Cone Beam Tomographic Imaging: Anatomy of the Maxillofacial Region

Overview and Purpose

Core Concept: Multiplanar Reformatting (MPR)

• CBCT acquires a volume of data that is stored and can be reformatted at any angle or plane
• This eliminates superimposition of adjacent structures
• The three standard planes are axial, coronal, and sagittal, plus cross-sectional (perpendicular to the dental arch)
• MPR has significantly increased diagnostic accuracy and efficiency for the knowledgeable clinician
• The same volume data can generate any view the diagnostician requires - a concept entirely new to most dentists

Anatomic Regions Reviewed in CBCT

1. Dental and Dentoalveolar Structures

• Cross-sectional images perpendicular to the arch-form of the maxilla or mandible are the starting point
• In the first molar region, buccal and palatal/lingual sides are clearly identified
• The maxillary sinus appears as a pyramidal, low-density (dark/black) structure because air attenuates X-rays minimally
• Healthy air-filled sinuses are dark; opacified sinuses indicate pathology

2. Nose and Paranasal Sinuses

• Maxillary sinuses (maxillary bone)
• Ethmoid air cells (ethmoid bone)
• Frontal sinuses (frontal bone)
• Sphenoid sinuses (sphenoid bone)

3. Axial Plane Anatomy

• Axial sections reveal the maxillary and mandibular dentition, lateral and medial sinus walls, lateral nasal cavity walls, zygomatic bones and arches, and the skull base
• At the floor of the mouth level: minimal soft tissue information is visible beyond cervical vertebrae and mandible
• At the maxillary sinus level: major sinus structures, nasal cavity, and nasopharynx are visible
• At the superior third of the sinuses: orbits, frontal sinuses, oral cavity, anterior sinus walls, and nasolacrimal ducts can be identified

4. Coronal Plane Anatomy

• At the premolar level: frontal sinuses, orbits, anterior maxillary sinuses, ethmoid air cells, and nasal cavity
• Reveals structures that are impossible to see in standard dental projections

5. Skull Base - Pterygopalatine Fossa (PPF)

• Located in contact with the posterior wall of both maxillary sinuses
• Two large osseous channels open into it:
  • Vidian canal (pterygoid canal) - carries fibers of the petrosal nerves
  • Foramen rotundum - carries the maxillary nerve (V2)
• The PPF connects the middle cranial fossa with:
  • Orbits (through the inferior orbital fissure)
  • Paranasal sinuses (through the sphenopalatine foramen)
  • Infratemporal fossa
  • Nasal cavity
• Clinical significance: Inflammation from orbits, nasal cavity, sinuses, and oral cavity can spread through this crossroad

Clinical Significance and Key Takeaways

1. Sectional imaging reveals spatial relationships that were "lost" in projectional 2D imaging
2. Dental professionals must understand that the same structure looks different in each plane - familiarity takes time and practice
3. CBCT allows viewing teeth and jaws from a third dimension that dentists have never seen before with traditional radiography
4. Incidental findings are common - paranasal sinus pathology, calcified carotid artery atheromas, cervical spine changes, and other non-dental structures appear in routine CBCT scans
5. A systematic approach to reading CBCT scans is essential to avoid missing pathology outside the primary area of interest

Related Literature

• Angelopoulos C. "Anatomy of the Maxillofacial Region in the Three Planes of Section." Dental Clinics of North America, 2014 - which further expanded coverage to include cervical spine, neck structures, and sphenoid sinus anatomy

1. Overview & Core Concept - What CBCT is and why MPR matters
2. The Three Imaging Planes - Comparison table (axial, coronal, sagittal, cross-sectional)
3. Axial Plane Anatomy - Level-by-level breakdown (floor of mouth → skull base)
4. Coronal Plane Anatomy - Anterior to posterior levels with key structures
5. Paranasal Sinuses - All 4 pairs with bone, shape, and clinical relevance
6. Pterygopalatine Fossa - Channels, contents, and 5 communication pathways
7. Cross-Sectional Imaging - Why it's unique and what it reveals
8. Incidental Findings - Region-by-region table of common non-dental findings
9. Key Terms Glossary - 14 defined terms
10. Self-Test Q&A - 8 review questions with full answers
11. Clinical Pearls - 10 high-yield takeaways