mandibular foramen relative to landmarks in East Indian mandibles.Indian J Dent Res 2015;26:571-575


How to cite this URL:
Sandhya K, Singh B, Lugun N, Prasad R. Localization of mandibular foramen relative to landmarks in East Indian mandibles. Indian J Dent Res [serial online] 2015 [cited 2019 Jun 20 ];26:571-575
Available from: http://www.ijdr.in/text.asp?2015/26/6/571/176917


Full Text

Mandibular foramen (MF) is an opening on the internal surface of the ramus that leads into the mandibular canal. This canal curves downward and forward in the body to the mental foramen. [1] The inferior alveolar vessels and nerves enter through the MF, traverse the canal, providing branches to all teeth and exit through the mental foramen as mental nerve and vessel. [1] MF is an important anatomical landmark not only for oral maxillofacial surgery like sagittal split osteotomies done to reposition the mandible in prognathism and retrognathia [2] but it is also significant in connection with effective anesthesia in dentistry while doing the inferior alveolar nerve block (IANB). [3]

It has been observed and reported by different researchers that the main complications encountered during sagittal split osteotomies are hemorrhage, injury to the neurovascular bundle, undesired fractures, and bone necrosis when the proper location of MF is not clear. Hence, a thorough knowledge of the MF and ramus is essential for orthodontic surgeries too. [4]

A study conducted by Meechan [5] in 1999 and observed that the failures of anesthesia may stem from both the operator and patient dependent factors. Such factors range from a choice of technique to anatomical, pathological, and psychological reasons. There are many articles published in various scientific journals, describing the importance of the anatomical structures in relation to the MF relevant to successful mandibular anesthesia. A high failure rate still persists for this technique that has been reported by many workers like Potocnik and Bajrovic [6] have estimated the failure rate of IANBs to be approximately 30-45%. [6] While according to Shah et al. [7] the failure rate of IANBs was found to be approximately 20-25%. [7]

Thangavelu et al. [8] have described the significance of localization of MF in an IANB.

Studies have shown the racial differences in the anatomy of the mandible. The literature contains conclusive evidence that significant metric, morphological, and biological differences are present among the three major racial phenotypes, caucasoid, mongoloid, and negroid. [9],[10]

There are significant differences reported on the location of MF among different racial groups. [11],[12],[13]

The aim of the study is to determine the precise location of the MF in relation to the borders of the mandibular ramus and to locate the quadrant of the ramus in which the mandible foramen is located in the East zone of the Indian population (Jharkhand).

Objective

The purpose of this study was to evaluate four broadly studied bony landmarks and investigate two newly selected bony landmarks relative to MF to assist the process of IANB. It was also sought to determine whether bilateral symmetry existed for each of these landmarks with respect to the position of the MF.

 Subjects and Methods



The study was conducted on a sample set of 30 dry mandibles of both sexes, available in the Department of Anatomy. This included 26 dentulous and 4 edentulous bones. The various landmarks used for measurements are illustrated in [Figure 1]. The distance was measured to the nearest of 0.1 mm using Vernier Caliper. To define the distance from MF each landmark, point to point measurements were taken between the midpoint (center) of the foramen and the closest point on the respective landmark.{Figure 1}

H 0 : There is no difference between the distance from the chosen landmark to the MF on the right side and the left side.

H A : The distances from the chosen landmark to the MF on the right side and the left side are not equal.

Data were analyzed using SPSS version 10 for Windows (SPSS Inc., Chicago, IL, USA). Paired t-test was used to compare the left and right sides with the t-value and P < 0.05 considered significant. Quantitative data are given as mean ± standard deviation (SD) and standard errors were calculated for the six data sets. The paired t-test was applied for testing the null hypotheses for the data sets.

 RESULTS



The minimum, maximum, and mean distance of the MF from the closest point on the anterior border is detailed in [Table 1]. This includes data from both the left and right side of the mandible. [Table 1] also includes the SD and standard error for the dataset, as well as the t-value and P value for statistical analysis. It shows that the mean distance between the MF and the anterior border is 16.00 with SD 3.50, standard error 0.64 mm on the right side and 16.27 mm with SD 3.9 and standard error 0.73 mm on the left side. The analysis led to the acceptance of the null hypothesis.{Table 1}

There may be bilateral symmetry for the distance between the anterior border and MF as no evidence was found against H 0 at the 1% level of significance.

It shows that the mean distance between the MF and the posterior border is 10.21 mm with SD 2.34 mm and standard error 0.43 mm on the right side. On the left side, the mean distance was 10.28 mm with SD 5.24 mm and standard error 0.98 mm. The analysis led to the acceptance of the null hypothesis [Table 2].{Table 2}

The minimum, maximum, and mean distance of the MF from the closest point of the superior border is detailed in [Table 3]. This includes data from both the left and right side of the mandible [Table 3]. Also includes the SD and standard error for the dataset, as well as the t-value and P value for statistical analysis. It shows that the mean distance between the MF and the superior border is 20.48 mm with SD 3.89 mm, standard error 0.71 mm on the right side and 20.15 mm with SD 3.8 mm and standard error 0.71 mm on the left side. The analysis led to the rejection of the null hypothesis.{Table 3}

There may be bilateral symmetry for the distance between superior border and MF as no evidence was found against H 0 at the 1% level of significance.

The minimum, maximum, and mean distance of the MF from the closest point of the inferior border is detailed in [Table 4]. This includes data from both the left and right side of the mandible [Table 4]. Also includes the SD and standard error for the dataset, as well as the t-value and P value for statistical analysis. It shows that the mean distance between the MF and the inferior border is 24.15 mm with SD 4.97 mm standard error 0.91 on the right side and 24.86 mm with SD 4.04 mm standard error 0.75 mm on the left side. Analysis led to nonrejection of the null hypothesis.{Table 4}

There may be bilateral symmetry for the distance between inferior border and MF as no evidence was found against H 0 at the 1% level of significance.

The minimum, maximum, and mean distance of the MF from the closest point on the condyle is detailed in [Table 5]. This includes data from both the left and right side of the mandible. [Table 5] also includes the SD and standard error for the dataset, as well as the t-value and P value for statistical analysis. It shows that the mean distance between the MF and the condyle is 33.46 mm with SD 6.08 mm and standard error 1.1 mm on the right side and 32.48 mm with SD 4.73 mm and standard error 0.86 mm on the left side. Analysis of data reveals rejection of the null hypothesis at 1% level of significance.{Table 5}

There is no bilateral symmetry for the distance between the condyle and MF.

The minimum, maximum, and mean distance of the MF from the closest point of the internal oblique ridge is detailed in [Table 6]. This includes data from both the left and right side of the mandible. [Table 6] also includes the SD and standard error for the dataset, as well as the t-value and P value for statistical analysis. It shows that the mean distance between the MF and the internal oblique ridge is 12.31 mm with SD 4.88 mm and standard error 0.9 mm on the right side, whereas on the left side the mean distance was 32.48 mm with SD 4.73 mm and standard error 0.86 mm. The analysis led to rejection of the Null hypothesis.{Table 6}

There may be bilateral symmetry for the distance between internal oblique ridges to MF as no evidence was found against H 0 at 1% level of significance.

 DISCUSSION



The present study is conducted on the mandibles of the population of Jharkhand (East Zone) in India. The findings of this study may be utilized by the dental surgeons in assessing the position of the MF in the local population while using the inferior alveolar block for local anesthesia. In this study, it was found that the MF was situated at a mean distance of 1.29 mm (right) and 1.78 mm (left) posterior from the midpoint of the anteroposterior (AP) dimension of ramus that is consistent with the findings of studies carried out by Mbajiorgu, [11] Hetson et al. [14] and Hayward et al. [15] Mbajiorgu [11] who worked on the Zimbabwean's sample, showed that the position of the MF was highly individualistic, but on average lies at about 2.56 mm (right) and 2.00 mm (left) behind the midpoint of ramus width.

Hetson et al. [14] stated that the MF was located immediately posterior to the center of the ramus. Whereas Hayward et al. [15] states that it is located in 3 rd quadrant anteroposteriorly. In this study, the mean distance of MF from the anterior border of ramus was 16 mm on the right side and 16.27 mm on the left side and that from posterior border was 10.21 mm and 10.28 mm on the right side and left side respectively, which was very much similar with the findings of Hoque et al. [16] in Bangladesh and Varma et al. [17] in South India. Hoque et al. [16] conducted a study on Bangladeshi population and reported that the mean distance of MF from anterior border of ramus was 16.34 mm on the right side and 16.27 mm on the left side. Varma et al. [17] found it as 16.52 mm on the right side and 16.94 mm on the left side and a mean distance of MF from posterior border 13.35 mm on the right side and 13.46 mm on the left side in the South Indian Mandibles.

Hayward [15] in their study stated that the mean size of the anterior dimension was greater than the mean size of the posterior dimension of the ramus in all instances; the MF was found to be located in the third quadrant anteroposteriorly; there was no right- or left-side dominance in the ramus size and position of the MF.

Thangavelu et al. [8] found in their study that the MF was positioned at a mean distance of 19 mm (with SD 2.34 mm) from the anterior border of the ramus. The variability of distance from AB to MF was also not significant enough to produce failure of anesthesia. If we compare our work with some other ethnic groups, then we see that the distance of the MF to the angle of the anterior ramus which were 16 mm and 16.27 mm on the right and the left side, respectively in our study, these were 16.9 mm on the right and 16.78 mm on the left side in Turkish population as reported by Oguz and Bozkir. [12] According to Lee [13] whose study was on Korean samples, the MF was located posteriorly to the midpoint of the AP width of the ramus. It was located at 57.3% of the AP width of the anterior border. At the same scale, our study showed MF to be located at 61.04% of the AP width of the anterior border so here also our value differs that found in Korean samples. In the vertical dimension, the MF was found at a mean distance of 20.48 mm (right) and 20.15 mm (left) from the mandibular notch in our study. In south India by Varma et al. [17] this distance was reported as 23.39 (right) and 24.41 (left) in dentulous and 21.65 (right) 20.92 (left) in edentulous sample. When it was taken in reference to mid-point of MF, then it was located 1.79 mm (right) and 1.56 mm (left) superior to the midpoint. This differed from studies carried out by Nicholson [18] according to them the MF was predominantly located at the center of the mandibular ramus. Our results were in accordance with the results found by Williams et al. [19] study, and Oguz and Bozkir. [12] According to Williams et al. [19] study the MF was located above the center of the ramus on the medial surface. At the same time, Oguz and Bozkir, [12] studied Turkish sample and reported the distance of the lowest point of the mandibular notch to the foramen was 22.37 mm on the right and 22.17 mm on the left. The distance from the MF to the inferior border of the ramus in the mid position of the ramus was 30.97 mm on the right and 29.75 mm on the left side. Again, while comparing with some other ethnic groups, we notice that Mbajiorgu [11] reported MF to be approximately 3 mm superior to the midpoint of rameal height on both sides in the Zimbabwean's sample. Work done by Oguz and Bozkir [12] on Turkish sample showed that the MF was located superiorly to the midpoint on the vertical height of the ramus, on the 48.5% of the vertical distance from the coronoid notch.

The findings of a study conducted by Narayana et al. [20] study indicated the bilateral symmetry of the MF by assessing human dry mandibles; in our study also, there was no significant difference between the right and left a side. He further stated the MF was located above the center of the ramus on the medial surface. In our study, a distance of MF from condyle was 33.86 on the right side and 32.48 mm on the left side which is quite different with the results found by Thangavelu et al. [8] They reported that this distance as 38.14 mm on the right side and 37.60 mm on the left side. However, our result showed significant bilateral asymmetry, and this was consistent with the work done by Thangavelu et al. [8]

Clinical implication

The dental surgeons can utilize this information during the local anesthesia involving the inferior alveolar nerve (IAN) for different procedures such as dental extraction, placement of mandibular implants, and other therapeutic procedures involving mandibles in the local population of Jharkhand. Clinicians can also use internal oblique ridge and temporomandibular joints (condyles), as a reference point for planning different techniques of IAN block (IANB).

 CONCLUSION



Our study showed that the MF was located in the posterosuperior quadrant of the ramus. On the right side, it was located at a mean distance of 1.29 mm posterior to the midpoint of the AP dimension and 1.79 mm superior to the midpoint of vertical dimension. On the left side, it was 1.78 mm posterior from the midpoint of the AP dimension and 1.56 mm superior to the midpoint in the vertical dimension. The dental surgeon can utilize this information during the anesthetic procedures involving the IAN. Clinicians can also use internal oblique ridge and temporomandibular joints (condyle), as a reference point for planning different techniques of IANB.

Acknowledgment

We would like to acknowledge the contribution made by Dr. V. Dhar for helping us in selecting an appropriate statistical tools and methods to analyze the data. Furthermore, we would also like to acknowledge Mrs. Toshe for her continued encouragement during the work and assistance in computer application and Mr. Rataneswar Malik (Attendent) for his assistance in handling the bones.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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