Cbct in Endodontics Diagnosis in Three Dimensions Radiography



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CBCT in Endodontics

Diagnosis in Three Dimensions
Radiography

  • 2 dimensional (2D) view

  • Shadow image

  • All structures superimposed

  • Must angulate multiple images to infer 3D information

  • High resolution images


2D Radiography

  • Foreign Objects

  • Buccal Object Rule

  • Vertical Angulation


Radiographs vs. CBCT

Advantages:



  • Three-dimensional view

  • Direct measurements possible

  • Can see osseous lesions better than radiographs

Disadvantages:

  • Poorer resolution than radiographs

  • Increased radiation dosage to patients

  • Increased cost

  • Learning curve

  • Liability of the reader

    • Send out to radiologist


3D Radiography

  • Fan Beam Computed Tomography

    • Medical Imaging

  • Cone Beam Computed Tomography

    • Medical and Dental Imaging

  • Micro-Computed Tomography

    • research only to date



Fan Beam vs Cone Beam
Voxel – 3 dimensional pixel (volume pixel)
Planes of View

  • Sagittal

  • Coronal

  • Axial


Field of View - The Volume that is Imaged

  • Large FOV

    • Medical

  • Medium FOV

    • Medical and Dental

    • iCAT

  • Small FOV

    • Dental

    • Kodak 9000 (CareStream)

    • Veraviewepocs 3D (J. Morita)


Endodontics = Small FOV


Small FOV

Advantages


Disadvantages



  • Difficult to image the entire jaw

  • Unsuitable for orthodontics or extensive implant case

  • Cannot make panoramic view


Resolution

  • Smaller voxel size = Higher resolution

  • Limited number of voxels that can be manipulated with commonly occurring computer processing power

  • Smaller FOV uses the same number of voxels as larger FOV but in a smaller space

  • Therefore smaller FOV = smaller voxels = greater resolution


Relative Effective Dosages
•Annual background radiation 3100 µSv

•4 BW (Digital or F-speed, Rectangular Collimation) 5 µSv

•FMX (Digital or F-speed, Rectangular Collimation) 35 µSv

•FMX (D-speed, Round Collimation) 388 µSv

•Panoramic (Digital 2 brands) 14-24 µSv

•Chest Radiograph 100 µSv

•Lower GI Tract Radiograph 8000 µSv

•CT Chest 7000 µSv

•CT (Maxillofacial Large FOV* 4 brands) 74-569 µSv

•CT (Maxillofacial Medium FOV* 8 brands) 69-860 µSv

•CT (Maxillofacial Small FOV* 5 brands) 23-488 µSv

•Airplane Round Trip to Florida 30 µSv

•Radon Gas (in our homes) 2000 µSv
Liability

“…the clinician can be liable for a missed diagnosis, even if it is outside his/her area of practice.” - AAE/AAOMR Position Statement


Should I take one on Every Patient?

“CBCT should only be used when the question for which imaging is required cannot be answered adequately by lower dose conventional dental radiography or alternate imaging modalities.” - AAE/AAOMR Position Statement


Software Interface
Clinical Outcomes

Assessment Criteria



  • Healed (Success)

  • Healing (Questionable)

  • Disease (Failure)


Healed (Success)

  • No PA Radiolucency

  • Asymptomatic

  • Clinical Signs WNL


Healing (Questionable)

OR

  • No Pa Radiolucency

  • Clinical Signs WNL

  • Mild Symptoms


Disease (Failure)

  • Overt Signs of Infection

    • Sinus Tract

    • Swelling

    • Increased Size of Radiolucency

  • Symptoms


Difficulty with Outcomes Assessments

  • Difficulty in setting up double blinded RCT’s

  • Large variation in pre-existing patient factors

  • Prevents randomization process

  • Blinding clinician difficult

  • Blinding patient may be unethical

Validity of Outcomes Studies in Question



  • Radiographic Assessment vs CBCT

  • Outcomes Criteria

    • Radiographic

      • Strindberg Criteria

      • Periapical Index (PAI)

    • CBCT

      • ???


Indications

  • Difficult Diagnosis

  • Treatment Planning

  • Resorption

    • Internal or External?

    • Extensive or Limited?

    • Prognosis?


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