1. Introduction
umerous surgeries are performed on the anterior region of the lower jaw (the area between two chin holes). Furthermore, the location of the chin hole (Mental Foramen; MF) is critical in multiple cases, like anesthesia injection and periapical surgeries in the anterior lower jaw. Besides, the diversity in the location and position of this hole can generate problems during surgery in this region.
2. Materials and Methods
In this study, 450 panoramic radiographic images of men and women were evaluated. All images were converted to JPEG format and entered in real size in Auto CAD software (2014). Data analysis was performed in SPSS using one-way Analysis of Variance (ANOVA), Student’s t-test, and Chi-squared tests.
3. Results
The mean distance from the MF to the lower edge of the mandible on the right and the left were equal to 10.53 mm and 10.51 mm, respectively. The mean distance from the MF to the posterior side of the lower jaw was measured as 49.36 mm on the right and 48.72 mm on the left. Additionally, the mean distance of this hole to the midline of the lower jaw on the right and left was 27.16 and 26.27 mm, respectively. In most explored cases, the anterior-posterior position of this hole was symmetrical concerning anatomical landmarks. The anterior-posterior distance of MF to the lower jaw midline presented significant gender-wise differences (P<0.001). The shape of the MF provided no gender-wise significant difference (P=0.89) (Table 1 & 2 & 3). 






4. Discussion and Conclusion
The current research results suggested that the most frequent anterior-posterior position of the MF is located between the apex of the first and second premolars. Furthermore, the most prevalent shape of the MF using panoramic images was oval. According to the data obtained in the present study and other investigations, the shape of the MF in the offending population was mainly oval. In general, the differences in the location and position of the MF in this research, compared to other studies can be attributed to morphological and anthropological variations in various populations.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of Hormozgan University of Medical Sciences (Code: IR.HUMS.REC.1394.189).

Funding
This article is extracted from the MD. dissertation of dental dentistry of the first author at the Department of Endodontics, School of Dental, Shahid Sadoughi University of Medical Sciences, Yazd.

Authors' contributions
Conceptualization and supervision: Masoumeh Afsa; Data collection, Writing – original draft: Hamzeh Ekran; Data analysis, writing – review & editing: Amin Ghanbarnejad.

Conflicts of interest
The authors stated no conflicts of interest.

Acknowledgements
We would like to thank all Staff of Hormozgan University of Medical Sciences and all the staff and colleagues of the School of Dentistry, Department of Radiology who contributed to this research.


References

1. Iwanaga J, Saga T, Tabira Y, Nakamura M, Kitashima S, Watanabe K, et al. The clinical anatomy of accessory mental nerves and foramina. Clin Anat. 2015; 28(7):848-56. [DOI:10.1002/ca.22597] [PMID]
2. Loudon J. Beware the mental foramen. Br Dent J. 2011; 210(7):293. [DOI:10.1038/sj.bdj.2011.249] [PMID]
3. Udhaya K, Saraladevi KV, Sridhar J. The morphometric analysis of the mental foramen in adult dry human mandibles: A study on the South Indian population. J Clin Diagn Res. 2013; 7(8):1547-51. [DOI:10.1038/sj.bdj.2011.249] [PMID]
4. Al-Juboori MJ, Hua CM, Yuen KY. The importance of the mental foramen location detection by using different radiographic technique: Mini review. International J Med Imaging. 2014; 2(3):63-8. [DOI:10.11648/j.ijmi.20140203.14]
5. Zmysłowska-Polakowska E, Radwański M, Łęski M, Ledzion S, Łukomska-Szymańska M, Polguj M. The assessment of accessory mental foramen in a selected polish population: A CBCT study. BMC Med Imaging. 2017; 17(1):17. [DOI:10.1186/s12880-017-0188-6] [PMID] [PMCID]
6. Aminoshariae A, Su A, Kulild JC. Determination of the location of the mental foramen: A critical review. J Endod. 2014; 40(4):471-5. [DOI:10.1016/j.joen.2013.12.009] [PMID]
7. Chappidi V, Swapna LA, Dheeraj V, Nikitha GR, Kanakagiri M. Evaluation of morphometric variations in mental foramen and prevalence of anterior loop in South Indian population: A CBCT study. J Indian Acad Oral Med Radiol. 2019; 31(2):134-9. [DOI:10.4103/jiaomr.jiaomr_219_18]
8. Alok A, Singh ID, Singh S. Evaluation of styloid process in bareilly population on digital panoramic radiographs. J Indian Acad Oral Med Radiol. 2016; 28(4):381-5. [DOI:10.4103/0972-1363.200623]
9. Cakur B, Dagistan S, Shahin A, Haroli A, Yilmaz A. Reliability of mandibular cortex index and mandibular bone mineral density in the detection of osteoporotic women. Dentomaxillofac Radiol. 2009; 35(5):255-61. [DOI:10.1259/dmfr/22559806] [PMID]
10. Cakur B, Sahin A, Dagistan S, Altun O, Caglayan F, Miloglu O, et al. Dental panoramic radiography in diagnosis of osteoporosis. J Int Med Res. 2008; 36(4):792-9. [DOI:10.1177/147323000803600422] [PMID]
11. Mraiwa N, Jacobs R, van Steenberghe D, Quirynen M. Clinical assessment and surgical implications of anatomic challenges in the anterior mandible. Clin Implant Dent Relat Res. 2003; 5(4):219-25. [DOI:10.1111/j.1708-8208.2003.tb00204.x] [PMID]
12. Jacobs R, Mraiwa N, vanSteenberghe D, Gijbels F, Quirynen M. Appearance, location, course, and morphology of the mandibular incisive canal: An assessment on spiral CT scan. Dentomaxillofac Radiol. 2002; 31(5):322-7. [DOI:10.1038/sj.dmfr.4600719] [PMID]
13. Tözüm TF, Taguchi A. Role of dental panoramic radiographs in assessment of future dental conditions in patients with osteoporosis and periodontitis. N Y State Dent J. 2004; 70(1):32-5. [PMID]
14. Niknami M, Esmaeeli F, Nazer A. [Radiographic evaluation of location and shape of mental foramen in selective Iranian Population (Persian)]. Res Dent Sci. 2011; 8(2):102-8. http://jrds.ir/article-1-46-en.pdf
15. Ziegler CM, Woertche R, Brief J, Hassfeld S. Clinical indications for digital volume tomography in oral and maxillofacial surgery. Dentomaxillofac Radiol. 2002; 31(2):126-30. [DOI:10.1038/sj.dmfr.4600680] [PMID]
16. Miracle AC, Mukherji SK. Conebeam CT of the head and neck, part 1: Physical principles. AJNR Am J Neuroradiol. 2009; 30(6):1088-95. [DOI:10.3174/ajnr.A1653] [PMID] [PMCID]
17. Muinelo-Lorenzo J, Suárez-Quintanilla JA, Fernández-Alonso A, Varela-Mallou J, Suárez-Cunqueiro MM. Anatomical characteristics and visibility of mental foramen and accessory mental foramen: Panoramic radiography vs. Cone beam CT. Med Oral Patol Oral Cir Bucal. 2015; 20(6): e707-14. [DOI:10.4317/medoral.20585] [PMID] [PMCID]
18. Naitoh M, Yoshida K, Nakahara K, Gotoh K, Ariji E. Demonstration of the accessory mental foramen using rotational panoramic radiography compared with cone-beam computed tomography. Clin Oral Implants Res. 2011; 22(12):1415-9. [DOI:10.1111/j.1600-0501.2010.02116.x] [PMID]
19. Sukovic P. Cone beam computed tomography in craniofacial imaging. Orthod Craniofac Res. 2003; 6 (Suppl 1):31-6. [DOI:10.1034/j.1600-0544.2003.259.x] [PMID]
20. Falk A, Gielen S, Hauser L. CT data acquisition as a basic for modern diagnosis and therapy in Maxillofacial surgery. Int J Oral Maxillofac Surg. 1995; 24(1):69-75. [DOI:10.1016/S0901-5027(05)80865-3]
21. Abed HH, Bakhsh AA, Hazzazi LW, Alzebiani NA, Nazer FW, Yamany I, et al. Anatomical variations and biological effects of mental foramen position in population of Saudi Arabia. Dentistry. 2016; 6(4):373. https://www.researchgate.net/profile/Abdulaziz-Bakhsh/publication/301898976_Anatomical_Variations_and_Biological_Effects_of_Mental_Foramen_Position_in_Population_of_Saudi_Arabia/links/572c605808ae0a72918a4215/Anatomical-Variations-and-Biological-Effects-of-Mental-Foramen-Position-in-Population-of-Saudi-Arabia.pdf
22. Gungor K, Ozturk M, Semiz M, Brooks SL. A radiographic study of location of mental foramen in a selected Turkish population on panoramic radiograph. Coll Antropol. 2006; 30(4):801-5. [PMID]
23. Alshayyab MH, Alsoleihat F, DarOdeh NS, Ryalat S, Baqain ZH. The mental foramen I: Radiographic study of the anteriorposterior position and shape in Iraqi population. Int J Morphol. 2015; 33(1):149-57. [DOI:10.4067/S0717-95022015000100024]
24. Chkoura A, El Wady W. Position of the mental foramen in a Moroccan population: A radiographic study. Imaging Sci Dent. 2013; 43(2):71-5. [DOI:10.5624/isd.2013.43.2.71] [PMID] [PMCID]
25. Kumar V, Hunsigi P, Kaipa BR, Reddy R, Ealla KK, Kumar CB, Prasanna MD. Radiographic localization of mental foramen in Northeast and South Indian ethnic groups of Indian population. J Contemp Dent Pract. 2014; 15(6):766-9. https://www.thejcdp.com/doi/pdf/10.5005/jp-journals-10024-1614
26. Al-Mahalawy H, Al-Aithan H, Al-Kari B, Al-Jandan B, Shujaat S. Determination of the position of mental foramen and frequency of anterior loop in Saudi population: A retrospective CBCT study. Saudi Dent J. 2017; 29(1):29-35. [PMID] [PMCID]
27. Muhammad DA. Anteroposterior position of the mental foramen on panoramic radiographs in Sulaimani population. Kurdistan Acad J. 2009; 8:9-16. [Link not Found]
28. Tafakhori Z, Karimi M. [Evaluation of horizontal position of mental foramen in relation to mandibular premolar in the panoramic radiograph in Rafsanjan City in 2014 (Persian)]. J Rafsanjan Univ Med Sci. 2016; 14(11):913-22. http://journal.rums.ac.ir/article-1-2633-en.html
29. Haghanifar S, Rokouei M. Radiographic evaluation of the mental foramen in a selected Iranian population. Indian J Dent Res. 2009; 20(2):150-2. [DOI:10.4103/0970-9290.52886] [PMID]
30. Kqiku L, Sivic E, Weiglein A, Städtler P. Position of the mental foramen: An anatomical study. Wien Med Wochenschr. 2011; 161(9-10):272-3. [DOI:10.1007/s10354-011-0898-2] [PMID]
31. Singh, R, Srivastav, AK. Study of position, shape, size and incidence of mental foramen and accessory mental foramen in Indian adult human skulls. Int J Morphol. 2010; 28(4):1141-6. [DOI:10.4067/S0717-95022010000400025]
32. Prabodha LB, Nanayakkara BG. The position, dimensions and morphological variations of mental foamen in mandibles. Galle Med J. 2006; 11(1):13-5. [DOI:10.4038/gmj.v11i1.1111]
33. Nanayakkara D, Sampath H, Manawaratne R, Peiris R, Vadysinghe A, Arambawatte K. Positional variation and localization of the mental foramen. MOJ Anat Physiol. 2018; 5(1):39‒44. [DOI:10.15406/mojap.2018.05.00162]