Application of Cone Beam Computed Tomography Imaging to Dental and Maxillofacial Practice. ABSTRACT ID NO: IRIA-1162

Radiographs for maxillofacial practice Images of maxillofacial skeleton demonstrating 2 Dimensional view, haziness, overlapping, artefacts, distortion etc.

Introduction Imaging is an important diagnostic adjunct to the clinical assessment of the dental patient and guidelines for the selection of appropriate radiographic procedures for patients suspected of having dental and maxillofacial diseases are available. Although combination of plain X-ray transmission projections and panoramic radiography can be adequate in a number of clinical situations, radiographic assessment may sometimes be facilitated by multiplanar images including computed tomographs.

For most dental practitioners, the use of advanced imaging has been limited because of cost, Availability and radiation dose considerations. However, the introduction of Cone Beam Computed Tomography [CBCT] specifically dedicated to imaging the maxillofacial region heralds a true paradigm shift from 2D to 3D approach to data acquisition and Also provides opportunities for dental practitioners to request multiplanar imaging.

Dental practitioners are familiar with the thin-size images produced in the axial plane by conventional helical fan-beam CT. CBCT allows the creation in ‘Real Time’ of images not only in the axial plane but also 2-dimensional images in the coronal, sagittal and even oblique or curved image planes- a process referred to as multiplanar reformation[MPR]. In addition, CBCT data are amenable to reformation in a volume, rather than a slice providing 3- dimensional information and expanding the role of imaging from diagnosis to image guidance of operative and surgical procedures by way of applications software.

Advantages and limitations of Cone Beam Computed Tomography X-ray beam limitation Image accuracy Rapid scan time Dose reduction Reduced image artefacts Display modes unique to maxillofacial imaging Currently- poor soft tissue contrast. Artifacts Partial volume averaging Under sampling Image noise

Cone Beam CT Technical Fundamentals Image production can be done in Components of CBCT image Sitting position Standing position Supine position Acquisition configuration Image detection Image reconstruction Image display

X-ray beam projection scheme comparing acquisition geometry of conventional or fan beam geometry and cone beam imaging geometry.

An overview of the unique image display capabilities of maxillofacial CBCT systems and to illustrate specific applications in dental and maxillofacial practice. Root calcification Odontogenic cyst of the maxilla Root fracture Mandibular jaw fracture Canine tooth impaction Condylar neck of the mandibular bone fracture. Post-operative assessment of maxillofacial trauma patient. Virtual implant placement.

Pre-surgical anatomic assessment of mandibular fracture. FOV: 200mm x 100mm Panoramic image demonstrating a well defined radiolucent line present on right body of mandible extending interdentally between 43,44 extending downwards, backwards to lower border of mandible suggesting a fracture. Coronal, sagittal and axial section showing the fracture involvement of buccal and lingual cortical plates and its close proximity to mental foramen. CBCT imaging of maxillofacial region provides opportunities for 3 D viewing and Multiplanar imaging.

Pre-surgical assessment of canine impaction 3D Panoramic view showing bilateral canine impaction. The sagittal view shows the direction of the tooth. i e the root more close to the lingual cortex The coronal section showing the approximity of the impacted canine tooth to the adjacent tooth structures.

Post-operative assessment of maxillofacial trauma patient. To check the fixation of hard ware 2. To check for anatomic reduction of fractured bone fragments

Use of CBCT in virtual implant placement for a lower molar tooth. CBCT scan can assess bone height, bone profile, associated anatomy and to aid the implant placement in the correct angulation. CBCT with virtual implant, healing abutment and crown showing the ideal final result. The measurement from the apex of the virtual implant to the mandibular canal is 1.81mm. 3 Dimensional view of the virtual implant.

Discussion Diagnostic information directly influences clinical decisions. Accurate data lead to better treatment-planning decisions and potentially more predictable outcomes. CBCT is an emerging technology that can offer the clinician clinically relevant information that cannot be gathered from conventional radiography. The ability to assess an area of interest in 3 dimensions eliminates the superimposition that is inherent in conventional radiographic imaging.

The cases outlined in this paper exemplified clinical situations that might benefit from further imaging information to provide the best clinical care. The patient’s history and clinical examination must justify the use of CBCT by demonstrating that the benefits to the patient outweigh the potential risks. However, it should be prescribed only after weighing the cost of radiation exposure with the benefit of the diagnostic information that can be obtained from the scan.