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cone beam international magazine of cone beam dentistry

08 I I CE article _ application of 3-D imaging The ability to view MPR slices in cross-section, long axis and oblique directions gives the ability to follow all canals in any direction and show their relationship and measurements from other known structures. This virtual tour of the root morphology is a great benefit to the final treatment outcome (Fig. 5).3, 4 Post root-canal infection can be difficult to di- agnose with the standard periapical. The endodon- tic fills may appear to be normal even though other clinical findings and symptoms are abnormal. The patient presents several months post root-canal treatment with pain on palpation and pressure and avoids this side of the mouth. A periapical radiogragh shows minimal pathol- ogy (Fig. 6). The roots appear to be filled and a small puffofsealerextendsthroughtheapexofthemesial roots. The distal root structure and fill appear nor- mal. There is little indication of periapical radiolu- cency only a widening of the periodontal ligaments of the mesial roots. A CBCT scan reveals a completely different picture.ThecoronalMPRrevealsashortfillnearthe apex of the mesial lingual root and a large radio- lucency (Figs. 7 & 8) not visible on the periapical radiograph (Fig. 6). Missed canals are difficult to see in a buccal- lingual projection of the periapical radiograph as one canal is superimposed on the other (Fig. 9). Of- ten, as viewed in this radiograph, we see periapical pathology with an apparent normally filled canal. CBCT scans allow dentists to look for pathology in MPR planes to identify the actual problem before invasive procedures are performed on the patient. The axial view shows a lingual canal exists and is untreated. The coronal view confirms the diagnosis and treatment can be completed (Fig. 10). Today’sendodontists,aswellasgeneraldentists, are benefiting from the diagnostic 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.Theabilitytoperformvirtualsurgeryisaben- efit to both the doctor and the patient. Doctors have theadvantageofseeingmorphologyandlandmarksin realtimeandspacewithaccuratemeasurements,and patients will gain a better understanding of the prob- lemsandthesolutionstheirdoctorsareofferingthem. Third-molar extractions can be risky based on 2-Dandpanoramicradiographs.Theseradiographs canoftensuperimposenervesandsinusesoverroot structures. Dentists using 2-D radiographs must often rely on experience to assess the risks of iatro- genic 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 molars gave no solid evidence the canal lies between the roots. It is only with the use of CBCT and the MPRs that thenervecanaccuratelybeseentraversingbetween themesialbuccalandmesiallingualroot(Fig.11).4, 5 Othersurgicaladvantagesincludetheidentifica- tionandthepositionofsupernumeraryorimpacted teeth.Theimagesshowaccuratepositionsandshow definitivemorphologythatwillaidinremovalofthe proper teeth (Fig. 12). Knowing the exact position of many of these teeth is a benefit to both the doctor and patient. It will lead to the most precise surgical path and the least invasive procedure. _Periodontics Theexplanationofperiodontalproblemsareoften misunderstoodbythepatient.Asdoctorswetalkabout Fig. 9_Periapical showing a normal fill with a radiolucency. Fig. 10_Coronal MPR showing the superimposed lingual root unfilled. Fig. 11_Coronal MPR showing nerve between roots of the third molar. cone beam1_2014 Fig. 9 Fig. 10 Fig. 11 CBE0114_06-09_McEowen 31.01.14 15:49 Seite 3