The elusive retromolar foramen and retromolar canal: A CBCT study

This study aims to evaluate the presence of retromolar foramen (RMF) and retromolar canal (RMC) in the mandible using cone beam computed tomography (CBCT) in Chhattishgarh population and to correlate its possible clinical impact. 175 CBCT images were collected from which 100 bilateral CBCT images of patients were retrospectively selected from the Department of Oral Medicine and Radiology of the Chhattishgarh Dental College and Research Institute and evaluated bilaterally which were taken for diagnostic purposes from maxillofacial radiology clinic and data were statistically analyzed. This was an observational descriptive study and all the images were processed and analyzed on CS3D imaging software. The data was analyzed using chi square test. The prevalence of RMF and RMC was observed in 8.5%, of which 10 were in females and 7 in males. The RMCs traversed in different directions – horizontal, vertical and angular. Based on the subjective assessment, each of these canals was further subclassified into straight and curved canal. In the present study in 12 of the cases angular curved type was found and in 3 cases, vertical straight was noticed. The bifurcation of the inferior alveolar nerve (IAN) canal was observed in 15% of the scans and remaining 85% had single mandibular canal. The proximity of RMF from buccal and lingual cortical plates was found buccally in 16 cases and in single case was found to be lingually. Position of RMF might change with the presence and absence of third molar. The absence of third molar results in anteriorly located RMF. In majority of cases it was found that RMF was located more buccal than lingual. The parameters considered in the current study will guide the oral and maxillofacial surgeons while giving incisions in 3molar impacted cases, other pathologies and ease to preserve the retromolar foramen.

Conduction of Third Molar Extraction with the Presence of Retromolar Canal: A Case Report

Introduction: The retromolar canal is a structure rarely identified in clinical practice. The content of this canal is composed of nerves, arteries and venous plexus that give innervation and irrigation to the third molar region and the vestibular mucosa of molars and lower premolars. Thus, knowledge of the presence of this structure is important in dental procedures, due to the complications that damage to this structure can cause. Methods: In this report, a 19-year-old patient sought dental care at a clinic, Dentistry course at the Federal University of Santa Maria for the extraction of third molars due to hygiene difficulties. On radiographic examination, a retromolar canal was identified at the distal of the left mandibular third molar. With the identification of this structure, preventive measures were performed during the procedure to avoid complications. Results: With adequate planning and prevention measures, the trans and postoperative periods occurred without any complications. Conclusion: The foramen and the retromolar canal may occasionally appear in the clinic radiographic routine of the Dentist, and the professional should be attentive to the management of these anatomical structures during surgical procedures to avoid accidents and complications.

Evaluation of Retromolar Canals using Cone Beam Computer Tomography/ Avaliação do canal retromolar por meio de tomografia computadorizada de feixe cônico

The aim of this study was to evaluate the prevalence, location and clinical implications related to the presence of the retromolar canal (RMC) on cone beam computed tomography(CBCT). CBCT images of patients from Latin America Institute for Dental Research and Education - Curitiba,Pr,Brazil, was performed from June/2008 to February/2013. The interpretation was performed by a calibrated examiner, according to the criterias: presence, location and classification of the RMC variation, as well as, measurements of horizontal distances of the RMC in relation to the buccal bone cortical and diameter of these canals. A total of 751 CBCT images were interpreted: 486(64.7%) from females and 265 (35.3%) from male patients, with mean age of 54.57 (±13.23) years. The presence of RMC was observed in 58 (7.7%) patients, 23 men and 35 women. A total of 1502 hemi- mandibles were analyzed. The RMC was identified in 69(4.6%) hemi-mandibles, 44(63.8%) from females and 25(36.2%) from males. Thirty (42.8%) RMC were observed on the right side and 40 (57.2%) on the left one. The type B1 (n=33; 47.1%) was the most common, followed by the type A1 (n=18;25.7%). The mean diameter of RMC was 0.97mm (±0.44), and the mean distance between retromolar foramen and the buccal cortical of the mandible was 4.12mm (±1.35). There were no significant differences between the distances and genders, and distances and sides (p 0.05). The prevalence of RMC was 7.7% in the studied sample; they were predominantly unilateral and showed to be type B1.

Assessment of the Retromolar Canal in Taiwan Subpopulation: A Cross-Sectional Cone-Beam Computed Tomography Study in a Medical Center

The retromolar canal is an anatomical variation that occurs in the mandibular bone. The retromolar canal typically originates in the mandibular canal on the distal side of the third molar and extends forward and upward to the retromolar foramen (RMF), which contains the neurovascular bundle. Accidentally damaging the neurovascular bundle in the retromolar canal during the extraction of the third molar, dental implant surgery, or maxillofacial orthognathic surgery may lead to subsequent complications such as incomplete local anesthesia, paresthesia, and bleeding during operation. The objective of this study was to investigate the prevalence of the RMF in the Taiwanese population in a medical center by using dental cone-beam computed tomography (CBCT) and to identify the position of the RMF in the mandibular bone. The dental CBCT images for the mandibular bone of 68 hemi-mandible were uploaded to the medical imaging software Mimics 15.1 to determine the prevalence of the RMF in the Taiwanese population and the three positional parameters of the RMF in the mandibular bone: (1) The diameter of the RMF, (2) the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the second molar, and (3) the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal. Seven RMFs were observed in the 68 hemi-mandibles. Thus, the RMF prevalence was 10.3%. In addition, the diameter of the RMF was 1.41 ± 0.30 mm (mean ± standard deviation), the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the the second molar was 12.93 ± 2.87 mm, and the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal below second molar was 13.62 ± 1.3487 mm. This study determined the prevalence of the RMF in the Taiwanese population in a medical center and its relative position in the mandibular bone. This information can provide clinicians with a reference for posterior mandible anesthesia and surgery to ensure medical safety.

Incidence and Anatomical Properties of Retromolar Canal in an Iranian Population: A Cone-Beam Computed Tomography Study

Objectives. Retromolar canal (RC) is an anatomic structure, and due to increasing demand for surgical procedure in the retromolar area of the mandible, the identification of the retromolar canal has become an issue of clinical concern. It can innervate the third molar and some of the muscles around the posterior segment of the mandible, complicating surgical procedures in the retromolar area and root canal treatment of third molars. The aim of this study was to evaluate the incidence and anatomical properties of RC in a western Iranian population using cone-beam computed tomography (CBCT) images. Materials and Methods. Two hundred bilateral CBCT images were collected and screened in the three spatial planes for the presence of an RC. Anatomical properties and location of the RCs were assessed according to their course and distance from the surrounding structures. The relationship between the presence of RC and age, sex, side, and presence of second and third molars was also evaluated. Independent samples t-test, ANOVA, Tukey’s post hoc test, paired t-test, and chi-square were used to compare groups. Results. At least one RC was observed in 22% of the mandibles. Its bilateral incidence was 5.5%. Two major types of canals were detected, namely, type I, following a straight or curved course from the mandibular canal (MC) to the retromolar area (47.3%), and type II, coursing from the retromolar area to the radicular part of the third molar (52.7%). Regarding linear measurements, the mean RC diameter and the mean distance to the MC, second, and third molars were 0.68 ± 0.31, 13.7 ± 2.8, 15.3 ± 3.0, and 7.3 ± 2.3 mm, respectively. Conclusion. Based on the results of this study, RC was found in 22% of the cases; thus, it should be considered as a normal anatomical variation in the Iranian population rather than a rare finding.