DTME1010

Media CME DENTALTRIBUNE Middle East & Africa Edition6 _Two-dimensional imaging modalities have been used in dentistry since the first intra-oral radiograph was taken in 1896. Significantprogressindentalim- aging techniques has since been made, including panoramic im- aging and tomography, which enable reduced radiation and faster processing times. How- ever, the imaging geometry has not changed with these com- monly used intraoral and panoramic technologies. Cone-beam computed to- mography (CBCT) is a new med- ical imaging technique that gen- erates 3-D images at a lower cost and absorbed dose compared with conventional computed to- mography (CT). This imaging technique is based on a cone- shaped X-ray beam centred on a 2-D detector that performs one rotation around the object, pro- ducing a series of 2-D images. Theseimagesarere-constructed in 3-D using a mo - dification of the original cone-beam algo- rithm developed by Feldkamp et al. in 1984.1 Images of the cranio- facial region are often collected with a higher resolution than those collected with a conven- tional CT. In addition, the new systems are more practical, as they come in smaller sizes.2 Today, much attention is fo- cused on the clinical applica- tions—diagnosis, treatment and follow-up—of CBCT in the vari- ous dental disciplines. The goal of the following systemic review is to review the available clinical and scientific literature pertain- ing to different clinical appli - cation of CBCT in the dental practice. _Materials and methods Clinical and scientific litera- ture discussing CBCT imaging in dental clinical applications was reviewed. A MEDLINE (PubMed) search from 1 January 1998 to 15 July 2010 was con- ducted. Cone-beam computed tomography in dentistry was used as key phrase to extend the search to all the various dental disciplines. The search revealed 540 papers that were screened in detail. Owing to a lack of rele- vance to the subject, 406 papers were excluded. Thus, the sys- temic review consisted of 134 clinically relevant papers, which were analysed and categorised (Table I). _Analysis Oral and maxillofacial surgery CBCT enables the analysis of jawpathology,3–11 theassessment of impacted teeth (Fig. 1), super- numerary teeth and their rela- tion to vital structures, 6,12–21 changes in the cortical and tra- becular bone related to bisphos- phonate-associated osteonecro- sis of the jaw5,22–23 and the assess- ment of bone grafts.24 It is also helpful in analysing and assess- ing paranasal sinuses6,25 and ob- structive sleep apnea.27–28 As the images are collected from many dif - ferent 2-D slices, the system has proven its superi- ority in overcoming superimpo- sitions and calculating surface distances.28–29 This advantage made it the technique of choice in mid-face fracture cases,30–31 orbital fracture assessment and management32 and for inter-op- erative visualisation of the facial bones after fracture.33–34 Since it is not a magnetic resonance technique,itisthebestoptionfor intra-operative navigation dur- ing procedures, including gun- shot wounds.35–36 CBCT is largely used in or- thognathic surgery planning when facial orthomorphic sur- geryisindicatedthatrequiresde- tailed visualisation of the inter- occlusal relationship in order to augment the 3-D virtual skull model with a detailed dental sur- face. With the aid of advanced software, CBCT facilitates the vi- sualisation of soft tissue to allow forcontrolofpost-treatmentaes- thetics, for example in cleft palate cases to evaluate lip and palate bony depressions.37–42 Research is underway to as- sess its ability to detect salivary gland defects.43 Honda et al.44 de- scribeaclinicalcaseinwhichthe time needed to complete a tooth auto-transplant case was signifi- cantlyshortenedowingtotheap- plication of CBCT. Endodontics CBCT is a very useful tool in diagnosing apical lesions (Figs. 2a & b).21,45–56 A number of studies have demonstrated its ability to enable a dif fe - rential diagnosis of apical lesions by measuring the density from the contrasted images of these lesions, in whether the lesion is an apical granuloma or an apical cyst (Figs. 3a & b).49,55–57 Cotton et al.46 used CBCT as a tool to assess whether the lesion was of en- dodontic or non-endodontic ori- gin. CBCT also demonstrated su- periority to 2-D radiographs in detecting fractured roots. Verti- cal and horizontal root fracture detection is described in several clinical cases.21,46,55–59 It is also agreed that CBCT is superior to peri-apical radiographs in de- tecting these fractures, whether they are bucco-lingual or mesiodistal.60–61 In cases with inflammatory root resorption, lesions are de- tected much easier in early stages with CBCT compared to conventional 2-D X-ray.21,62 In othercases,suchasexternalroot resorption, external cervical and internal resorption, not only the presence of resorption was de- tected, but also the extent of it.21,46,54,56,63–64 CBCT can also be used to de- termine root morphology, the number of roots, canals and ac- cessory canals, as well as to es- tablishing the working length and angulations of roots and canals.21,25,46,55–56,58,65–67 It also is accurate in assessing root-canal fillings.47,51,56,58 Owing to its accu- racy,itisveryhelpfulindetecting the pulpal extensions in talon cusps68 and the position of frac- tured instruments.69 Itisalsoareliabletoolforpre- surgical as - sessment of the proximityofthetoothtoadjacent vitalstructures,sizeandextentof lesions, as well as the anatomy and morphology of roots with very accurate measure- ments.21,46,48,50,54–58,69–72 (mCME articles in Dental Tribune (always page 6) has been approved by HAAD as having educational content acceptable for (Category 1) CME credit hours. Term of ap- proval covers issues published within one year from the distribution date (September, 2010). This (Volume/Issue) has been approved by HAAD for 2 CME credit hours. 2 Hours CBCT applications in dental practice: A literature review Authors_ Dr Mohammed A. Alshehri, Dr Hadi M. Alamri & Dr Mazen A. Alshalhoob, Saudi Arabia Fig. 1 Fig. 2a Fig. 2b Fig. 3bFig. 3a Fig. 4bFig. 4a Figs. 3a & b_Apical cyst shown as orthopantomogram (a) and CBCT (b). Fig. 4a_Orthopantomogram for a full-mouth rehabilitation case. Only limited data can be obtained from this image. Fig. 4b_CBCT images for the same patient. Data obtained from these images regarding bone quality, implant length and diameter, implant location and proximity to vital structures is magnificent. Specialty Number of articles in % Oral and maxillofacial surgery 36 26.86 Endodontics 32 23.88 Implantology 22 16.42 Orthodontics 16 11.94 General dentistry 14 10.45 Temporomandibular joint disorder 8 5.97 Periodontics 5 3.73 Forensic dentistry 1 0.75 Table I Fig. 1_Impacted teeth in close proximity to vital structures should be evaluated with CBCT. Figs. 2a & b_Peri-apical lesion shown as peri-apical radiograph (a) and CBCT (b; images courtesy of Dr Fred Barnett).