Surgical and Radiologic Anatomy

, Volume 40, Issue 6, pp 647–652 | Cite as

The retromolar canals and foramina: radiographic observation and application to oral surgery

  • Shogo Kikuta
  • Joe Iwanaga
  • Ken Nakamura
  • Kiyosato Hino
  • Moriyoshi Nakamura
  • Jingo Kusukawa
Original Article



The retromolar canal (RMC) and foramen (RMF) are anatomic variants in the retromolar area of the mandible. The purpose of this study was to clarify the relationship between the RMC and RMF and related complications, and to reveal how the RMC could impact the mandibular anatomy using cone-beam computed tomography (CBCT) and panoramic images (PAN).

Materials and methods

CBCT and PAN images of 50 patients were retrospectively analyzed to investigate the morphology of the RMC and RMF, and their impact on impacted third molar surgery and orthognathic surgery.


In PAN images, neither the RMC nor RMF was detected. In CBCT images, the RMCs were detected in 26% (13/50) of the patients. A double RMC was detected on one side of one patient. The diameter of the RMC ranged from 0.8 to 2.9 mm (mean; 1.5 ± 0.6 mm), and the RMF ranged from 0.6 to 2.3 mm (mean; 1.1 ± 0.5 mm). No patients experienced unexpected bleeding. Unilateral postoperative hypoesthesia of the buccal gingiva in the molar region was reported in 6.7% of patients with the RMC.


Hypoesthesia of the buccal gingiva in the lower molar region may be the main complication when the RMC is damaged.


Cone-beam computed tomography Anatomic variation Mandible Oral surgery Retromolar canal Retromolar foramen 



The authors wish to express their gratitude to the radiological technician Reiji Katayama in the Diagnostic Imaging Center, Kurume University Hospital.

Author contributions

SK: protocol/project development, data collection or management, data analysis, and manuscript writing/editing, final approval/guarantor of manuscript. JI: protocol/project development, data analysis, manuscript writing/editing, and final approval/guarantor of manuscript. KN: data collection or management, data analysis, and final approval/guarantor of manuscript. KH: data collection or management, data analysis, and final approval/guarantor of manuscript. MN: protocol/project development, manuscript writing/editing, andfinal approval/guarantor of manuscript. JK: protocol/project development, data analysis, manuscript writing/editing, and final approval/guarantor of manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare no conflict of interest.


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Copyright information

© Springer-Verlag France SAS, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Dental and Oral Medical CenterKurume University School of MedicineKurumeJapan
  2. 2.Seattle Science FoundationSeattleUSA

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