The unusually lower position of the mandibular foramen and the canal of the neck of mandible.

BACKGROUND: The inferior alveolar nerve (IAN) courses through the mandibular foramen (MF) to enter the first segment of the mandibular canal (MC) in the mandibular ramus, to further supply with trigeminal fibers the lower teeth of that hemimandible. As the IAN also supplies the mylohyoid nerve, it is a mixed nerve. METHODS: Unusual morphologies of the mandibular ramus were encountered during a retrospective study of archived CBCT files. RESULTS: A previously unreported anatomic variation was found bilaterally in an edentulous mandible, consisting of a lowered position of the MF, with seemingly compensatory lengthening and enlargement of the sulcus colli, thus shortened MCs. Also, a rare neurovascular canal of the neck of the mandible was incidentally found unilaterally in another case and is reported here. CONCLUSIONS: Such possibilities of variation could justify the individual effect of the IAN block.

Air spaces neighbouring the infraorbital canal.

OBJECTIVE: The infraorbital canal (IOC) courses through the roof of the maxillary sinus (MS). Different grading systems concerning the topography of the IOC have been proposed. Further, it has been suggested that a transantral IOC would be morphologically related to Haller's cells (HCs). However, we hypothesized that this is not necessarily the case. Hence, we aimed to study the anatomical possibilities of the air spaces located medially to the IOC. MATERIALS AND METHODS: The cone-beam computed tomography (CBCT) files of 40 adult patients were retrospectively evaluated. RESULTS: The transantral type of IOC was found in 32.5% of patients. The infraorbital recesses of the MS were found medial to the IOC in 20% of patients. As referred to the nasolacrimal canal, these recesses were either prelacrimal (appearing as false isolated air cells) or retrolacrimal (appearing as false HCs). True HCs were found in 10% of patients. They were located medial to the IOC and they drained into the ethmoidal infundibulum (EI), which was distinct from the MS drainage. In 15% of patients, aerated nasolacrimal ducts (NLDs) were found anterior to the EI and medial to the antral angle. They were capable of masquerading either a HC or an infraorbital recess of the MS. CONCLUSION: Previous classifications of the IOC, which related it to HCs, were reviewed and the evidence was found to be insufficient to assess the HC-related topography of the IOC. Therefore, to achieve the accurate anatomical identification of the air spaces neighbouring the IOC, the infraorbital recesses of the MS, the HCs, and the aerated NLDs should be carefully discriminated within the antero-supero-medial antral angle.

Three-dimensional anatomy of the transantral intraseptal infraorbital canal with the use of cone-beam computed tomography.

The transantral or ectopic infraorbital canal (IOC) courses diagonally through the maxillary sinus (MS), thereby being exposed to risk during a number of surgical procedures. A few prior reports have presented evidence of a septa-embedded IOC, albeit only on single-plane slices. We identified this extremely rare variation of the IOC during a retrospective study of the cone-beam computed tomography files of 2 patients. In the first case, which involved a 34-year-old female patient, the canals and septa within the MS were bilaterally asymmetrical. On the right side, the sinus roof was attached to a short transverse septum that was traversed by the IOC, while the left sinus featured an oblique large septum that divided it into antero-superior and posterior chambers. The left IOC was embedded within the septum rather than within the orbital floor above the septum. In the second case, which concerned a 36-year-old male patient, the left MS featured an almost completely oblique/vertical septum that divided it into anterior and posterior chambers and also embedded the respective IOC, which was thus absent from the orbital floor. In both cases, infraorbital recesses in the anterior chambers of the MS were found that, if not documented on three-dimensional (3D) renderisations, could have been misidentified as infraorbital (Haller) cells. To the best of our knowledge, this is the first report to document the 3D anatomy of an extremely rare variant, namely a septum-embedded transantral IOC. Such a variant, if not adequately documented preoperatively, could divert the transmaxillary corridors down false paths or else expose the IOC to damage during surgical procedures involving access to tumours.