|Year : 2022 | Volume
| Issue : 3 | Page : 324-328
Prevalence and anatomic variations of lingual foramina and lingual canal in anterior mandible using cone beam computed tomography – A cross-sectional study
Sindhu Poovannan1, T Sarumathi2
1 Department of Oral Medicine and Radiology, Tagore Dental College and Hospital, The Tamil Nadu Dr. M.G.R. Medical University, Rathinamangalam, Chennai, Tamil Nadu, India
2 Department of Oral Medicine and Radiology, Sree Balaji Dental College and Hospital, BIHER, Pallikaranai, Chennai, Tamil Nadu, India
|Date of Submission||25-Jan-2022|
|Date of Decision||29-Aug-2022|
|Date of Acceptance||06-Sep-2022|
|Date of Web Publication||26-Sep-2022|
Senior Lecturer, Tagore Dental College and Hospital, Rathinamangalam, Chennai - 600 127, Tamil Nadu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Rich neurovascular supply in the anterior mandible necessitates a preoperative radiological assessment of the lingual foramina/canal where cone beam computed tomography (CBCT) could produce promising results. Aim: To assess the prevalence of lingual foramina and canal in mandible and variations in their anatomy in a hospital-based population in Chennai. Methodology: Sagittal sections of the anterior mandible from CBCT images of 140 patients were evaluated for number, location of the lingual foramen, length of the lingual canal, a distance of lingual foramen from the alveolar crest and inferior border of the mandible, and thickness of the lingual cortex. Results: A total of 166 lingual foramina-canals were identified in 140 individuals; 82.1% presented with one, 15.1% with two, and 2.1% with three lingual foramina canals. The majority of foramina (79.51%) were located above the genial tubercles. The mean lengths of the superior, middle, and inferior canals were 5.45 ± 1.34, 5.00 ± 1.73, and 3.92 ± 1.10 mm, respectively. The mean thickness of the lingual cortex was 2.35 ± 0.55 mm. The distance from the inferior lingual foramina to the alveolar crest was significantly greater in males (P = 0.001). Conclusion: Anatomical characteristics of lingual foramen-canal varied significantly across the total sample.
Keywords: CBCT, cross-sectional study, lingual canal, lingual cortex, lingual foramen
|How to cite this article:|
Poovannan S, Sarumathi T. Prevalence and anatomic variations of lingual foramina and lingual canal in anterior mandible using cone beam computed tomography – A cross-sectional study. J Indian Acad Oral Med Radiol 2022;34:324-8
|How to cite this URL:|
Poovannan S, Sarumathi T. Prevalence and anatomic variations of lingual foramina and lingual canal in anterior mandible using cone beam computed tomography – A cross-sectional study. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Dec 10];34:324-8. Available from: http://www.jiaomr.in/text.asp?2022/34/3/324/356964
| Introduction|| |
A foramen is an orifice that forms the entrance of bony canals. The median lingual foramen is located on the lingual aspect of anterior mandible at the anatomical midline, near the genial tubercles. The lingual canal is found in association with this foramen. The number of lingual foramina can range from one to three or even four.,
The lingual portion of anterior mandible has a very rich vascular supply. Trauma to the foramen/canal during dental procedures, such as implant placement, biopsy, enucleation, and minor surgery, could become life threatening to severe bleeding and acute oropharyngeal airway obstruction., Such conditions require emergency tracheostomy and prompt hospital management.
Therefore, given the risk factors, sincere efforts must be made for preoperative radiological treatment planning in the anterior mandible. The shift from 2D images to 3D images with the advent of cone beam computed tomography (CBCT) in dental practice has upgraded diagnostics. CBCT detects lingual foramen up to 100%, the reason being high resolutions at voxel 0.3 mm or even less on all three planes.,
The study aimed to assess the prevalence of lingual foramina and lingual canal in the mandible and variations in their anatomy among the hospital-based population of Chennai using CBCT images.
| Methods|| |
The study obtained approval from the Institutional Ethics Committee – Sree Balaji Dental College and Hospital (Certificate number: SBDCH/IEC/04/2019/18, approval date: 5th June 2019) and was in accordance with the 1964 Helsinki Declaration and its later amendments.
A cross-sectional study was performed for 3 months on CBCT images of patients from hospital-based population of Chennai. The sample estimated to be 140 at 95% confidence interval and was calculated using OpenEpi software, Version 3.0. 140 CBCT images belonging to both male and female patients aged between 19 and 76 years were obtained by convenience sampling. Required images were obtained from a private diagnostic scan center using My Ray Sky View 3D CBCT machine with a 9 × 6 field of view.
The exclusion criteria of the study were CBCT scans of patients aged less than 18 years, presence of a cyst, tumors, bony malformation or surgical procedures, especially in the anterior mandible, and poor quality of CBCT scan with scatter or insufficient accuracy of the region of interest.
CBCT data were reformatted using NNT iRYS viewer software. The anterior mandible was studied in sagittal sections with thickness slices and an interval of 0.227 mm.
The lingual foramina were first located using a magnification tool and the number of foramina and associated canals were identified (one or more than one) [Figure 1]a, [Figure 1]b, [Figure 1]c. Also the location of lingual foramina was recorded as either above or below the genial tubercles.
|Figure 1: Sagittal section of anterior mandible representing number of lingual foramina (a) single lingual foramen-canal (b) two lingual foramina-canals (c) three lingual foramina-canals|
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Then, the following parameters were analyzed and measured in millimeters using the software tools:
- Length of the lingual canal [Figure 2]a.
- Distance from the alveolar crest till the superior, middle, and inferior lingual foramina.
- Distance from the inferior border of the mandible till the superior, middle, and inferior lingual foramina.
- Thickness of lingual cortical plate.
|Figure 2: Sagittal section of anterior mandible representing measurements in millimeters of (a) length of lingual canals (b) distance from the superior lingual foramen till alveolar crest (c) distance between the superior lingual foramen till mandibular inferior border (d) distance from inferior lingual foramen till mandibular inferior border and alveolar crest (e) lingual cortex thickness|
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For distance measurements, two tangent lines were drawn, one at the level of the mandibular inferior border and the other along the alveolar crest. The vertical distance between the tangent line is drawn at the alveolar crest/mandibular inferior border till the superior lingual foramina were measured [Figure 2]b and [Figure 2]c.
The measurements were repeated for all (one, two, or three) the canals present. [Figure 2]d.
The thickness of the lingual cortex was measured just above the superior lingual foramen because perforation of the lingual cortex in this region will likely damage the vasculature of the canal [Figure 2]e.
The data were analyzed using IBM SPSS software, version 21. Normality was checked using the Shapiro–Wilk test, which revealed that the data followed a normal distribution. An independent t-test was used to assess measurement parameters – continuous variables. A Chi-square test was applied for categorical variables. The P value was set at 0.05, which is attributable to statistical significance*.
| Results|| |
Among the 140 CBCT images analyzed, 83 (59.3%) were male and 57 (40.7%) were female. After a thorough examination, 166 lingual foramina-canals were identified from the total sample.
The mean age of the patients was 41.66 ± 16.57, ranging from 19 to 76 years. The age was similarly distributed among the male and female gender (P = 0.477).
Among the 140 individuals, 115 (82.1%) presented with one lingual foramen and canal. The remaining showed more than one foramen, in which 21 (15.1%) consisted of two lingual foramina-canals, and three (2.1%) patients had three lingual foramina-canals. The foramen could not be identified and located in one (0.7%) individual.
In relation to the genial tubercles, the majority of the lingual foramina (132 [79.51%]) were positioned superior to the genial tubercle, and 34 (20.49%) were situated inferiorly.
Anatomical features of the lingual foramen-canal varied with significance among the entire sample. The mean lengths of the superior, middle, and inferior canals are 5.45 ± 1.34, 5.00 ± 1.73, and 3.92 ± 1.10 mm, respectively.
The mean distance from the alveolar crest to the superior, middle, and inferior lingual foramina was 13.35 ± 3.44, 20.46 ± 0.55, and 24.54 ± 3.18 mm, respectively. The mean distance from the mandibular inferior border to the superior, middle, and inferior lingual foramina was 14.35 ± 2.59, 10.80 ± 4.18, and 4.63 ± 1.78 mm, respectively.
The thickness of the lingual cortex ranged from a minimum of 1.2 mm to a maximum of 3.7 mm, with a mean value of 2.35 ± 0.55 mm [Table 1].
|Table 1: Independent t-test statistics of length of the lingual canal, distance from alveolar crest, distance from inferior border, and thickness of lingual cortex|
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The distance measured from the alveolar crest to the inferior lingual foramen was greater in males than in females with statistical significance (P = 0.001) [Table 1]. Neither the number of foramina [Table 2] nor the location of foramen [Table 3] displayed statistically significant gender-related differences. No statistically significant correlation was found between age and lingual foramina parameters.
|Table 2: Chi-square test statistics for the number of lingual foramen according to gender|
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|Table 3: Chi-square test statistics for lingual foramen location relative to genial tubercles according to gender|
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| Discussion|| |
In our sample, 99.3% showed at least one lingual foramen, which could not be located in only one patient. Our findings are consistent and agree with the following authors: Gahleitner et al. detected 96.9% of the median lingual foramen, Scaravilli et al. detected 90.4%, and Kilic et al. recorded 96.5% using a computed tomogram. Von Arx et al. found 96.2% and Sekerci et al. who studied a larger sample size of 500 mandibles recorded 95.2% using CBCT tomogram. McDonnell et al. studied 314 dry mandibles and found the median lingual foramen in 99% of the samples.
The finding of the present study with regard to the presence of lingual foramen disagrees with Sheikhi et al., Tepper et al., Babiuc et al., and Rosano et al., where the identification of at least one mandibular lingual foramen was 100%. The differences could be because of the smaller sample size or ethnicity variation among the studies.
In the current study, single lingual foramen was the most frequent occurrence (82.1%), followed by two (15.1%) and three foramina (2.1%). This result corroborates with findings of Tepper et al., Liang et al., Babiuc et al., Kilic et al., and Sekerci et al. Even up to five lingual foramina have been identified by Gahleitner et al. The findings of this study with regard to number of foramina, disagree with Rosano et al., Von Arx et al., Sheikhi et al., and Choi et al. who identified two lingual foramina as the most frequent occurrence.
In the present study, majority of the foramen were positioned superior to the genial tubercles (79.51%). When more than one foramen was detected, one was present superior and the remaining inferior to the genial tubercles. The findings support the studies conducted by Babiuc et al. and Sheiki et al.
The mean values of the length of superior, middle, and inferior canals in the present study are slightly lower than the findings of Sheikhi et al.
The mean values of distance measured from the superior, middle, and inferior foramen to the alveolar crest and mandibular inferior border of the present study are in agreement with the observation of Sheikhi et al., Babiuc et al., Choi et al., and Cova et al.
Mean value for thickness of lingual cortex in the present study strongly corroborates with the finding of Dennis Flanagan.
The distance from inferior lingual foramen till the alveolar crest was significantly higher in males than in females with a P value of 0.001. Whereas in study conducted by Georges Aoun et al. in Lebanon population, distance measured between superior lingual foramina and the crest of mandibular alveolus was greater in males (17.12 ± 2.88 mm) than in females (15.45 ± 2.54 mm) with statistical significance (P = 0.006).
Implications of present study
- Recognize and appreciate the lingual foramen as an anatomic landmark to assess the location of arterial supply.
- Realizing the significance of preoperative treatment planning in anterior mandible.
- Judicious use of dental CBCT for its superior quality and precision.
- Perform procedures in anterior mandible with safe protocol to avoid bizarre complications.
| Limitations and Future Study Prospects|| |
Although results of the study are highly reliable, it cannot be extrapolated to the global population because of the ethnic variations. Future studies are required to analyze the prevalence and anatomic variations of lingual foramen among various ethnic groups of world population.
| Conclusion|| |
Within the limits of this study, anatomical characteristics of the lingual foramen-canal with regard to number, location, length of canal, and distance from foramen to alveolar crest and inferior border of mandible varied across the total sample.
Precise preoperative planning is essential before dental procedures in the anterior mandible, which can be effectively achieved using CBCT.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]