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Dental Tribune Middle East & Africa Edition

Centre for Advanced Professional Practices (CAPP)is an ADA CERP Recognized Provid- er. ADA CERP is a service of the American Dental Assotiation to assist dental profession- als in identifying quality providers of continue dental education. ADA CERO does not approve or endors individuals courses or instructors, nor does it imply accseptance of credit hoiurs by boards of dentistry. F or nearly 100 years, dentists have relied on 2-D radiographic imaging for diagnosis and treatment plan- ning. With the 1999 introduction of cone-beam computed tomography (CBCT), all dentists now have tools available for more accurate diagnosis and treatment.1 The ability to look at a tooth in any direc- tion and orientation, as well as in 3-D, elim- inates much of the guesswork commonly experienced with 2-D radiographs. We have been limited in most cases to only a buccal-lingual view provided by periapi- cals, bitewings and panoramic radiographs with the occasional axial view of an occlu- sal film. Medical CT scans and images be- gan in the early 1970s and were sometimes used by dentists, offering our first multi- planer views.2 The adoption of 3-D cone-beam imaging is appropriate and has important advantag- es for all modalities of dentistry. From ev- ery specialist to the general dentist, the in- creased amount of radiographic informa- tion as well as increased accuracy will aid in the most sound diagnosis possible. CBCT description CBCT is a single or partial rotation of an X- ray source around the head, capturing X- rays on various flat panel arrays and sen- sors. The information is converted to a se- ries of axial slices by computed tomogra- phy and stored as virtual anatomy in the computer. With the use of sophisticated software, the dentist is able to view information in sev- eral different views, including: axial slic- es (head-to-toe orientation), coronal slices (front-to-back orientation), saggital slices (side-to-side orientation) all known as mul- tiplaner reconstructions (MPR). The thick- ness of each slice can be varied to include more or less information. Because the voxels (volumetric pixels 3-D) are isotropic, other MPR images can be gen- erated by slices drawn at any angle, curve or thickness through the scan to view areas critical to the final diagnosis.3,8 The final view offered by CBCT is a 3-D view that can be rotated and viewed in any direction. Once again through software manipula- tion, 3-D images can be viewed as con- ventional radiographs, maximum intensi- ty projections (MIP), soft-tissue projections and a variety other views. This nearly endless ability to manipulate the data aids in the diagnosis and iden- tification of disease, nerve canals, sinus morphology, dental caries, bone densi- ty, fractures, endodontic pathology, im- plant placement criteria, periodontal de- fects, bone pathology, fractured teeth, iat- rogenic trauma, TMJ morphology and dis- ease, third-molar position and many more healthy or diseased conditions. Early CBCT adoption with implants The first and primary use of CBCT for ear- ly adopters was implant placement. As the scope and the value of the information be- came better known, dentists of all branch- es began to see the value of MPRs and 3-D renderings including periodontics, end- odontics, oral surgery, treatment of TMJ, orthodontics, implantology and general dentistry.1,7,8 Clinical periapical and panoramic radio- graphs for the placement of implants can be misleading with elongation, foreshort- ening, superimposition and geometrical- ly incorrect data.7,8 A look at the implant in the periapical shows no obvious disease to an existing integrated implant. Clinically, a buccal fistula was present with exudate and slight pain. The CBCT scan (Fig. 1) re- veals a more accurate view showing a buc- cal defect on a saggital MPR. A surgical flap revealed a dehiscence of the coating of the implant. Removal of the foreign body resulted in an asymptomatic and healthy patient The evaluation of the available bone for the initial implant placement can be crucial for the long-term success of the case. If there is inadequate bone available, grafting may be a necessity. CBCT studies render the most accurate information available at a low ra- diation dose. The periapical shows an obvi- ous lack of bone height, but does not show the buccal-lingual dimensions or an accu- rate view of the sinus morphology (Fig. 2). The MPR view of the CBCT shows all neces- sary measurements to perform the sinus lift and grafting with the immediate placement of the implant fixture (Fig. 3). Three-dimen- sional views show the floor of the sinus and any soft-tissue pathology (Fig. 4). Having accurate measurements in all dimensions is an advantage of CBCT scanning. The digitized occlusion: Using something old with something new mCME articles in Dental Tribune have been approved by HAAD as having educational content for CME credit hours. This article has been approved for 2 CME credit hours. 2 Hours even though other clinical findings and symptoms are abnormal. The patient pres- ents several months post root-canal treat- ment with pain on palpation and pressure and avoids this side of the mouth. A periapical radiogragh shows minimal pathology (Fig. 6). The roots appear to be filled and a small puff of sealer extends through the apex of the mesial roots. The distal root structure and fill appear normal. There is little indication of periapical radio- lucency only a widening of the periodontal ligaments of the mesial roots. A CBCT scan reveals a completely different picture. The coronal MPR reveals a short fill near the apex of the mesial lingual root and a large radiolucency (Figs. 7, 8) not vis- ible on the periapical radiograph (Fig. 6). Missed canals are difficult to see in a buc- cal-lingual projection of the periapical ra- diograph as one canal is superimposed on the other (Fig. 9). Often, as viewed in this radiograph, we see periapical patholo- gy with an apparent normally filled canal. CBCT scans allow dentists to look for pa- thology in MPR planes to identify the ac- tual problem before invasive procedures are performed on the patient. The axial view shows a lingual canal exists and is un- treated. The coronal view confirms the di- agnosis and treatment can be completed (Fig. 10). Today’s endodontists, as well as general dentists, are benefiting from the diagnos- tic capabilities of the high-resolution CBCT scanners available over conventional 2-D periapical.5,6 Oral surgery Oral surgery, with its inherent invasive nature, can be better served using CBCT with MPR as well as 3-D images. The abil- ity to perform virtual surgery is a benefit to both the doctor and the patient. Doctors have the advantage of seeing morphology and landmarks in real time and space with accurate measurements, and patients will gain a better understanding of the prob- lems and the solutions their doctors are of- fering them. Third-molar extractions can be risky based on 2-D and panoramic radiographs. These radiographs can often superimpose nerves and sinuses over root structures. Dentists using 2-D radiographs must often rely on experience to assess the risks of iatrogen- ic trauma. The use of CBCT with MPRs and 3-D images reduces any guessing as well as the chance for any permanent damage to the patient. With the adoption of CBCT, the judgment is based on solid evidence and the risk will decrease. A panorex of the superimosed third mo- lars gave no solid evidence the canal lies between the roots. It is only with the use of CBCT and the MPRs that the nerve can accurately be seen traversing between the mesial buccal and mesial lingual root (Fig. 11).4,5 Other surgical advantages include the identification and the position of super- numerary or impacted teeth. The images show accurate positions and show defin- itive morphology that will aid in remov- Fig. 5 Axial MPR showing mesial buccal roots in first, second and third molars. Fig. 1 Fig. 2 Fig. 3 Fig. 1 Saggital CBCT MPR showing bone defect at point of dehiscence of the implant coating. Fig. 2 Periapical does not show the sinus anatomy or the width of the bone. Fig. 3 MPR showing post-op of sinus graft and implant placement. Fig. 5 Fig. 4 The 3-D CBCT showing anatomy of the max- illary sinuses. Fig. 4 CBCT and endodontics Endodontics is a field that is rapidly adopt- ing the use of CBCT and for good reason. The inherent geometric deficiencies of 2-D radiographs make the CBCT scan a valu- able adjunct to investigate the root mor- phology in both 3-D and MPR. The typical periapical will show superimposed canals in the anteriors, bicuspids and molars as well as unwanted bone densities both buc- cal and lingual to the affected tooth making the image quality poor. The ability to view MPR slices in cross-sec- tion, long axis and oblique directions gives the ability to follow all canals in any direc- tion and show their relationship and mea- surements from other known structures. This virtual tour of the root morphology is a great benefit to the final treatment out- come (Fig. 5).3,4 Post root-canal infection can be difficult to diagnose with the standard periapical. The endodontic fills may appear to be normal 10 MEDIA CME Dental tribune Middle East & Africa Edition | March-April 2013