The mandible is the largest and strongest bone of the facial skeleton and plays a pivotal role in mastication, speech, and facial aesthetics. Within its structure lies the mandibular canal (MC), also known as the inferior alveolar canal, which transmits the inferior alveolar nerve, artery, and vein. The canal begins at the mandibular foramen on the medial aspect of the ramus and extends anteriorly within the body of the mandible, terminating at the mental foramen (MF).

The mental foramen is located on the external surface of the mandibular body and serves as the exit point for the mental nerve and vessels. It is typically located near the premolar region; however, considerable positional variation has been reported. Such variability may influence the success of regional anesthesia, implant placement, endodontic treatment, periapical surgery, and orthognathic procedures.

In modern dental practice, panoramic radiography (orthopantomogram – OPG) is widely utilized for

diagnostic evaluation due to its broad coverage, low radiation dose, and cost-effectiveness. Digital imaging systems have further enhanced measurement accuracy and reproducibility.

Several studies have reported ethnic and regional differences in the morphology and position of the mandibular canal and mental foramen. South Indian populations, particularly those from Telangana, have not been extensively studied in this regard. Therefore, region-specific data are essential to avoid surgical complications such as inferior alveolar nerve injury, paresthesia, hemorrhage, or implant failure.

This study was undertaken to analyze the morphological and morphometric characteristics of the mandibular canal and mental foramen in a South Indian population using digital OPGs.

Aims: To determine the course, length, and shape of the mandibular canal. To evaluate the shape, position, and morphometric location of the mental foramen.

This is a Retrospective and cross-sectional radiographic study. Ethical Approval Approval was obtained from the Institutional Ethics Committee of Shadan Institute of Medical Sciences & Research Centre (EC/NEW/INST/2023/4198). Sample Size 400 clear digital orthopantomograms (OPGs) were selected. Study Population Radiographs were collected from V.S. Diagnostic Centre, Suncity, Hyderabad, Telangana over 4–5 months. Age Groups • Group A: 20–40 years • Group B: 41–75 years Both dentulous and edentulous individuals were included. Inclusion Criteria • High-quality digital OPGs • Clear visibility of mandibular canal borders • Clear identification of mental foramen • Age between 20–75 years Exclusion Criteria • History of mandibular fractures • Orthognathic surgery • Orthodontic treatment • Severe mandibular growth retardation • Unclear anatomical landmarks Measurement Technique All radiographs were taken using Digital X-ray Imaging System Model PCH-30 CS. Measurements were made using E-Soft Dent 2.0 software (Vatech machine). Parameters Measured 1. Distance from alveolar crest to center of mental foramen 2. Distance from center of mental foramen to inferior border of mandible 3. Distance from mental foramen to symphysis menti 4. Shape of mental foramen 5. Course and shape of mandibular canal 6. Length of mandibular canal Statistical Analysis Software used: SPSS version 26.0 • Frequencies and percentages for qualitative data • Mean and Standard Deviation for quantitative data • Kolmogorov–Smirnov test for normality • Mann–Whitney U test for non-parametric comparisons • Chi-square test for association • Significance level: p < 0.05

A total of 400 mental foramina were evaluated using orthopantomograms (OPG). The study population was divided into two age groups:

• Group A: 20–40 years
• Group B: 41–75 years

The morphometric parameters were analyzed bilaterally (Right and Left sides).

Table 1: Age Group Distribution of Study Population

The majority of mental foramina evaluated belonged to Group A (20–40 years) constituting 54.5% of the study population, whereas Group B (41–75 years) accounted for 45.5%. The distribution shows slightly higher representation of younger individuals in the present study.

Table 2: Gender Distribution of Study Population

Out of 400 mental foramina evaluated, 203 (50.7%) were from males and 197 (49.3%) were from females. The gender distribution in the present study was nearly equal, showing no significant gender predominance.

Table 3. Distance from Alveolar Crest to the Centre of Mental Foramen

The mean distance was higher in Group A compared to Group B. A reduction in vertical height in Group B suggests possible age-related alveolar bone resorption.

Table 4. Distance from Centre of Mental Foramen to Inferior Border of Mandible

Group B showed slightly increased distance from the inferior border. This may indicate relative superior repositioning of the foramen due to alveolar bone loss with aging.

Table 5. Distance from Mental Foramen to Symphysis Menti

The horizontal distance from symphysis menti was slightly greater in younger individuals. The difference between sides was minimal, suggesting bilateral symmetry.

Table 6: Shape of Mental Foramen – Right Side

On the right side, the mental foramen was predominantly round in shape (98.5%), while only 1.5% were oval. This indicates that the round configuration is the most common morphological presentation of the mental foramen in the present study population.

Table 7: Shape of Mental Foramen – Left Side

On the left side, the mental foramen was predominantly round (98.5%), with only 1.5% presenting an oval shape. The mental foramen was predominantly round in shape on both right and left sides (98.5%), while only 1.5% were oval. No significant side-wise variation was observed.

Table 8: Right Side – Shape Distribution by Age Group

Table 9: Distribution of Shape of Mental Foramen (Right) According to Age Group

In Group A (20–40 years), 98.6% were round, while in Group B (41–75 years), 98.4% were round. Only 1.4% and 1.6% were oval in Group A and Group B respectively. The distribution indicates no significant age-related variation in shape of the mental foramen on the right side.

Table 10: Distribution of Shape of Mental Foramen (Left) According to Age Group

Table 11: Comparison of Morphometric Measurements of Mental Foramen (Right Side) Between Genders – Mann-Whitney U Test

There was a statistically significant difference in horizontal distance between males and females on the right side (p < 0.05). Males showed higher mean rank values, indicating greater horizontal measurements compared to females.

Table 12: Distance from Mental Foramen to Inferior Border of Mandible (Right)

Table 13: Distance from Mental Foramen to Alveolar Crest (Right)

The Mann-Whitney U test revealed statistically significant gender differences in all three morphometric parameters on the right side (p < 0.05). Males demonstrated greater measurements in horizontal distance, inferior border distance, and alveolar crest distance compared to females.

Table 14: Comparison of Morphometric Measurements of Mental Foramen (Left Side) Between Genders – Mann-Whitney U Test

A statistically significant difference was observed between males and females (p < 0.05). Males showed higher mean rank values, indicating greater horizontal distance compared to females.

Table 15: Distance from Mental Foramen to Inferior Border of Mandible (Left)

There was a statistically significant difference between genders (p < 0.05), with males demonstrating greater distance from the inferior border.

Table 16: Distance from Mental Foramen to Alveolar Crest (Left)

The Mann-Whitney U test revealed statistically significant gender differences in all morphometric parameters on the left side (p < 0.05). Males consistently demonstrated greater measurements compared to females.

Table 17: Distribution of Shape of Mandibular Canal

The elliptical shape was the most common configuration of the mandibular canal, observed in 64.5% of cases. The linear shape was seen in 23.8% of cases, while spoon-shaped (5.8%) and turning curve (6.0%) patterns were comparatively less common. These findings suggest that the elliptical configuration predominates in the Telangana population, with other morphological variations occurring less frequently. The elliptical type was the predominant morphological pattern of the mandibular canal (64.5%), followed by linear type (23.8%), whereas spoon-shaped and turning curve configurations were relatively uncommon.

The present study evaluated the morphometric characteristics and positional variations of the mental foramen and mandibular canal in a Telangana population using orthopantomograms (OPG). The findings provide valuable anatomical data with clinical implications for local anesthesia, implant placement, endodontic surgery, and maxillofacial procedures.

In the present study, the majority of cases belonged to the 20–40 years age group (54.5%). Age-related differences were more evident in vertical measurements rather than horizontal parameters. The reduction in distance from alveolar crest to mental foramen in the older age group suggests alveolar bone resorption associated with aging.

Similar findings were reported by Eddowes et al. (2019) and Gogoi et al. (2018), who observed that vertical bone height decreases with advancing age due to physiological bone remodeling. Age-related superior repositioning of the mental foramen has also been documented in panoramic radiographic studies.

However, no significant association between age and shape of mental foramen was observed in our study (p > 0.05). This finding aligns with studies by Gungor et al. and Al-Khateeb et al., who reported morphological stability of mental foramen across age groups.

This finding is strongly supported by Gupta et al. (2015), Alenezi et al. (2018), and Singh et al. (2020), who similarly reported the second premolar region as the most common location of the mental foramen in their respective populations. Most global studies indicate that the mental foramen is predominantly positioned below the apex of the second premolar; however, certain African and Middle Eastern populations have demonstrated greater positional variability. The consistency observed in the Telangana population in the present study suggests predictable anatomical localization of the mental foramen, which is clinically advantageous during mental nerve block administration, implant placement, and other surgical interventions in the premolar region.

The present study also demonstrated that the mental foramen was predominantly round in shape (98.5%) on both sides, with only 1.5% showing an oval configuration. This predominance of the round shape is slightly higher compared to the findings of Sekerci et al. (2017), who reported round morphology in 72–85% of cases, and Al-Khateeb et al. (2015), who observed round shapes in approximately 80–90% of cases. The minimal morphological variation noted in the present study indicates a high degree of anatomical uniformity within the studied regional population.

Furthermore, the elliptical configuration (64.5%) was identified as the most common shape of the mandibular canal, followed by the linear type (23.8%), whereas spoon-shaped and turning curve patterns were relatively uncommon. Similar observations were reported by Angelopoulos et al. (2016) and Choi et al. (2018), who also found elliptical canal morphology to be predominant in Asian populations. These variations in mandibular canal morphology are clinically significant, as curved or spoon-shaped canals may increase the risk of inferior alveolar nerve injury during implant drilling and other surgical procedures. Therefore, careful radiographic assessment is essential to minimize procedural complications.

Accurate localization=MF local anesthesia and it would assist maxillofacial surgeons. The elliptic arcs, spoon-shaped are the most secure and favorable anteroposterior course of mandibular canal for rehabilitative and surgical interventions due to the availability of "safe" space. Most of the canals (51.7 %) are in the high-risk zone (high and low canals), and females had a higher percentage of high canals than males, caution must be exercised during procedures like extractions, disimpactions, or root canal therapy in the mandibular 3rd molars to avoid injuries to the inferior alveolar canal. Acknowledgment The author expresses gratitude to Prof. & HOD Dr. T. Sreekanth, Dr. Sanjay Kumar Sharma, Dr. Arvind Kumar Pankaj, and Dr. Apurba Patra for their academic support.

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