CBCT In Orthodontics by CJA

Definition	-3-dimensional image acquisition technique that utilizes a cone shaped x-ray source aimed at a flat panel detector   - X ray beam coupled with the detector rotate together around the patient to produce different volume of sizes of data based on field of view selected -FOV: Small: 5x5cm Medium: 8x8 cm Large: 15x 15cm	Machado, 2015 Makdissi, 2013
Radiation dose	-Panoramic radiograph: 14.2 to 24.3 μSv -Lateral cephalograph: 5.1 to 5.6 μSv -Radiation dose of a CBCT: 30 to 1073 μSv (varies among CBCT units depending on milliampere setting, peak kilovoltage, voxel size, sensor sensitivity, field of view, scan time, and the number of images obtained)	Anne Marie, 2013
Basic principles	-CBCT examinations must be justified (benefits outweigh the potential risks) - CBCT examinations should add new information to aid the patient's management - Routine or screening imaging is unacceptable practice	Anne Marie, 2013
a) Localizing impacted and supernumerary teeth (CBCT recommended )	Indication: - Impacted maxillary canines with inclination exceeding 30° relative to a perpendicular midline  -Suspicion of adjacent root resorption  -Suspicion of canine root dilaceration Justification: -Small volume field of view CBCT  can localize impacted canines accurately through evaluation of their proximity to other teeth and structures (estimate space conditions), determine the follicle size and the presence of pathology,  assess resorption of adjacent teeth to determine extraction pattern, assist in planning surgical access and bond placement, and aid in defining optimal direction for extrusion of these teeth into the oral cavity by eliminating superimposition artefacts and capturing 3D root structures from all possible directions. - Decision to extract or save dilacerated teeth by evaluating the buccolingual direction of the root that will determine the amount and direction of movement required - Detailing morphology of supernumerary teeth and retrievability facilitate decisions on which teeth to retain. - 25% of original treatment plans derived from 2D radiographs are changed after orthodontists viewed impacted teeth in CBCT images with higher confidence in treatment plans (Botticelli, 2011). -Customize treatment and biomechanics for impacted teeth result in increased efficiency and enhanced success rates for tooth retrieval.	Kapila, 2015
b) Assessment of anatomical structures at temporary anchorage device placement (CBCT not recommended )	Justification: -Visualization of neighbouring structures such as tooth roots, sinuses and nerves, evaluation of the quantity and quality of cortical and trabecular bone that may determine primary stability of TADs. * sufficient interradicular space between the maxillary second premolar and the first molar in the buccal alveolar bone near the mucogingival junction and less than 45degrees angulation to the long axis of the tooth.
c) Quantifying magnitude of a defect or deformity in cleft lip and palate (CBCT recommended )	Justification: -Precise information on the numbers, quality and location of teeth in proximity of the cleft site, volume of defect for alveolar bone graft, eruption status and path of canines in grafted cleft site sand diagnosing for implant placement.
d) Evaluating airway morphology in obstructive sleep apnea (CBCT maybe recommended )	Justification: -Measure airway patency by total volume of the patient's airway *Airway area in 2D did not match the airway volume in 3D (Aboudara, 2009)
e) Establishment of “boundary” conditions (CBCT not recommended )	Indication: -Narrow bucco-lingual alveolar bone -Compromised periodontal conditions or gingival anatomy -Translocation tooth Justification: -Establishment of “boundary” conditions (dimensions and morphology of the alveolar bone relative to the tooth root) during orthodontic tooth movement and in the final positioning of teeth
f) Combined surgical-orthodontic treatment (CBCT maybe recommended )	Justification: -Improving differential diagnosis of skeletal, dental or combined malocclusions (identifying the jaw(s) contributing to malocclusion and determining whether the discrepancy is bilateral or unilateral in orthognathic surgery, asymmetry, craniofacial anomaly and open bite cases, condylar position) -Computer-simulated planning utilizing virtual models, soft tissue prediction	Anne Marie, 2013