Radiographic Study of Mental Foramen Type and Position in Bangalore Population Navya N

Journal of Medicine, Radiology, Pathology & Surgery (2015), 1, 5–8

ORIGINAL ARTICLE

Radiographic study of mental foramen type and position in Bangalore population Navya N. Swamy, Tejavathi Nagaraj, Noori Ghouse, C. D. Jagadish, N. Sreelakshmi, Rahul Dev Goswami

Department of Oral Medicine and Radiology, Sri Rajiv Gandhi Dental College & Hospital, Bengaluru, Karnataka, India

Keywords Abstract Mandibular canal, mental foramen, Background: The mental foramen is defined as the entire funnel-like opening in the panoramic radiograph lateral surface of the mandible at the terminus of the mental canal. The mental foramen

Correspondence marks the termination of mandibular canal in the mandible, through which the inferior Dr. Navya N. Swamy, Department of alveolar nerve and vessels pass. Position of the mental foramen is important when Oral Medicine and Radiology, Sri Rajiv administering regional anesthesia. The aim of this study was to determine the most Gandhi Dental College and Hospital, common type and position of mental foramen in Bangalore population using digital Cholanagar, Bengaluru - 560 032, panoramic radiographs. Karnataka, India. Phone: +91-9686633552, Materials and Methods: A total of 100 (50 M and 50 F) digital panoramic radiographs Email: [email protected] were collected from Department of Oral Medicine and Radiology within age of 15‑50 years, type and position of mental foramen was analyzed. Received 03 November 2014; Results: The most common occurrence is Type I and position 4 (symmetrical) of mental Accepted 29 December 2014 foramen. Comparison of type in males and females appears significant. Comparison of the position in males and females appears not significant. doi: 10.15713/ins.jmrps.2 Conclusion: The following study suggests that clinicians should carefully identify mental foramen thus minimizing complications during implant, orthognathic surgery and treatment of maxillofacial injuries.

Introduction

Knowing the location of the mental foramen is very important when considering placing implants or any other surgical procedure in the foraminal region.[1] Mental foramen is a small foramen situated in the anterolateral aspect of the body of the mandible.[2] The mental foramen is defined as the entire funnel-like opening in the lateral surface of the mandible at the terminus of the mental canal [Figure 1].[3] This foramen is contained entirely within the buccal cortical plate of bone. The average size of the foramen is 4.6 mm horizontally and 3.4 mm vertically Figure 1: Orthopantomogram showing type and position of mental on the lateral surface of the mandible.[4] The foramen is usually foramen larger on the left side of the mandible.[5] Schaeffer stated that mental foramen was located between the spaces of mandibular foramen and supply sensory innervations to the soft tissues premolars.[6] of the chin, lower lip and gingival on the ipsilateral side of the [8] Mental foramen`s anatomical position is of significant mandible. importance in giving local anesthesia, treatments of fractures Yosue and Brooks classified into four types[9] related to parasymphysis area, osteotomies required for orthognathic and implant placement, giving complete denture in Type I: Mental canal is continuous with the mandibular canal. mandible etc.[7] Inferior alveolar nerve gives mental and incisive Type II: The foramen is distinctly separated from the mandibular branch inside the canal. Mental nerve emerges from mental canal.

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Type III: Diffuse with a distinct border of the foramen. Chi-square test. The most common Type I is mental canal Type IV: “Unidentified group.” is continuous with the mandibular canal of mental foramen (53.5%), followed by Type III diffuse with a distinct border of The position of the image of the mental foramen was the foramen (31.5%), Type II the foramen is distinctly separated recorded as follows[9] from the mandibular canal (14.0%) Type IV unidentified group Position 1: Situated anterior to the first premolar. (1%) [Table 1]. Position 2: In line with the first premolar. The most frequent position 4 is in line with second premolar Position 3: Between the first and second premolar. of mental foramen (63.5%). The second common position Position 4: In line with second premolar. was position 3 between first and second premolar (23.0%) Position 5: Between the second premolar and first molar. followed by position 5 between the second premolar and first Position 6: In line with the first molar. molar (9.0%), position 2, in line with the first premolar (3.5%), The accurate identification of the mental foramen is important position 1 situated anterior to the first premolar, position 6 in for both diagnostic and clinical procedures. The radiographic line with the first molar (0%) Table[ 2]. appearance of the mental foramen may result in a misdiagnosis Comparison of type in males and females appears significant. of a radiolucent lesion in the apical area of mandibular premolar Comparison of the position in males and females appears not teeth.[10] Hence, the aim of this study was to determine the most significant. Sex analysis showed a higher female percentage of common type and position of mental foramen in Bangalore 60% in Type I [Graph 1]. Sex analysis showed a higher female population using digital panoramic radiographs. percentage of 84% in position 4 [Graph 2].

Materials and Methods Discussion Mental foramen is a key factor in many of the surgical as well Total of 100 (50 M and 50 F) digital panoramic radiographs were as clinical procedures in routine clinical practice.[11] Mental collected from Department of Oral Medicine and Radiology foramen represents the termination of the mental canal.[12] The within age of 15-50 years who were advised for radiographs mental nerve passes through the mental foramen, supplying for various purposes, ethical clearance was obtained. Type sensory innervation to the lower lip, buccal vestibule, and gingiva and position of mental foramen was analyzed. All panoramic mesial to the first mandibular molar.[13] The mental foramen has radiographs were taken by Sirona panoramic machine. The been reported to vary in position in different ethnic groups.[14] magnification factors reported by the manufacturers were 1.2 Knowing the site of the mental foramen allows for accurate and 1.25, respectively. delivery of local anesthesia of terminal incisive branches The radiographs were chosen according to the following of the inferior alveolar nerve. The mental bundle can be criteria traumatized during surgical procedures, such as periapical Inclusion criteria Table 1: Distribution of type in males and females • All mandibular teeth from the right first molar to the left first Type Gender (n (%)) Total χ2 P value molar were present Male Female n (%) • Erupted teeth 1 46 (46.0) 61 (61.0) 107 (53.5) 9.976 0.019** • The films must be free from any radiolucent or radiopaque 2 13 (13.0) 15 (15.0) 28 (14.0) lesion in the lower arch and showed no radiographic exposure 3 41 (41.0) 22 (22.0) 63 (31.5) or processing artifacts. 4 0 (0.0) 2 (2.0) 2 (1.0) Exclusion criteria Total 100 (100.0) 100 (100.0) 200 (100.0) • Radiographs in which the lower teeth (between 36 and 46) **Significant were missing, had deep caries, root canal treatment or various restorations were eliminated because of a possible associated Table 2: Distribution of position in males and females periapical radiolucency Gender (n (%)) Total χ2 P value • Radiographs that showed the lower canine was missing were Male Female n (%) excluded because of the possibility of mesial premolar drift 2 (2.0) 0 (0.0) 2 (1.0) 4.296 0.371* • Panoramic radiographs in which the mental foramen could 2 (2.0) 5 (5.0) 7 (3.5) not be identified were excluded. 22 (22.0) 24 (24.0) 46 (23.0) 63 (63.0) 64 (64.0) 127 (63.5) Results 11 (11.0) 7 (7) 18 (9) In 100 panoramic radiographs of mental foramen, most common 100 (100) 100 (100) 200 (100) type and position was studied and recorded by performing *Not significant

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This position is consistent with findings of Yosue and Brooks[4] in relation to types of mental foramen and in relation to 0« [21] [22] )« position Agarwal and Gupta, Prabodha and Nanayakkara [23] [2] Neo and Gupta and Soni. The same position was observed in Tanzanian adult black male,[24] Malay population[9] Brazilian,[25] Sankar et al.,[26] Malawian mandible,[27] Ukoha[28] in south eastern Nigerian Singh et al.[29] and Kanta et al. Jasser and Nwoku observed most common position as in line with the longitudinal axis of second premolar closely followed by location between first and second premolar in graph radio ic [30] study of Saudi Arabians. Panoramic radiographs were used in this study because the mental foramen was seen more consistently on the wide field 7\SHV of view in panoramic radiographs of the mandible than on periapical radiographs. A weakness of our study is the use of Graph 1: Distribution of types in male and female panoramic radiographs for localization of the mental foramen instead of the use of an anatomic study on skulls. panoramic radiographs showed a greater displacement of the foramen 0« compared with anatomical measurements; however, the )« difference in the horizontal position found by the two methods was not statistically significant. Further anatomical studies using skulls should be conducted in a Bangalore population. The limitations of this study are small sample size. A larger sample size would also enable a more detailed assessment of the position and type of mental foramen. Conclusion The present study reveals valuable insights on the information 3RVLWLRQ concerning the type and position of mental foramen in Bangalore population. The following study suggests that Graph 2: Distribution of position in male and female clinicians should carefully identify mental foramen thus minimizing complications during implant, orthognathic surgery surgery, extraction of impacted teeth, enucleation of cyst or and treatment of maxillofacial injuries. Hence, our study may tumor, and so on, resulting in paresthesia or anesthesia in the provide the necessary data of mental foramen among population area innervated by the nerve.[15] It also aids in interpreting and may be useful for the surgeons, anesthetists, neurosurgeons anatomical landmarks in oral pathology and forensics.[16] and dentists to carry out procedures without complications. Although it is often possible to identify the mental foramen radiographically, knowing the normal range of possible Clinical significance locations is essential. The location of the mental foramen has [9] Position of the mental foramen is important when administering been studied in different populations. regional anesthesia. Mental foramen identification and In our study, out of 100 panoramic radiographs, the preservation of mental nerve during. most common Type I is mental canal is continuous with the • Periapical surgery mandibular canal of mental foramen (53.5%) followed by • Implant surgery Type III diffuse with a distinct border of the foramen (31.5%). • Maxillofacial trauma The most common position for the mental foramen was in line • Orthognathic procedures. with the second premolar in 63.5%, followed by between the first and second premolars in 23.0%; thus these two positions accounted for 86.5% of the cases. References Our results were in accordance with previous studies in other 1. Al-Juboori MJ, Hua CM, Yuen KY. The importance of the mental populations showing that the most common type for the mental foramen location detection by using different radiographic foramen is continuous with the mandibular canal followed by technique: Mini review. Int J Med Imaging 2014;2:63-8. [4] diffuse with distinct border of foramen and in a position aligned 2. Gupta S, Soni JS. Study of anatomical variations and incidence with the second premolar, followed by a position between the of mental foramen and accessory mental foramen in dry human first and second mandibular premolars.[17-20] mandibles. Natl J Med Res 2012;2:28-30.

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3. Muhammad DA. Anteroposterior position of the mental from statistical observations. Int J Orthod Oral Surg Radiogr foramen on panoramic radiographs in Sulaimani population. 1927;13:299-305. Kurdistan Acad J 2009;8:9-16. 19. Tebo HG, Telford IR. An analysis of the variations in position of 4. Yosue T, Brooks SL. The appearance of mental foramina on the mental foramen. Anat Rec 1950;107:61-6. panoramic and periapical radiographs. II. Experimental 20. Mwaniki DL, Hassanali J. The position of mandibular and evaluation. Oral Surg Oral Med Oral Pathol 1989;68:488-92. mental foramina in Kenyan African mandibles. East Afr Med J 5. Yosue T, Brooks SL. The appearance of mental foramina on 1992;69:210-3. panoramic radiographs. Experimental evaluation. Oral Surg 21. Agarwal DR, Gupta SB. Morphometric analysis of mental Oral Med Oral Pathol 1989;68:488-92. foramen in human mandibles of South Gujarat. People’s J Sci 6. Rai R, Shrestha S, Jha S. Mental foramen: A morphological and Res 2011;4:15-8. morphometrical study. Int J Healthc Biomed Res 2014;2:144-50. 22. Prabodha LB, Nanayakkara BG. The position, dimensions and 7. Aher V, Pillai P, Ali FM, Mustafa M, Ahire M, Mudhol A, et al. morphological variations of mental foramen in mandible. Galle Anatomical position of mental foramen: A review. Glob J Med Med J 2006;11:13-5. Public Health 2012;1:61-4. 23. Neo J. Position of the mental foramen in Singaporean Malays 8. Roy PP, Ambali MP, Doshi MA, Jadhav SD. Variation in the and Indians. Anesth Prog 1989;36:276-8. position shape and direction of mental foramen in dry mandible. 24. Fabian FM. Position, shape and direction of opening of the Int J Anat Res 2014;2:418-20. mental foramen in dry mandibles of Tanzanian adult black 9. Ngeow WC, Yuzawati Y. The location of the mental foramen in a males. Ital J Anat Embryol 2007;112:169-77. selected Malay population. J Oral Sci 2003;45:171-5. 25. Maise MA, Felippe BP. The mental foramen position in 10. Phillips JL, Weller RN, Kulild JC. The mental foramen: 1. Size, dentate and edentulous Brazilian’s mandible. Int J Morphol orientation, and positional relationship to the mandibular 2008;26:981 7. second premolar. J Endod 1990;16:221-3. 26. Sankar DK, Bhanu SP, Susan PJ. Morphometrical and 11. Seema S, Bhavana D, Kamlesh T, Penci CA. Morphometric morphological study of mental foramen in dry dentulous analysis of mental foramen in human mandibles of Gujarat mandibles of South Andhra population of India. Indian J Dent region. Int J Sci Res 2014;3:36-7. Res 2011;22:542-6. 12. Green RM. The position of the mental foramen: A comparison 27. Igbigbi PS, Lebona S. The position and dimensions of the between the southern (Hong Kong) Chinese and other mental foramen in adult Malawian mandibles. West Afr J Med ethnic and racial groups. Oral Surg Oral Med Oral Pathol 2005;24:184-9. 1987;63:287‑90. 28. Ukoha UU. Position, shape and direction of the mental 13. Moiseiwitsch JR. Position of the mental foramen in a North foramen in mandibles South-Eastern Nigeria. Int J Biomed Res American, white population. Oral Surg Oral Med Oral Pathol 2013;4:499-503. Oral Radiol Endod 1998;85:457-60. 29. Singh SK, Gopinathan K. Variation in position and number of 14. Koppe T. Summary of: A comparative anthropometric study mental foramen in mandibles of north Indian population J Anat of the position of the mental foramen in three populations. Br Soc India 1992;41:47-51. Dent J 2012;212:188-9. 30. al Jasser NM, Nwoku AL. Radiographic study of the mental 15. Haghanifar S, Rokouei M. Radiographic evaluation of the foramen in a selected Saudi population. Dentomaxillofac Radiol mental foramen in a selected Iranian population. Indian J Dent 1998;27:341-3. Res 2009;20:150-2. nd 16. Shankland WE 2 . The position of the mental foramen in Asian How to cite this article: Swamy NN, Nagaraj T, Ghouse N, Indians. J Oral Implantol 1994;20:118-23. Jagadish CD, Sreelakshmi N, Goswami RD. Radiographic study 17. Miller JA Jr. Studies on the location of the lingula, mandibular of mental foramen type and position in Bangalore population. foramen and mental foramen. Anat Rec 1953;115:349. 18. Matsuda Y. Location of the dental foramina in human skulls J Med Radiol Pathol Surg 2015;1:5-8.

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