IJCRR - 4(5), March, 2012
Pages: 108-110
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BILATERAL ACCESSORY MENTAL FORAMEN- A CASE REPORT
Author: Raju Sugavasi, Sujatha.M, Indira Devi.B, Sirisha.B
Category: Healthcare
Abstract:Accessory mental foramen of the mandible is not a common anatomical variation. Presence of
any such variation during implant placement, regional anesthesia and surgical correction of the
jaw deformities may develop neurovascular complications. In order to avoid complications, the
probability of the existence of an accessory mental foramen should be kept in mind. During
routine osteology demonstration classes we noticed an accessory mental foramen on both sides
of mandible. So particular attention should be paid to the possible occurrence of one or more
accessory mental foramen during surgical procedures involving the mandible. The clinical
implications of such variation are discussed in this paper.
Keywords: Mandible, mental foramen, anesthesia, accessory mental foramen.
Full Text:
INTRODUCTION
The anatomical position of the mental foramen usually lies midway between the upper and lower boarders of the body of the mandible, either below the first pre molar teeth or the second. The mental neurovascular bundle emerges from the mental foramen. The posterior boarder of the foramen is smooth and accommodates the nerve as it emerges posterolaterally[1] . The inferior alveolar nerve divides into mental and incisive branches near the mental foramen. The mental nerve leaves the mandible via the mental foramen whereas the incisive nerve remains within the bone and supplies the anterior teeth. The mental nerve may extend anteriorly for 2–3 mm within the mandible before curving back to the mental foramen, called the anterior loop of the mental nerve. The intra osseous course of the mental nerve is of particular importance in dental implant surgery. The nerve may be damaged if the inter foraminal area of the mandible is invaded during surgery or while harvesting block grafts from the symphysial region. The mental foramen is most usually single in humans, when it is double or multiple the additional foramens are termed as accessory mental foramen.
Case report:
During routine osteology demonstration classes for the undergraduate students, we observed an accessory mental foramen bi laterally in an adult mandible, as shown in figure-01 .The accessory mental foramen is located anterolateral aspect of body of mandible just anteroinferior to the normal mental foramen, between the canine and premolar tooth, mid way between upper and lower borders of body. As measured by the measuring tape it is about 12-14 mm superior to the inferior border.
DISCUSSION
According to previous studies by different authors, the incidence of accessory mental foramen is as follows. Sawyer DR et al (1998)[2] reported the incidence of accessory mental foramen as 2.6% in French, 1.4% in American Whites, 5.7% in American Blacks, 3.3% in Greeks, 1.5% in Russians, 3.0% in Hungarians, 9.7% in Melanesians, and 3.6% in Egyptians. According to Toh H et al (1992) [3] accessory mental foramen is less rare, with a prevalence ranging from 6.7 to 12.5% in Japan in a Japanese population. Absence of mental foramen has also been reported, According to De Freitas et al (1979) [4] mental foramen was absent in 3 cases out of 2870 sides of 1435 dry skulls. Cagirankaya LB et al (2008) [5] reported that accessory mental foramen is rare, with a prevalence ranging from 1.4 to 10 %. According to Naitoh M (2009) [6] theory, the mental foramen is incomplete until the 12th gestational week, when the mental nerve separates into several fasciculi at that site. It has been suggested that separation of the mental nerve earlier than the formation of the mental foramen could be a reason for the formation of the accessory mental foramen. Accessory foramen of the mandible is common. They may transmit auxiliary nerves to the teeth from facial, buccal, transverse cervical cutaneous and other nerves[7] .
CONCLUSION
This article reviews the clinical importance of accessory mental foramen. The Accessory mental foramen and their occurrence are clinically significant in dental anesthetic blocking techniques, surgical correction of jaw deformities and periapical surgeries. Care should be taken to the accessory mental foramen and nerve during dental implant surgery and in any surgical procedure involving the mandibular molar and premolar region, so that the rate of paralysis and hemorrhage in mental region can be reduced. In harvesting the block grafts from symphysial region, the nerve may be damaged, so the intra osseous course of the mental nerve is of particular importance.
ACKNOWLEDGEMENTS
To begin with, I express my deep sense of gratitude to Dr. Kanchana latha professor and HOD of Anatomy, Dr. Uday Kumar and my colleagues for their proper guidance, precious suggestions and priceless encouragements to accomplish my work. I am very much greatful to the research scholars and so many authors whose efforts have helped me to update my knowledge of Anatomy and stirred up my zeal to continue the work. I am immensely indebted to IJCRR (international journal of current research and review) editors and publishers for the opportunity given to me to contribute to the subject of anatomy.
References:
1. Standring S. Gray?s Anatomy. The Anatomical basis of clinical practice. 40th ed. Edinburg. Elsevier Churchill Livingstone. 2008; 31: p.530.
2. Sawyer DR, Kiely ML, Pyle MA. The frequency of accessory mental foramina in four ethnic groups. Archives of Oral Biology. 1998; 43(5): 417 - 420.
3. Toh H, Kodama J, Yanagisako M, Ohmori T. Anatomical study of the accessory mental foramen and the distribution of its nerve. Okajimas Folia Anat Jpn. 1992; 69: 85 - 87.
4. de Freitas V, Madeira MC, Toledo Filho JL, Chagas CF. Absence of the mental foramen in dry human mandibles. Acta Anat(Basel). 1979; 104(3): 353-355.
5. Cagirankaya LB, Kansu H. An accessory mental foramen. A case report. J Contemp Dent Pract. 2008; 9(1): 98 - 104.
6. Naitoh M, Hiraiwa Y, Aimiya H, Gotoh K, Ariji E. Accessory mental foramen assessment using cone-beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009; 107(2): 289 - 294.
7. Standring S. Grays Anatomy. The Anatomical basis of clinical practice. 40Th ed. Edinburg. Elsevier Churchill Livingstone. 2008; 31: p.532.
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