Revolutionary Dental Imaging Cone Beam Computed Tomography (CBCT)
The last few decades have seen a revolution in maxillofacial imaging due to the introduction of new imaging techniques and their integration into routine dental practice. Cone Beam Computed Tomography (CBCT) is a specifically dedicated cross-sectional imaging modality to view the maxillofacial region in all planes. While the information gleaned from traditional dental radiographs is adequate in most situations, there are limitations of a two- dimensional view.
The three-dimensional (3D) information offers the potential of improved diagnosis for various clinical applications, at lower doses than with ‘medical’ multi-slice CT. The usual CT scanners are expensive, large and difficult to maintain with higher radiation doses. However, dental CBCT occupies considerably less space and can be used in clinical dental practice where the dose considerations and cost are important.
The most common application of CBCT is in implant planning and CBCT offers a range of diagnostic information for all specialties of dentistry including endodontic evaluation of teeth for canal morphology and fractures, surveying impacted teeth and its proximity to surrounding structures, detailed examination of various bony pathologies, periodontal bone loss as well as TMJ examination.
Therefore, with recent advancements such as airway visualization for sleep apnea, 3D cephalometric evaluation, CAD-CAM integration, and image-guided surgical techniques, CBCT has now become indispensable for an accurate diagnosis and treatment planning.
CBCT In Implant Planning
Loss of teeth results in atrophy of the underlying alveolar bone in both the horizontal and vertical plane. Dental implants have now become the most popular and reliable treatment option for replacement of missing teeth, improving health and increasing longevity. However, the success of dental implants depends majorly on the jawbone quantity and quality. Therefore, it is important to measure the alveolar process precisely so that the proper system may be chosen.
To improve the overall success of implant therapy with possible reduction in surgical and postoperative implant complications, the implant surgeon should have 3D information of bone volume and topography, prior to the implant placement.
Also, the selection of the implant site is crucial to the success or failure of the implant. Thus, the implant site must be evaluated to determine the quantity and quality of available bone, the angulation of the alveolar process, the relationship of the site to anatomic structures and the possible problems in the area. (Table 1)
Indications For A CBCT Scan In Implant Planning (Adapted From DCNA 2015)
- Three dimensional assessment of alveolar ridge morphology
- Analysis of quality of bone Evaluation of dimensions (width and height) of available bone for implant placement
- Analysing whether sinus augmentation or bone grafting (block/particulate) is needed
- Assessing previous trauma in the region
- Identification of pathology and vital anatomic structures
- Evaluation of any impacted tooth in the region of implant placement
- Planning with surgical guides using CBCT
- Patient education
- Estimating degree of osseointegration of implants
CBCT In Oral Surgical Cases
One of the most common diagnostic applications of CBCT in oral surgery is the extraction of impacted teeth and surgical management of various pathologies manifesting in the jaws. Coloured marking of the nerve canal with the help of special software can help in better pre-operative establishment of the connection of the third molar with the mandibular canal which can help in minimizing the risk of nerve injury.
CBCT can help in accurately visualizing the position of an impacted canine, supernumerary or other impacted teeth with all its roots and the relationship to the nerve/foramen/sinus wall. It also helps in picturing the bucco-palatal relationship for surgical accessibility as well as the proximity and effect on the adjacent/overlying teeth.
CBCT also plays an important role in establishing the exact extent, size, relative nature and relative density of a lesion (radiolucent/radiopaque) and the effect on surrounding structures for accurate surgical planning and approachability.
CBCT in Endodontics And Periodontics
There is compelling evidence that shows the role of CBCT in planning of periapical surgery, characterisation, and localization of root canals, detection and treatment of root fractures in the extracted teeth.
Following table (Table 2) enlists the numerous ways in which CBCT can serve as an important diagnostic tool.
Indications For A CBCT Scan In Endodontics
- Abnormal root as well as canal morphology
- Missed canals (specially MB2 canals)
- Calcified canals
- Extra root
- Coronal and root fractures (horizontal more than vertical)
- Characterization of internal and external resorption
- Extent and nature of periapical pathology and effect on surrounding bone and teeth
- Discontinuity in lamina dura and widening of PDL space
- Secondary caries
Diagnostic imaging, especially Cone Beam Computed Tomography, is the field where the winds of change are blowing, wherein the future lies. An excellent training and education in CBCT is mandatory for oral maxillofacial radiologists and general dentists to adequately use CBCT for benefits. The benefit of using CBCT must outweigh the risks associated with radiation dosage, thus aligning with the principle of Justification of Radiation dosing.