How to assess the mandible (lower jaw) in conjunction with a sinus CT (computed tomography) scan?

Assessment of the Mandible in Conjunction with Sinus CT Scans

CT with multiplanar reconstructions is the optimal imaging modality for evaluating the mandible, with nearly 100% sensitivity for detecting mandibular fractures and abnormalities when compared to conventional radiography. 1

Imaging Technique and Advantages

CT imaging offers several significant advantages when assessing the mandible:

• Multiplanar reformations (MPR) and 3D reconstructions allow for comprehensive evaluation of the mandible's complex curved structure 1, 2
• Nearly 100% sensitivity for detecting mandibular fractures with improved interobserver agreement 1
• Superior visualization of posterior mandibular fractures, ramus, and condyle fractures where displacement can be subtle 1
• Critical for identifying comminution and displacement that may change surgical management 1
• Allows assessment of the mandible's relationship to adjacent structures in the maxillofacial region 3

Key Anatomical Areas to Assess on Mandibular CT

When evaluating the mandible on a sinus CT, pay particular attention to:

• Condylar region: Fractures here can cause deviation of the chin toward the fractured side during mouth opening and may be associated with blunt cerebrovascular injuries 4
• Mandibular canal: Assess for fractures that may damage the inferior alveolar nerve, potentially causing anesthesia of the ipsilateral lower lip, chin, anterior tongue, and mandibular teeth 1, 4
• Alveolar bone: Evaluate contour, height, thickness, and mineralization along the curvature of the jaw 2
• Mandibular body: Look for blunting at the inferior border, which is a strong predictor for the need for CT imaging in odontogenic infections 5
• Dental structures: Assess for periodontal lesions, periapical lesions, and condensing osteitis that may be visible on CT 6

Clinical Correlation with Imaging Findings

When interpreting mandibular findings on CT:

• Correlate with clinical signs such as altered dental occlusion, facial asymmetry, limitation of mandibular movements, and pain on palpation of the temporomandibular joint 4
• Note that mandibular fractures present in pairs in 67% of cases, so always verify there are no associated fractures 4
• Be aware that maxillary sinusitis may be odontogenic in origin in approximately 20% of cases 1
• Look for signs of nerve injury if fractures involve the mandibular canal 4

Technical Considerations

• Dental CT reformatting software can overcome many limitations of conventional axial and coronal CT by providing true cross-sectional and panoramic images 2, 7
• Streak artifacts from dental restorations often degrade CT images, but dental CT reformatting programs project these artifacts over the crowns of teeth, allowing better visualization of bone 7
• When evaluating for inflammatory disease, assess for periodontal lesions, periapical lesions, condensing osteitis, and maxillary sinus abnormalities associated with dental disease 6

Common Pitfalls to Avoid

• Failing to recognize that a complex fracture may be mistaken for an isolated fracture 1
• Missing nondisplaced or minimally displaced anterior fractures when there is overlap with the cervical spine 1
• Overlooking the association between mandibular fractures and cervical spine injuries, which occur in approximately 11% of patients with mandibular fractures 1
• Not considering that CT with IV contrast does not aid in detection of facial injury 1

By systematically evaluating these aspects of the mandible on sinus CT scans, clinicians can ensure comprehensive assessment and appropriate management of mandibular pathology.