CBCT Imaging Service - Frequently Asked Questions

Where do I go for my CBCT?
Upon arrival at the School of Dentistry you will check in at the Dental Faculty Associates (DFA) front desk. DFA is located in room 1340.
How long is my appointment going to take?
The actual CBCT scan takes approximately 20 seconds.  The total appointment time (including registration, positioning, scanning, reconstruction, and scan verification) is less than an hour. We ask that you arrive 30 minutes prior to your appointment to complete the patient registration process.
When should CBCT be used?
Whenever information in the 3rd dimension is needed for the diagnosis, treatment planning, or management of conditions in the jaws and the maxillofacial complex.
How much will my CBCT cost?
Please call the DFA office at 734-764-3155 for the current CBCT scan fee.
Will my insurance pay for my CBCT?
Most dental insurance companies do not cover CBCT scans. However, when the CBCT scan is ordered for medical purposes (i.e. trauma, pathology, sinus evaluation), some medical insurance companies may cover the scan fee. Our DFA staff would be happy to submit the claim to your insurance for reimbursement; however, payment is expected at the time of service.
What types of services are provided by the University of Michigan CBCT Imaging Service?
  • Prompt appointments through Dental Faculty Associates (DFA)
  • Written report by an Oral and Maxillofacial Radiologist, evaluating entire scan for pathology as well as for specific area of interest
  • PDF file of the Radiology report and images of interest are sent electronically
  • DICOM files of the scan or the scan plus the viewer software are transferred online or mailed on a CD
What are some typical uses of CBCT?
CBCT is used by general dentists and specialists to improve diagnosis and treatment planning in the following cases:
  • Dental implants
    • Location of anatomic structures: mandibular canal, submandibular fossa, incisive canal, maxillary sinus
    • Size and shape of ridge, quantity and quality of bone
    • Number, orientation of implants
    • Need for bone graft, sinus lift
    • Use of implant planning software
  • Oral and maxillofacial surgery
    • Relationship of third molar roots to mandibular canal
    • Localization of impacted teeth, foreign objects
    • Evaluation of facial fractures and asymmetry
    • Orthognathic surgery planning
  • Oral and maxillofacial pathology
    • Localization and characterization of lesions in the jaws
    • Effect of lesion on jaw in 3rd dimension: expansion, cortical erosion, bilateral symmetry
    • Relationship of lesion to teeth and other structures
  • Orthodontics
    • Treatment planning for complex cases when 3D information needed to supplement (or substitute for) other imaging
    • Patients with cleft palate
    • Impacted teeth
    • Root angulation, root resorption
  • Temporomandibular joint
    • Osseous structures of TMJ
    • Relationship of condyle and fossa in 3D
What are the advantages of CBCT?
  • Lower radiation dose than medical CT
    • Equivalent to ~1 Full mouth series of radiographs (FMX) or 6-7 panoramic radiographs
    • Thyroid shield can be used in many cases
  • Comfortable for patient
    • Open environment – no claustrophobia
    • Patient seated, facing out
    • Only 20 second scan
  • Wheelchair accessible
  • Images available almost immediately on screen
  • Images can be imported into other software
What is the radiation dose from a CBCT scan?
i-CAT FOV Effective dose (µSv) ICRP 1990 Effective dose (µSv) ICRP 2007
6 cm maxilla 9.7 36.5
6 cm mandible 23.9 75.3
8 cm both jaws 31.8* 100.4*
13 cm full head 39.5 110.5

*Estimated
JA Roberts et al. Effective dose from cone beam CT examinations in dentistry. BJR 82 2009):35-40.
An average person in the United States receives approx. 8 µSv/day of natural background radiation (3,000 µSv/year)

What are the main differences between a CBCT scan and a medical CT scan?
1.  Radiation dose:
Region scanned CBCT effective dose (µSv) ICRP 2007  Medical CT effective dose (µSv) ICRP 2007
Mandible 75.3 503*
Full head 110.5 1,088.3*

*Average from 3 scanners (Somaton VolumeZoom 4, Somatom Sensation 16, and Philips Mx8000 IDT)
M Loubele et al. Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. European Journal of Radiology 2009:71(3);461-8.

2.  Image resolution:  For hard tissues and teeth, CBCT offers higher resolution and image sharpness compared to medical CT (Multi-Slice CT or MSCT).
image resolution
M. Loubele et al. A comparison of jaw dimensional and quality assessments of bone characteristics with Cone-Beam CT, Spiral Tomography, and Multi-Slice Spiral CT. Int. J. Oral Maxillofac Implants 2007:22:446-454.

3.  Metal artifact reduction:  CBCT offers better metal artifact reduction compared to medical CT. This is important because many patients have metallic crowns or restorations that cause streaking artifacts that may interfere with the visualization of the region of interest.
metal artifact
C von See et al. Forensic imaging of projectiles using cone-beam computed tomography. Forensic Science International 190 2009:38-41.

4.  Soft tissue contrast:  One of the limitations of CBCT is the poor soft tissue contrast compared to medical CT or Magnetic Resonance Imaging (MRI). While CBCT is appropriate to evaluate osteoarthritic changes of the temporomandibular joint (TMJ), it is not suited for evaluation of TMJ disc displacement. Similarly, tumors within the soft tissue cannot be adequately evaluated using CBCT.