Although CBCT is a great tool that provides 3D images, it does not replace standard dental radiographic images and should be utilized as a complementary tool for specific cases, and not for routine cases. CBCT studies with small field of view and small voxel size will provide improved spatial resolution, especially for endodontic purposes.
The advantages of CBCT over panoramic radiographs are 3D analysis, no superimposition or distortion, and the ability to create cross-sectional images. The disadvantages over panoramic imaging are increased radiation dose, acquisition artifacts, and cost.
The advantages of the CBCT over MDCT are faster scan time with less potential for movement artifact, less cost, and less radiation exposure to the patient. A major disadvantage is poor soft tissue contrast, which prevents soft tissue assessment.
National Council on Radiation Protection and Measurements (NCRP) has recently published Report No.177 in 2019 - Radiation Protection in Dentistry and Oral & Maxillofacial Imaging. Because CBCT units are markedly more sophisticated than any of the other dental imaging devices, appropriate education and proper training for practitioners and operators are critical in the safe and effective use of this modality. On its recommendation 62, it says “Every person who operates cone-beam computed tomography (CBCT) equipment, supervises the use of CBCT equipment, or tests and evaluates the functions of CBCT equipment shall have ongoing continuing education in the safe and effective use of that equipment.”
There are several steps the clinician must check and analyze for each patient and clinical situation:
Region of interest and field of view: Which teeth or anatomical structures are to be visualized? Are the TMJ areas to be included in the scan? Is visualization of both dental arches required, or only one arch? Is partial visualization of the maxillary sinuses enough?
Radiographic Guide: Is a radiographic marker showing the exact location of the desired implant site indicated? Will guided surgery be required? Is the radiographic guide well-adapted? In cases where the scan will be acquired at a separate location and a radiographic guide will be used, the referring clinician must pre-fit and assess the guide prior to the scan appointment. Also, the clinician should explain to the patient the correct position of the radiographic guide to avoid malposition.
Voxel size: Which voxel size would be the best for this specific situation?
Other: Should the patient’s teeth be in maximum intercuspal occlusion while acquiring the scan or with teeth apart? Should cotton rolls be placed between teeth to separate the arches or should a bite registration be used?
If an oral and maxillofacial radiologist is to write a report on the scan, it is important to provide enough clinical information (age, gender, significant past medical history, duration of the pain or swelling) to assist in formulating an accurate differential diagnosis and treatment options.
It is the dentist’s responsibility to critically assess the need for a CBCT study on a case-by-case basis, and to provide an interpretation of the entire data volume. This applies whether the clinician ordered or acquired the CBCT scan, and whether for use within that dental clinic or for use by a referral client.