CBCT is a useful tool for imaging the craniofacial area that produces more realistic images that facilitate interpretation. All the previous conventional and digital intraoral and extra-oral procedures, as they were two dimensional (2D) projections, suffer from several limitations. These limitations were magnification, distortion, superimposition and misrepresentation of structures. CBCT has achieved a transition of dental imaging from 2D to 3D images. Moreover, the application of sophisticated software, contribute to the reestablishment of imaging sciences role. Now Dento-maxillofacial radiology has been expanding from the diagnosis field to image guidance of operative and surgical procedures. As a consequence the treatment outcome is enhanced. As a result of the constant scientific research in the medical imaging field, CT scanners have been tremendously enhanced.
Selection of CBCT is based on the individual patient’s history and a clinical examination. A ‘routine’ (or ‘screening’) examination is defined as one in which a radiograph is taken regardless of the presence or absence of clinical signs and symptoms. Choosing CBCT for a patient is based upon consideration of the prevalence of diseases, their rates of progression and the diagnostic accuracy of CBCT, compared with traditional techniques, for the application in question. Consulting guidelines facilitates the process of selecting radiographs
Many children seek orthodontic treatment. Usually the treatment starts at the time period of mixed dentition stage. Orthodontic patients may present abnormalities in eruption pattern, tooth position or signs of crowding. Radiographs may be required to determine the presence, absence, position and condition of teeth.
Justification of X-ray examinations in children is especially important because of the higher risks associated with exposure in children. Traditional radiological examination of children undergoing orthodontic assessment includes a panoramic radiograph, supplemented by a lateral cephalometric radiograph in specific circumstances. Intra-oral radiographs are also used according to patient-specific needs.
In recent years, however, the availability of CBCT has led to this technique being used by some clinicians as a means of radiological examination.
The applications of CBCT in assessment of the developing dentition for orthodontics will be considered under two broad headings
A frequent application of CBCT is for assessment of the position of an unerupted tooth, particularly where the tooth is impacted. “Impaction is defined as a failure of tooth eruption at its appropriate site in the dental arch within the normal period of growth based on clinical and radiographic assessment”. Third molars are the most frequently impacted teeth, followed by the permanent maxillary canines. Impacted third molar and related symptoms are a frequent problem that the dental practitioner has to deal with. In cases that the anatomy of the third molar is not extremely abnormal and the tooth in not correlated with the mandibular canal, surgical procedure is not a hazardous.
In cases concerning the lower third molar in which there is a relationship between the roots and the mandibular canal, a careful preoperative evaluation is needed. In such cases the CBCT examination could provide us with valuable information that the conventional radiographic techniques could not due to their limitations. In particular, it is important to know the exact position and orientation of the impacted molar, as well as its relation with other anatomical structures, prior to the tooth removal, since there is a strong possibility to occur a permanent or temporary damage to the inferior alveolar nerve.
Also the CBCT allows for a more precise analysis of the extent of the pathology related to the impacted tooth. Consequently it is possible to design treatment strategies that would result in less invasive surgical intervention.
In cases of impacted teeth, an integral aspect of the assessment is often the accurate identification of any resorption of adjacent teeth. “Root resorption is defined as a condition of dental complication associated with either a physiological or pathological activity of the tooth resorbing cells, which results in loss of cementum and /or dentine”. Root resorption is very difficult to treat and usually requires extraction of the affected tooth .Such a situation is most often seen where maxillary canines are ectopic and incisor roots are suspected of having undergone resorption.
For the localized assessment of an impacted tooth (including consideration of resorption of an adjacent tooth) where the current imaging method of choice is conventional dental radiography, CBCT may be used when the information cannot be obtained adequately by lower dose conventional (traditional) radiography. Clinical reports using 3-dimensional imaging have shown that the incidence of root resorption of teeth adjacent to impacted teeth is greater than previously thought.
CBCT allows the 3D visualization of the craniofacial skeleton. The overlay-free visualization of structural and anatomic relationships permits the accurate evaluation of the anatomic structures.
CBCT may be preferred for the assessment of cleft palate where radiation dose is lower. CBCT in patients with cleft lip and palate is useful for
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