Imaging of the dentofacial structures is an important diagnostic tool as part of comprehensive orthodontic treatment. In 1931, Broadbent was the pioneer in evaluating the dentofacial structures in three dimensions (3D), namely in using two images taken in the sagittal (left to right) and (back to front) frontal views. Since then, with the advancement of radiological science, Sir Godfrey Hounsfield invented computed tomography (CT) in the early 1970s, and this starts the true era of 3D imaging. Modern medical-grade CT scans, with the assistance of computers, will compile these 2D image slices and reformat them into true 3D images that are both stunning and vivid.
Within the last quarter of a century, another 3D imaging format emerged: Cone Beam Computed Tomography (CBCT). CBCT images are acquired through a 360-degree pendular movement of a cone beam, and the images are reconstructed using the Feldkamp algorithm to produce 3D images. Unlike traditional medical CT scans, the CBCT effective radiation dose is significantly less (about 150 to 200 times less radiation).
At OPDSF Orthodontics, we have the state-of-the art CBCT machine. The NewTom VGI-Evo delivers clear, diagnostic 2D and 3D images from a single scan with one of the lowest radiation outputs and much less than an orthodontic traditional series of lateral ceph, panorex, and full-mouth periapicals and bitewings. Moreover, we are able to localize and minimize the radiation dosage with proper calibration, select the appropriate field of view, and prescribe an even lower and diagnostic radiation dosage appropriate to the age and size of the patient. In the EcoScan, our radiation dose can be reduced as much as 40% from the regular scan. We follow the ALARA (As Low As Reasonably Achievable) rule to minimize radiation dose and provide a lead-free protective garment to protect our patients from any unwanted radiation during the exposure period.
CBCT imaging allows us a more conservative and comprehensive view of the dentofacial structures, including the soft tissue structures that were previously difficult or impossible to evaluate. Some common applications of this new technology are listed below:
- Analyze the airway that may indicate the possibility of sleep apnea.
- Able to detect pattern and rate of facial growth, including any subtle asymmetry.
- Detect abnormalities, e.g. supernumerary teeth, impacted third molars (wisdom teeth), missing teeth, abnormal eruption path and primary failure of eruption.
- Detect root foreshortening in other spatial planes that were not available conventionally.
- Able to predict with confidence the limitations of orthodontic and surgical movements.Accurately evaluate the jaw joints (TMJs), e.g., jaw joint spaces, atrophy of condylar surfaces and osteoarthritis.
- Visualize unparalleled imagery of the entire dentofacial and soft tissue simultaneously.
- Determine the bone housing levels associated with gum problems (periodontitis).
- Asses damage to traumatized bone or teeth, e.g., root fracture.
- Evaluate the extent of periapical lesions associated with a root canal (endodontics).
- Review the paranasal sinuses clearly, e.g., mucocele.
- Assess the quality and site of bone structure for future dental implants.
- Determine the maturation and growth potential of the dentofacial structures.
- Precisely determine the root positioning to allow accurate orthodontic correction.
- Accurately measure anatomical structures, e.g., thickness of upper palatal shelf, determination for skeletal mini pins and optimal sites for mini pin (Temporary Anchorage Device, TAD) placements.
CBCT images, in conjunction with 3D interactive images from the Invisalign® iTero®, completes the entire armamentarium needed by any orthodontist to fully, appropriately and confidently diagnose and treat any malocclusion presented by a patient of any age. CBCT imaging is the new revolution in dentistry, especially for orthodontics, and it has positively affected treatment outcomes and provided treatment optimizations.