Imaging Sci Dent.  2013 Dec;43(4):309-312. 10.5624/isd.2013.43.4.309.

Cone beam CT findings of retromolar canals: Report of cases and literature review

• Han SS
• Park CS

• KMID: 2229622
• DOI: http://doi.org/10.5624/isd.2013.43.4.309

Abstract

A retromolar canal is an anatomical variation in the mandible. As it includes the neurovascular bundle, local anesthetic insufficiency can occur, and an injury of the retromolar canal during dental surgery in the mandible may result in excessive bleeding, paresthesia, and traumatic neuroma. Using imaging analysis software, we evaluated the cone-beam computed tomography (CT) images of two Korean patients who presented with retromolar canals. Retromolar canals were detectable on the sagittal and cross-sectional images of cone-beam CT, but not on the panoramic radiographs of the patients. Therefore, the clinician should pay particular attention to the identification of retromolar canals by preoperative radiographic examination, and additional cone beam CT scanning would be recommended.

Keyword

Cone-Beam Computed Tomography; Mandibular Canal; Anatomic Variation

MeSH Terms

Anatomic Variation
Cone-Beam Computed Tomography*
Hemorrhage
Humans
Mandible
Neuroma
Paresthesia

Figure

• 

  Fig. 1 The sagittal (A) and cross-sectional images (B) clearly reveal a curving branch of the mandibular canal with a recurrent path at the right retromolar area (White arrow: retromolar canal, black arrow: main mandibular canal). C. The retromolar canal is not detectable on the routine panoramic radiograph.

• 

  Fig. 2 The retromolar canal branching from the right mandibular canal is identifiable in the sagittal (A) and cross-sectional images (B) (White arrow: retromolar canal, black arrow: main mandibular canal). C. The retromolar canal is not detectable on the routine panoramic radiograph.

Reference

1. Ossenberg NS. Retromolar foramen of the human mandible. Am J Phys Anthropol. 1987; 73:119–128.

2. Carter RB, Keen EN. The intramandibular course of the inferior alveolar nerve. J Anat. 1971; 108:433–440.

3. Bilecenoglu B, Tuncer N. Clinical and anatomical study of retromolar foramen and canal. J Oral Maxillofac Surg. 2006; 64:1493–1497.

4. Singh S. Aberrant buccal nerve encountered at third molar surgery. Oral Surg Oral Med Oral Pathol. 1981; 52:142.

5. Jablonski NG, Cheng CM, Cheng LC, Cheung HM. Unusual origins of the buccal and mylohyoid nerves. Oral Surg Oral Med Oral Pathol. 1985; 60:487–488.

6. Blanton PL, Jeske AH. ADA Council on Scientific Affairs, ADA Division of Science. The key to profound local anesthesia: neuroanatomy. J Am Dent Assoc. 2003; 134:753–760.

7. von Arx T, Hanni A, Sendi P, Buser D, Bornstein MM. Radiographic study of the mandibular retromolar canal: an anatomic structure with clinical importance. J Endod. 2011; 37:1630–1635.

8. Silva FM, Cortez AL, Moreira RW, Mazzonetto R. Complications of intraoral donor site for bone grafting prior to implant placement. Implant Dent. 2006; 15:420–426.

9. Langlais RP, Broadus R, Glass BJ. Bifid mandibular canals in panoramic radiographs. J Am Dent Assoc. 1985; 110:923–926.

10. Nortje CJ, Farman AG, Grotepass FW. Variations 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. 1977; 15:55–63.

11. Narayana K, Nayak UA, Ahmed WN, Bhat JG, Devaiah BA. The retromolar foramen and canal in south Indian dry mandibles. Eur J Anat. 2002; 6:141–146.

12. 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.

13. Naitoh M, Hiraiwa Y, Aimiya H, Ariji E. Observation of bifid mandibular canal using cone-beam computerized tomography. Int J Oral Maxillofac Implants. 2009; 24:155–159.

14. Kawai T, Asaumi R, Sato I, Kumazawa Y, Yosue T. Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study. Oral Radiol. 2012; 28:10–14.

15. Schejtman R, Devoto FC, Arias NH. The origin and distribution of the elements of the human mandibular retromolar canal. Arch Oral Biol. 1967; 12:1261–1268.

16. Sawyer DR, Kiely ML. Retromolar foramen: a mandibular variant important to dentistry. Ann Dent. 1991; 50:16–18.

17. Orhan K, Aksoy S, Bilecenoglu B, Sakul BU, Paksoy CS. Evaluation of bifid mandibular canals with cone-beam computed tomography in a Turkish adult population: a retrospective study. Surg Radiol Anat. 2011; 33:501–507.

18. Lizio G, Pelliccioni GA, Ghigi G, Fanelli A, Marchetti C. Radiographic assessment of the mandibular retromolar canal using cone-beam computed tomography. Acta Odontol Scand. 2013; 71:650–655.

19. Patil S, Matsuda Y, Nakajima K, Araki K, Okano T. Retromolar canals as observed on cone-beam computed tomography: their incidence, course, and characteristics. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013; 115:692–699.