Mandibular retromolar foramen and canal - A systematic review and meta-analysis

Abstract

Introduction: The retromolar fossa is a small triangular area posterolateral to 3rd molar region in the mandible. The retromolar fossa often contains the retromolar foramen (RMF) as an anatomical variant. When the RMF is present, the foramen is connected with the mandibular canal (MC) through another canal known as the retromolar canal (RMC). RMC contains neurovascular bundle, which gives additional supply to the mandible. Although few studies have been conducted in past, a lacunae in comprehensive review is lacking. Although, these variations posed challenging situations for the practicing surgeons, they have been quite neglected and not well presented in textbooks. Hence, we made an attempt to provide a comprehensive and consolidated review regarding RMF and RMC. Materials and Methods: The relevant articles were selected by hand search and electronic media (Google scholar, PubMed, Science Direct, Medline, Embase and Cochrane) from 1987 to 2019. All the relevant articles were properly screened and findings were extracted from the articles. Results: There seems to be wide variations in morphology and morphometry of RMF and RMC. Discussion: Detailed knowledge of these anatomical variations is important in surgical procedure involving the retromolar area to protect the patient from complications such as unexpected bleeding, hematoma formation, and nerve damage. Furthermore, its knowledge makes us understand about the failed inferior alveolar nerve block, spread of infection, and metastasis in case of carcinoma. When there is any suspicious alteration in the MC, we suggest more accurate examination technique like CBCT.

Pulsatile hemorrhage posterior to the mandibular third molar due to abnormal branching of the inferior alveolar artery: A case report

“…RMC was classified into three types based on the CT findings (Figure 6) 3 : type A, vertical course; type B, curved course; and type C, horizontal course. The most common type of RMF is type A, which runs in the posterosuperior direction.…”

“…3 The branches of the inferior alveolar nerves (IAN) passing through the RMC provide additional supply to the surrounding mucosa and temporal and buccal muscles, and the branches of the inferior alveolar arteries anastomose with the branches of the buccal and facial arteries. 3 Although the presence of RMC and RMF is neglected in textbooks, it occasionally causes severe hemorrhage and nerve damage during surgery. [2][3][4][5] Herein, we report a case of pulsatile hemorrhage during extraction of a mandibular third molar and removal of a surrounding cyst-like lesion.…”

“…The inferior alveolar artery is divided into several branches; the branch at the mandibular angle chiefly supplies the region posterior to the molars or further branching to the molars, and branches in the mandibular body supply the teeth anterior to the point of branching 2 . Inferior alveolar artery branches passing through the retromolar canal (RMC) and retromolar foramen (RMF) may be present posterior to the mandibular third molar as an anatomical variation 3 . The branches of the inferior alveolar nerves (IAN) passing through the RMC provide additional supply to the surrounding mucosa and temporal and buccal muscles, and the branches of the inferior alveolar arteries anastomose with the branches of the buccal and facial arteries 3 .…”

Bifid Mandibular Canal: A Proportional Meta-Analysis of Computed Tomography Studies

“…In the review of Shah and Mehta [24], retromolar canal comprised 3.2% to 93.5% of dry mandibles. Tis range was fve times wider than ours.…”

“…One literature review stated that BMC ranged between 0.05% and 69% of the population [12]. In the review of Shah and Mehta [24], retromolar canal, one type of BMCs, revealed 3.2% to 93.5% of dry mandibles. Castro and fellows [25] contributed classifcations of BMCs.…”