Prevalence of lingual foramina in the anterior mandible: A cone-beam computed tomography study

Julia Bellinazzi de Andrade Santos; Fabiano Capato de Brito; Eduardo Cláudio Lopes de Chaves e Mello Dias

doi:10.4103/jomr.jomr_4_20

ORIGINAL ARTICLE

Year : 2020 | Volume : 8 | Issue : 1 | Page : 10-15

Prevalence of lingual foramina in the anterior mandible: A cone-beam computed tomography study

Julia Bellinazzi de Andrade Santos, Fabiano Capato de Brito, Eduardo Cláudio Lopes de Chaves e Mello Dias
Department of Postgraduate, São Leopoldo Mandic, Campinas, SP, Brazil

Date of Submission	04-Mar-2020
Date of Decision	31-Mar-2020
Date of Acceptance	09-Apr-2020
Date of Web Publication	2-Jul-2020

Correspondence Address:
Julia Bellinazzi de Andrade Santos
61 Nestor Bras Pereira St, São Gabriel Da Palha, ES
Brazil

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jomr.jomr_4_20

Abstract

Context: Serious hemorrhagic complications can result from arterial trauma associated with perforation of the lingual cortical plate or injury to the terminal branches of the sublingual and submental arteries that pierce the lingual cortex of the mandible in the anterior region. Aim: The aim of this study is to determine the prevalence of lingual foramina (LF) in the anterior mandible by cone-beam computed tomography (CBCT) and to determine the presence and number of foramina, lingual foramina canal length (LFC), distance from the base of the mandible to the entrance of the LFC, distance from the base of the mandible to the end of the LFC, distance from the end of the LFC to the buccal cortical plate, and diameter of the LFC, and to attempt to find a relation between the data obtained to age, sex, and dental condition. Settings and Design: This study design involves a retrospective cross-sectional study. Methods: A total of 303 CBCT images were evaluated of the anterior mandible with software and recorded the measurements into a spreadsheet, which was converted into graphs and tables. The CBCTs were assessed based on sex, age, and dental condition. Statistical Analysis Used: Fisher’s exact test and Student’s t-test. Results: We found a prevalence rate of 99.3%. The foramina were evident in 102 (99.0%) men and 199 (99.5%) women. The most prevalent number of canals was two (47.5%). The superior canal presented as greater length (7.25 ± 2.04 mm) and diameter (0.95 ± 0.58 mm). Conclusion: The prevalence of LF is high, and their presence is not related to sex, age, or dental condition.

Keywords: Anterior mandible, cone-beam computed tomography, lingual foramina

How to cite this article:
de Andrade Santos JB, de Brito FC, e Mello Dias EC. Prevalence of lingual foramina in the anterior mandible: A cone-beam computed tomography study. J Oral Maxillofac Radiol 2020;8:10-5

How to cite this URL:
de Andrade Santos JB, de Brito FC, e Mello Dias EC. Prevalence of lingual foramina in the anterior mandible: A cone-beam computed tomography study. J Oral Maxillofac Radiol [serial online] 2020 [cited 2023 Mar 24];8:10-5. Available from: https://www.joomr.org/text.asp?2020/8/1/10/288833

Introduction

The anterior mandible is a clinically important region for surgical procedures such as dental extractions, bone graft donor area, and among others, dental implant installation.

Therefore, studies have shown bone alteration in the initial three or 6 months after dental extraction, followed by a gradual decrease in subsequent months.^[1]

Professionals should know the anatomy and morphology and carefully instrument this region, avoiding severe bleeding complications usually resulting due to arterial trauma associated with perforation of the lingual cortical plate or injury to the terminal branches of the sublingual and submental arteries that pierce the lingual cortical plate of the mandible toward the end of their course.^[2] Bleeding can occur immediately or later and may push the tongue back, subsequently causing occlusion of the airways.^[3]

Computed tomography (CT) is particularly important for preoperative planning in the field of implantology, as it allows a three-dimensional (3D) evaluation of bone ridges, which helps in the precise selection of the implant suitable for a bone dimension avoid critical structural injuries.^[4]

The aims of this study were to determine the prevalence of lingual foramina (LF) in the anterior mandible and to evaluate the presence and number of foramina, lengths of the LF canals (LFC), distance from the base of the mandible to the entrance of the LFC, distance from the base of the mandible to the end of the LFC, distance from the end of the LFC to the buccal cortical plate, diameters of the LFC, and to attempt to find a relation between the data obtained to age, sex, and dental condition through analysis of cone-beam CT (CBCT) scans.

Methods

We conducted this research after prior approval from the Research Ethics Committee for human subjects from the São Leopoldo Mandic Dental Research Center, under-report number 141620/2017.

We evaluated the medical records and CBCT scans of patients treated at the Implant Dentistry clinic at the São Leopoldo Mandic Graduate Center, advised for diagnostic purposes before implant or other oral surgical procedures. All patients who had their scans evaluated for this study signed an informed consent form before treatment, allowing their data to be used for research and for ensuring the confidentiality of all the information collected, including the patients’ identities.

The sample consisted of 303 CBCT scans advised between January 2015 and October 2015, which were analyzed by a single examiner in 2018.

The dependent variables were the presence and diameters of the LF and their positions in relation to the base of the mandible. The independent variables were age, sex, and dental condition of the region under evaluation.

We applied the following exclusion criteria for the selection of scans: scans with mandibular fractures; bone defects; tumors; and/or artifacts occurring due to the presence of metallic structures in the oral cavity, such as implants, screws used in block grafts, or fixation plates in cases of fracture.

All the scans were obtained from a single tomography unit, the I-CAT^® Next Generation (Imaging Sciences International, Hatfield, PA, USA). The protocol used for image acquisition was: 13 cm field-of-view, 120 kVp, and 12 mA; a time of 40 s for image acquisition with isotropic voxels; and 0.25 mm primary axial reconstructions.

We analyzed the reconstructed images using the I-CAT XoranCat^® software (Imaging Sciences International, Hatfield, Pennsylvania, USA), which were transaxial images with a thickness of 1 mm and were obtained at 1 mm intervals. We entered the measurements obtained from each tomographic image into a Microsoft^® Excel spreadsheet for Mac, © 2017 Microsoft, version 15.35 (170,610), Santa Rosa, Califórnia. Moreover, subsequently analyzed and converted them into graphs and tables.

Initially, data such as sex, age, the extent of edentulism, presence of bone canals (yes or no), and the number of canals (nonexistent, 1, 2, 3, or more canals) were obtained. We measured the distance of the entrance (M1) and the end (M2) of the canal from the base of the mandible, and the distance from the end of the canal to the buccal cortical plate (M3). If the image showed the presence of more than one canal, the measurements were individually obtained for each canal.

We also measured the canal length (M4) and the diameter of the canal at the entrance (M5) [Figure 1] and [Figure 2].

Figure 1: Image representing the measurements (a) M1, M2, M3; (b) M4; (c) M5

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Figure 2: Transaxial section of the mandibular central incisor region showing the lingual foramina and their measurements (a) M1, M2, M3, M4, and (b) M5

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In the statistical analysis, the sample of 303 conical beam CTs evaluated in this study was characterized by sex and age, in absolute (n), and relative (%) terms. The variables sex, age group, and dental condition were associated with the presence of lingual foramines through exact Fisher or G tests.

To investigate whether there was a difference between the sexes and between bites and toothless variables–distances from the beginning and end of the canal to the base of the mandible, canal distances to vestibular cortical, lengths, and diameters of the canal–were applied Student’s t tests. To verify whether these dependent variables were influenced by the age group, variance analyses were used, which were followed by Tukey multiple comparisons test.

Statistical calculations were conducted in SPSS 23 (SPSS INC., Chicago, IL, USA) and BioEstat 5.0 (Mamirauá Foundation, Belém, PA, Brazil), and the significance level of 5% was adopted.

Results

Of the 303 tomography scans, two scans did not show the presence of any foramina, while 301 scans did, indicating a prevalence rate of 99.3%. The foramina were evident in 102 (99.0%) males and 199 (99.5%) females.

After the determination of the prevalence rate, statistics pertaining to the foramina were performed only for patients, in whom LF were present, i.e., for 301 patients. [Figure 3] shows the most prevalent number of foramina in CBCT scans. The frequencies of the presence of foramina and the number of canals associated with independent variables such as sex, age, and dental condition are shown in [Table 1] and [Table 2].

Figure 3: Pie chart for the absolute (n) and relative (%) frequencies of the number of canals

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Table 1: Absolute (n) and relative (%) frequencies for the lingual foramina according to sex, age, and dental condition

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Table 2: Absolute (n) and relative (%) frequencies for the number of canals according to sex, age, and dental condition

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The means and standard deviations of the dependent variables are shown in [Table 3], [Table 4], [Table 5].

Table 3: Means and standard deviations for the distance from the entrance and the end of the canal to the base of the mandible, distance from the canal to the buccal cortical plate, and canal lengths and diameters according to sex

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Table 4: Means and standard deviations for the distance from the entrance and the end of the canal to the base of the mandible, distance from the canal to the buccal cortical plate, and canal lengths and diameters according to age group

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Table 5: Means and standard deviations for the distance from the entrance and the end of the canal to the base of the mandible, distance from the canal to the buccal cortical plate, and canal lengths and diameters according to a dental condition

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Discussion

Precise planning of surgical procedures in the mandibular midline requires careful measurement of the extent and evaluation of the 3D location of the genial plexus, considering factors that directly influence such measurements, such as sex, age, and the presence of dental elements.^[5]

Studies that utilized conventional and CBCT scans to assess the presence, diameter, distance, number, course, and communication of the associated endosseous canals have shown that CBCT is the fundamental examination required for adequate planning for implant placement in the anterior mandible. At the same time, these studies emphasized the importance of LF and their variations in preventing complications in dental implant procedures.^{[6],[7],[8],[9],[10],[11]}

In the present study, it was possible to locate and measure LF in 99.3% of the patients in the sample, which is similar to results obtained by other authors. Salinas-Goodier et al.^[12] found a prevalence of 96% for LF. Tepper et al.,^[13] Tagaya et al.,^[9] Babiuc et al.,^[14] and Abesi et al.^[15] observed a prevalence of 100% for LF. Romanos et al.^[16] found a prevalence of 86%. We detected some shortcomings in the results presented by Parnia et al.,^[4] who reported a prevalence of 49% and Kim et al.,^[17] who reported 58.8%. We noted that these authors aimed to measure the anatomical variations using CBCT in the interforaminal region, and not just in the symphyseal region, as was our study. They analyzed 96 and 187 images, respectively, and in both the studies, the number of scans of males was more. However, in our research, in addition to evaluating a considerably larger number of CBCT scans, we determined that sex is not associated with the presence of LF.

In our study, 47.5% of patients showed the presence of two canals, followed by the presence of a single canal (46.5%). The presence of three canals was determined in 6.0% cases, which is similar to the results presented by Abesi et al.^[15] There was no significant difference in the number of foramina between men and women, among age groups, or even between dentulous and edentulous subjects. Conversely, other authors have reported that single foramina are the most prevalent.^[14],[18]

The values observed in our research for distance from the entrance of the canal to the base of the mandible in relation to sex are close to the values observed in other studies, such as those by Tagaya et al.^[9] and Babiuc et al.^[14] One significant finding of our study was that the distance from the entrance of the superior canal to the base of the mandible was significantly shorter in edentulous subjects than that in dentulous subjects. For the middle and inferior canals, there were no differences in the distance from the entrance of the canals to the base of the mandible. However, the distance from the end of the canal to the base of the mandible, either for the superior, middle, or inferior canals, was not affected by dentulous state, corroborating the results by Alérico et al.,^[5] who also found no significant difference between men and women.

Considering the measurements made regarding the distance from the canal to the buccal cortex, this distance in edentulous teeth was shown to be significantly smaller in relation to dentates. A similar result also found in the work of Alérico et al.^[5] These data suggest about the bone remodeling caused by tooth loss that can lead to a horizontal reduction of the buccal wall, as shown by studies in humans, which describes a horizontal bone loss between 29% and 63% and vertical bone loss between 11% and 22% after 6 months of tooth extraction and still show rapid reductions in the first 3–6 months, followed by gradual reductions in the posterior dimensions.^[1]

As for the canal length, we observed that this distance was not influenced by the presence of teeth in the oral cavity. We noted an exception only for the length of the inferior canal, which was significantly greater among dentulous subjects. However, there was a significant difference among age groups while comparing the lengths of the superior and inferior canals. Significantly higher values were evident among individuals up to 30 years of age compared to those among individuals of 31–60 years of age. Nevertheless, neither of these two groups differed significantly from the group of individuals aged 61 years and above. The length of the LFC was >5 mm at all positions, confirming the results of the study by Soto et al.^[19] We also observed statistically greater length measurements in men than those in women, which confirm the results found by Sanchez-Perez et al.^[20] These results suggest the importance of the surgeon to evaluate and identify FL through the CBCT to decide the safety margin to intervene in this region.

We found a significant difference among age groups when comparing the diameters of the middle and inferior canals. The diameter of the middle canal did not differ when comparing the patients up to 30 years and patients of 31–60 years of age. For both the age groups, the values were significantly greater than those for subjects aged 61 years and more. As for the diameter of the inferior canal, we identified greater values in the up to 30 years of age group compared to those in 61 years and more age group. There was no significant difference between sexes in either the superior, middle, or the inferior canals. This result is similar to that observed by Jaju and Jaju.^[8] It is also observed in this study that, among the three canal found in the midline, the superior canal presented higher caliber, regardless of sex, age group, or dental condition. Fact also confirmed by the results of Tagaya et al.^[9] Where it reports that the midline location of the foramina is the most frequent and showed the most caliber, and among these, those located above the genial spines are the most common. The identification of the canal diameter is important to prevent complications during surgical procedures. LFC with diameters ≥1 mm must be preserved due to the risk of hemorrhages in the floor of the mouth.^[21]

The findings of this study demonstrate the importance of understanding the prevalence and anatomical variability of these structures. This knowledge and FL identification through the CBCT are crucial for planning surgeries in the anterior mandible, especially in the symphysis region, such as bone graft removal, orthognathic surgeries, and especially during rehabilitation with dental implants, to prevent potential hemorrhagic complications.

Conclusion

Based on the results of this study, we can state that LF is highly prevalent (99.3%) in the anterior mandible. Their presence is not associated with sex, age, or dental condition. This study demonstrated the importance of knowledge regarding the location and distances of LF in relation to various anatomical landmarks present in the symphysis region for planning surgeries in the anterior mandibular region, especially in rehabilitation with dental implants, thereby preventing potential complications such as hemorrhages.

Acknowledgment

The authors would like to thank Editage (www.editage.com) for publication support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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