Cone Beam Computed Tomography: A Useful Tool in Diagnosis of Bone Island and Implant Insertion Guidance.
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Cone beam computed tomography (CBCT) has been used in dentistry since the mid 1990s. As the name implies, it uses a cone shaped X-ray beam which rotates around the patient to acquire a volumetric data set of the region of interest with a single rotation of the patient. The CBCT volumetric data set comprises a three-dimensional (3D) block of cuboid structures known as voxels, where each voxel represents a specific degree of X-ray beam absorption. Image reconstruction is achieved using computer algorithms ultimately producing 3D images at high resolution. The main advantage of CBCT is that the radiation dosage is considerably less than conventional CT scanning. In addition with most units the patient is scanned in the upright position, and so there is less distortion of the soft tissues in comparison to conventional CT where the patient is supine. This is particularly useful if the facial soft tissues are reconstructed. The literature is replete in clinical applications of CBCT within the oral medicine specialty the clinical applications include imaging of impacted teeth and dental abnormalities, assessment of alveolar bone heights and bone volume, investigation of the temporomandibular joint and so on. The use of CBCT in the field of endodontics has also been described as it is useful for diagnosing canal morphology, assessing root and alveolar fractures, analysis of resorptive lesions and identification of pathology.