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2 Cone Beam Computed Tomography Recommendations

       Shawneen M. Gonzalez

Introduction

      This chapter covers cone beam computed tomography recommendations and guidelines regarding use and imaging. The areas covered include recommendations from American endodontics, orthodontics, and periodontics specialty organizations along with sample cases.

Endodontics

      The American Association of Endodontics (AAE) and the American Academy of Oral and Maxillofacial Radiology (AAOMR) have come out with two position papers regarding cone beam computed tomography (CBCT) use in endodontics.

      2010 Position Paper

      There were two main imaging goals from the 2010 paper – field of view (FOV) and resolution/voxel size. A small/limited FOV and a resolution/voxel size of 0.2 mm or smaller is recommended. This combination allows better visualization for small changes to the periodontal ligament space, bone, and teeth. When using CBCT, it should not be used for routine use and should be based on a patient’s history and clinical examination. Before capturing a CBCT scan, it is important to receive patient consent and explain the risks and benefits of the imaging modality. Last, the entire CBCT volume must be interpreted.

      2015/2016 Update

      The updated position paper gives 14 case examples and whether a limited FOV CBCT or intraoral 2D imaging is recommended. They are separated into different categories: diagnosis, initial treatment, nonsurgical treatment, surgical retreatment, special conditions, and outcome assessment.

      Diagnosis

      1 = Intraoral radiographs should be considered for the evaluation of endodontic patients.

      2 = Limited FOV CBCT should be considered when there are nonspecific clinical signs or symptoms with an untreated or previously endodontically treated tooth.

CBCT imaging has increased sensitivity in the detection of periapical pathosis (Figure 2.1) compared to intraoral radiographs. In the presence of clinical signs with the absence of intraoral radiographic findings, a CBCT may be recommended to rule out or rule in possible periapical pathosis. It is important to thoroughly check all of the teeth on a scan because early periapical pathosis has been noted on CBCT prior to detection on intraoral radiographs. Sagittal and cross‐sectional views are the recommended views for detecting periapical pathosis.

Figure 2.1. (a) Sagittal view showing a distal dilaceration of the mesio‐buccal root of the maxillary first molar with a short endodontic filling and rarefying osteitis (white arrow). (b) Periapical radiograph showing a resulting apicoectomy after the findings on the CBCT scan.

      Initial Treatment

3 = Limited FOV CBCT should be considered when evaluating teeth with potential extra canals or complex morphology (excludes maxillary incisors) (Figure 2.2).

Figure 2.2. Coronal view showing a maxillary premolar with an unfilled palatal root (white arrow) and apical rarefying osteitis.

      4 = Limited FOV CBCT should be considered to identify and localize calcified canals.

      5 = Intraoral radiographs should be considered for immediate postoperative evaluation.

      Nonsurgical Treatment

      6 = Limited FOV CBCT should be considered if the clinical exam and intraoral radiographs are inconclusive for detecting a vertical root fracture.

Vertical root fractures are difficult to diagnose on intraoral radiographs with localized bone changes visualized first (Figure 2.3). The bone changes typically present with J‐shaped bone loss around the root with the fracture. CBCT imaging has increased sensitivity in detecting vertical and horizontal root fractures (Figures 2.4 and 2.5). Coronal, sagittal, and cross‐sectional views are the recommended views for detecting vertical root fractures. One concern when evaluating

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