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CASE REPORT Table of Contents   
Year : 2009  |  Volume : 20  |  Issue : 2  |  Page : 235-237
Bilateral bifid mandibular canal: Report of two cases


Department of Oral and Maxillofacial Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran

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Date of Submission06-Aug-2007
Date of Decision25-Oct-2007
Date of Acceptance04-Dec-2007
Date of Web Publication23-Jun-2009
 

   Abstract 

Bifid mandibular canal is a rare anatomical variation that can be of considerable interest to a dentist. This condition can lead to complications when performing mandibular anesthesia or during surgery of the lower third molar, orthognatic or reconstructive mandibular surgery, or placement of dental implants and prosthesis; bleeding and traumatic neuroma are possible complications. Therefore, awareness of this condition is important. We report two cases of bilateral bifid mandibular canal: one in a 22-year-old male and the other in a 24-year-old female.

Keywords: Anatomical variation, bifid mandibular canal, bilateral

How to cite this article:
Karamifar K, Shahidi S, Tondari A. Bilateral bifid mandibular canal: Report of two cases. Indian J Dent Res 2009;20:235-7

How to cite this URL:
Karamifar K, Shahidi S, Tondari A. Bilateral bifid mandibular canal: Report of two cases. Indian J Dent Res [serial online] 2009 [cited 2014 Sep 20];20:235-7. Available from: http://www.ijdr.in/text.asp?2009/20/2/235/52889
Some authors have used panoramic radiographs to study the prevalence of bifid mandibular canal. [1],[2],[3],[4],[5],[6],[7],[8] The incidence of this condition has been variably reported as 0.4%, [4] 0.08%, [9] and 0.9%. [6],[10]

A double mandibular canal can lead to complications while performing an inferior alveolar nerve block for obtaining mandibular anesthesia. [9],[11],[12],[13] The location and configuration of mandibular canal variations has important implications in surgical procedures involving the mandible such as dental implant treatment, sagittal split ramus osteotomy, and orthognatic and reconstructive surgeries; displacement of the third molar into the nerve canal during surgery, bleeding, and traumatic neuroma are some of its other complications. [3],[14],[15] In patients wearing prostheses this condition can cause pain and discomfort due to bone resorption [14] Using implants in these patients can also cause damage to the second canal. [3]

Bifid mandibular canals can be detected on a panoramic radiograph. [6],[7],[8] For more precise information about the accessory canals cross-sectional CT images, taken perpendicular to the alveolar ridge, can be used. [6],[14],[15],[16]


   Case Reports Top


Case 1

A 24-year-old female patient came to our dental school for a routine dental checkup. A panoramic radiograph revealed bilateral bifid mandibular canals. In the right jaw [Figure 1],[Figure 2],[Figure 3] the bifid mandibular canal was seen extending from the mandibular foramen toward two distinct mental foramina. In some locations, the canal walls were well corticated and three or four walls could be seen. In the left side of the jaw [Figure 1] and [Figure 4] the canals had three or four corticated walls and ended in a single mental foramen, which seemed bigger than usual. The patient had noticed that she had no third molar on both sides and had undergone an orthodontic procedure. As she had not undergone any procedure requiring anesthesia, she had not experienced any problems due to this condition.

Case 2

A 22-year-old male patient came to our dental school for a routine dental checkup. Panoramic radiograph showed bilateral bifid mandibular canals. In his right jaw [Figure 5] and [Figure 6] distinct canals could be seen with no walls in some areas and three or four well-corticated walls in other areas. In his left jaw [Figure 5] and [Figure 7] two separate canals with well-corticated walls could be seen. The patient mentioned that his dentist had had problems while administering local anesthesia during extraction of his left first molar.


   Discussion Top


Chavez et al. has suggested that during embryologic development the three inferior dental nerves innervating the three groups of mandibular teeth fuse together and form a single unified nerve in one canal. This theory would explain the existence of accessory canals resulting from lack of fusion of these canals. [17]

In 1973, Patterson, [1] using panoramic and lateral jaw radiographs, identified a case of unilateral bifid mandibular canal with two mental foramina. This seems to be the first such case to be reported, as no earlier reference to this condition has been found in the literature. [8] Similarly, in 1973, Kiersch and Jordan also reported one case [2] and noted that an osteocondensation image produced by the insertion of the mylohyoid muscle into the internal mandibular surface, with a distribution parallel to the dental canal, may mimic a bifid mandibular canal. [2],[8] The imprint of the mylohyoid nerve on the internal mandibular surface, where it separates from the inferior alveolar nerve and travels to the floor of the mouth, may also be a cause for confusion [8],[18],[19] A two-dimensional radiograph, such as a panoramic view, can not completely rule out the possibility of a deep mylohyoid groove on the medial aspect of mandibular surface, as the image on these two-dimensional representations can be confused with a second mandibular canal. [16] A number of other cases were reported in the subsequent years. [20] In 1978, an incidence of 0.9% was calculated, based on a study of 3612 panoramic radiographs. [10] Laglais et al. [6] observed 57 cases in 6000 routine panoramic radiographs (0.95%). Grover and Lorton [9] have reported a lower incidence (4 cases out of 5000 patients; 0.08%). Zografos [4] has found three cases in 700 panoramic radiographs (0.4%). Goodday et al. [21] have come across a double mandibular canal during orthognathic surgery. Thus, the incidence of bifid mandibular canal seems to be very low. [7],[8],[11],[12],[13],[14] Recently, there were two reports of bifid mandibular canals (6 cases in all) being diagnosed with the use of volumetric imaging (multislice helical computed tomography and cone-beam CT. [21],[22] Finally, it seems that for accurate observation of the location and configuration of the mandibular canals it is necessary to use cross-sectional images, taken perpendicular to the axis of the canals.

It is important for the dentist to be aware of the existence of a bifid mandibular canal so that he or she can choose a suitable technique for administering anesthesia (e.g., performing mandibular anesthesia at a higher level, the so-called 'Gow-Gates' technique). [6],[13] It was reported that inferior alveolar nerve passed through a single canal in 60% of cases, while in the other cases the canal was less defined and the nerves and vessels were spread out to occupy a space within the bone rather than a tunnel (as is seen in some locations in case 2 of the present series). [14] This can explain the absence of complete course of nerve canal. [22] As different branches of inferior alveolar nerve supply different teeth groups, congenital absence of some teeth (as seen in case 1) can be attributed to lack of development of some branches of the nerve. [22]

 
   References Top

1.Patterson JE, Funke FW. Bifid inferior alveolar canal. Oral Surg Oral Med Oral Pathol 1973;36:287-8.  Back to cited text no. 1    
2.Kiersch TA, Jordan JE. Duplication of the mandibular canal. Oral Surg Oral Med Oral Pathol 1973;35:133-4.  Back to cited text no. 2    
3.Quattrone G, Furlini E, Bianciotto M. [Bilateral bifid mandibular canal: Presentation of a case]. Minerva Stomatol 1989;38:1183-5.  Back to cited text no. 3    
4.Zografos J, Kolokoudias M, Papadakis E. The types of mandibular canal. Hell Period Stomat Gnathopathoprosopike Cheir 1990;5:17-20.  Back to cited text no. 4    
5.Driscoll CF. Bifid mandibular canal. Oral Surg Oral Med Oral Pathol 1990;70:807.  Back to cited text no. 5    
6.Langlais RP, Broadus R, Glass BJ. Bifid mandibular canals in panoramic radiographs. J Am Dent Assoc 1985;110:923-6.  Back to cited text no. 6    
7.Wyatt WM. Accessory mandibular canal: Literature review and presentation of an additional variant. Quintessence Int 1996;27:111-3.  Back to cited text no. 7    
8.Sanchis JM, Penarrocha M, Soler F. Bifid mandibular canal. J Oral Maxillofac Surg 2003;61:422-4.  Back to cited text no. 8    
9.Grover PS, Lorton L. Bifid mandibular nerve as a possible cause of inadequate anesthesia in the mandible. J Oral Maxillofac Surg 1983;41:177-9.  Back to cited text no. 9    
10.Nortje CJ, Farman AG, Grotepass FW. Variation in the normal anatomy of the inferior dental (mandibular) canal: A retrospective study of panoramic radiographs from 3612 routine dental patients. Br J Oral Surg 1978;15:55.  Back to cited text no. 10    
11.Desantis L, Liebow C. Four common mandibular nerve anomalies that lead to local anesthesia failures. J Am Dent Assoc 1996;127:1081-6.  Back to cited text no. 11    
12.Wong MK, Jacobsen PL. Reasons for local anesthesia failures. J Am Dent Assoc 1992;123:69-73.  Back to cited text no. 12    
13.Meechan JG. How to overcome failed local anesthesia. Br Dent J 1999;186:15-20.  Back to cited text no. 13    
14.Claeys V, Wackens G. Bifid mandibular canal: Literature review and case report. Dentomaxillofac Radiol 2005;34:55-8.  Back to cited text no. 14    
15.Naitoh M, Hiraiwa Y, Aimiya H, Gotoh M, Ariji Y, Izumi M, et al. Bifid mandibular canal in Japanese. Implant Dent 2007;16:24-32.  Back to cited text no. 15    
16.Rouas P, Nancy J, Bar D. Identification of mandibular canals: Literature review and three case reports with CT scans and cone beam CT. Dentomaxillofac Radiol 2007;36:34-8.  Back to cited text no. 16    
17.Chαvez-Lomeli ME, Mansilla Lory J, Pompa JA, Kjaer I. The human mandibular canal arises from three separate canals innervating different tooth groups. J Dent Res 1996;75:1540-4.  Back to cited text no. 17    
18.Wilson S, Johns P, Fuller PM. The inferior alveolar and mylohyoid nerves: An anatomic study and relationship to local anesthesia of the anterior mandibular teeth. J Am Dent Assoc 1984;108:350-2.  Back to cited text no. 18    
19.Sillampaa M, Vuori V, Lehtinen R. The mylohyoid nerve and mandibular anesthesia. Int J Oral Maxillofac Surg 1988;17:206-7.  Back to cited text no. 19    
20.Byers SS, Ratcliff JS. Bifurcated mandibular canal. Oral Surg Oral Med Oral Pathol 1983;56:337.  Back to cited text no. 20    
21.Goodday RH, Com B, Precious DS. Duplication of mental nerve in a patient with cleft lip-palate and rubella syndrome. Oral Surg Oral Med Oral Pathol 1988;65:157-60.  Back to cited text no. 21    
22.Auluck A, Ahsan A, Pai KM, Shetty C. Anatomical variations in developing mandibular nerve canal: A report of three cases. Neuroanatomy 2005;4:28-30.  Back to cited text no. 22    

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Correspondence Address:
Kasra Karamifar
Department of Oral and Maxillofacial Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz
Iran
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DOI: 10.4103/0970-9290.52889

PMID: 19553729

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]

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