Application of Cone Beam Computed Tomography Imaging to Dental and

Maxillofacial Practice.

ABSTRACT ID NO: IRIA-1162

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Radiographs for maxillofacial practice

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

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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.

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• 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

1. 2D to 3D approach to data acquisition and

2. Also provides opportunities for dental practitioners to request multiplanar imaging.

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• 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.

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Advantages and limitations of Cone Beam Computed Tomography

Advantages • X-ray beam limitation• Image accuracy• Rapid scan time• Dose reduction• Reduced image artefacts• Display modes unique to

maxillofacial imaging

Limitations• Currently- poor soft tissue

contrast.• Artifacts• Partial volume averaging• Under sampling• Image noise

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Cone Beam CT Technical Fundamentals

Image production can be done in• Sitting position• Standing position• Supine position

Components of CBCT image• Acquisition configuration• Image detection• Image reconstruction• Image display

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

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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.

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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.

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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.

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Post-operative assessment of maxillofacial trauma patient.

1. To check the fixation of

hard ware

2. To check for anatomic

reduction of fractured bone

fragments

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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.

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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.

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• 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.

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