Objective The study aims at assessing the incidence, course, and characteristics of retromolar canals. Study design The cone-beam computed tomography images of 171 subjects were evaluated for the presence, course, and pattern of occurrence of retromolar canals. Results Three types of retromolar canals namely A, B, & C were detected in 129 subjects. Type A branched off the mandibular canal distal to third molar to open into retomolar fossa, type B coursed between retromolar fossa and radicular portion of third molar, type C coursed from mandibular foramen anteroinferiorly to exit into retromolar fossa. The type B retromolar canal presented features distinguishing it from other types. Conclusions Considerable number of individuals presented with retromolar canals emphasizing their significance in surgeries involving the retromolar area. The type B pattern, to the best of our knowledge, hasn't been reported by most researchers and hence, could be considered as an additional type of retromolar canal.

Retromolar canals as observed on cone-beam computed tomography: their incidence, course, and characteristics

Objectives:To investigate the anatomical variations of the mandibular canal through assessment in situ, panoramic radiography, CT or CBCT and assess their frequency.Methods:Articles were selected from databases (Cochrane Library, LILACS, ProQuest, PubMed, Scopus, Web of Science and Google Scholar), articles without limitations of language, in which the main objective was to evaluate the frequency of bifurcation of the mandibular canal through assessment in situ, panoramic radiography, CT or CBCT were selected. A meta-analysis of prevalence using random effects was performed.Results:Using a selection process in two phases, 15 articles were identified, and a meta-analysis was conducted. The results from these meta-analyses showed that the overall prevalence of anatomical variations for in situ studies was 6.46%, and through assessment of panoramic radiography and CT or CBCT the overall prevalence shown was 4.20% and 16.25%, respectively.Conclusions:There are two types of variations of the mandibular canal: ...

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Anatomical variations of mandibular canal detected by panoramic radiography and CT: a systematic review and meta-analysis

Objectives:To examine the presence and morphologic characteristics of bifid mandibular canals (BMCs) and retromolar foramens (RFs) using cone beam CT (CBCT) and to determine their visualization on panoramic radiographs (PANs).Methods:A sample of 225 CBCT examinations was analysed for the presence of BMCs, as well as length, height, diameter and angle. The diameter of the RF was also determined. Subsequently, corresponding PANs were analysed to determine whether the BMCs and RFs were visible or not.Results:The BMCs were observed on CBCT in 83 out of the 225 patients (36.8%). With respect to gender, statistically significant differences were found in the number of BMCs. There were also significant differences in anatomical characteristics of the types of BMCs. Only 37.8% of the BMCs and 32.5% of the RFs identified on CBCT were also visible on PANs. The diameter had a significant effect on the capability of PANs to visualize BMCs and RFs (B = 0.791, p = 0.035; B = 1.900, p = 0.017, respectively).Conclusions:...

Descriptive study of the bifid mandibular canals and retromolar foramina: cone beam CT vs panoramic radiography.

Anthropomorphic assessment of the retromolar foramen and retromolar nerve: anomaly or variation of normal anatomy?

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). 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.

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

The retromolar foramen (RMF) is an anatomical structure on the alveolar surface of the retromolar area. This foramen runs consecutive to the retromolar canal (RMC), which diverges from the mandibular canal. It is important to confirm the RMF and canal locations prior to surgical procedures, such as extraction of an impacted molar and bone harvesting as a donor site for bone graft surgery. This aim of this study was to investigate the RMF in Japanese cadaver mandibles using cone-beam computed tomography (CBCT) images and anatomical observations. Ninety sides of 46 cadaver mandibles were investigated in this study. CBCT images around the retromolar region were acquired for all of the mandibles. The frequency and anteroposterior and buccolingual locations of the RMF were examined on these images. Subsequently, four sides of three mandibles were dissected to confirm the contents of the RMC/RMF. In 24 of 46 (52%) mandibles and 34 of 90 (37%) sides, at least one RMF was observed in the images. In 26 dentate mandibles, 12 (48%) mandibles and 14 (33%) sides presented at least one RMF. The average location of the RMF was 14.4 mm posterior from the distal edge of the second molar. The buccolingual location was 3.0 mm lingual from the mandibular canal. Observations made during the cadaver dissections confirmed that the vessels and nerves diverged from the mandibular canal. The findings suggest that the RMF is not a rare anatomical structure and that practitioners should take this foramen into account in all anesthetic and surgical procedures involving the retromolar area.

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

The mandibular ramus is regarded as a relatively safe zone for a sagittal splitting osteotomy or for harvesting bone during implant treatment. The only important anatomical structure is the mandibular canal. The mandible has some anatomical variants that need to be recognized, such as a bifid mandibular canal, a retromolar canal, and rarely a temporal crest canal (TCC). In this study, cadaver mandibles were used to evaluate the TCC in the mandibular ramus using cone beam computed tomography (CBCT). Altogether, 90 sites on 48 mandibles from Japanese cadavers were examined in this study. The CBCT volumetric images were acquired for areas of 79 mm
 $$\varphi \times $$
 71 mm. Three-dimensional observation of the images was undertaken to estimate the frequency, position of the orifices, and canal continuity. The cadaver mandibles in which the TCCs were observed were dissected from the inner surface to confirm the contents. Five TCCs (5.6 %) were observed in 90 observation areas. At least one TCC was confirmed in four (8.3 %) of 48 mandibles. Two types of TCC were recognized. Dissection revealed that they contained neurovascular bundles. Three-dimensional diagnosis is essential prior to surgical procedures in the mandibular ramus because unexpected blood vessels may be present that may cause bleeding or complications during the surgery.

Observation of the temporal crest canal in the mandibular ramus by cone beam computed tomography and macroscopic study

This paper reports the four cases of the condylar head fractures of the mandible The diagnostic images with panoramic radiograph and CT are presented From 4 cases of condylar head fractures, the incidence, causes, and mechanisms are also discussed together with previous report

Image-based diagnosis of condylar head fractures of the mandible: four case studies

Calcifying lesions in the jaws are usually solitary and can be diagnosed by intraoral, panoramic, and conventional extraoral radiographs. It is extremely rare for these calcifying lesions to be multiple, unless they are associated with certain systematic diseases. Herein, we report a rare case of multiple odontomas in a 4-year-old girl. The lesions were scattered throughout both jaws on the panoramic image. The reconstructed CT image showed lesions in the left maxilla that occupied the sinus and affected the floor of the left orbit. The lesions in the mandible were widespread and extended to the tooth-bearing area. Enucleations of the maxillary parts were performed, and the pathological diagnosis was a mixture of complex and compound odontomas. The 3-year postoperative follow-up by panoramic imaging was uneventful. Preoperative CT was useful for the differential diagnosis by depicting the internal calcifying lesions and revealing the extent and complex relationships among the lesions.

Multiple calcifying lesions in the maxilla and mandible of a 4-year-old girl: report of a rare case and literature review

A 44-year-old woman visited a general practitioner with a chief complaint of painless swelling on her palate that interfered with the functional movement of her tongue. She was referred to our university hospital. There was nothing noteworthy in her family or personal medical history. Although she had become aware of the swelling a few years earlier, she had let it go untreated because it was painless. Macroscopically, several areas of swelling were observed on the palatine and palatal surface of the alveolar bone bilaterally; these areas, which altogether occupied half of her oral cavity, were independent from each other, as they were separated by a mucosal layer. The mucosa on the surface of the swelling looked healthy, but a portion on the left side was white. Upon palpation, a bony hardness was felt. Clinically, the swelling was diagnosed as tori palatinus (Fig. 1). Postero-anterior and lateral skull radiographs showed an oval-shaped, radiopaque mass hanging from the patient’s hard palate. The images were superimposed onto the maxillary teeth and alveolar process (Fig. 2a,b). A computed tomography (CT) examination was performed to get more detailed information about the swelling, and to distinguish it from other hard tissue diseases such as osteosarcoma or fibrous dysplasia. Multiplanar reconstruc-

Yasuo Kumazawa

Papers

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

Observation of the temporal crest canal in the mandibular ramus by cone beam computed tomography and macroscopic study

Image-based diagnosis of condylar head fractures of the mandible: four case studies

Multiple calcifying lesions in the maxilla and mandible of a 4-year-old girl: report of a rare case and literature review

A case of exceptionally large tori palatinus