Diagnosis of cracked teeth using cone-beam computed tomography: literature review and clinical experience

Abstract

Cone-beam computed tomography (CBCT) has been widely used in diagnosis of vertical root fractures (VRFs) in recent years. According to the American Association of Endodontists (AAE) classification, there are five types of cracked teeth and VRF is one of them. Due to the variability and overlapping of the cracks and fractures, some narrow fractures on the roots of VRFs could not be detected by CBCT, and some wide cracks on the crown of cracked teeth could be detected by CBCT. In this review, we firstly discussed the value of CBCT in the diagnosis of the AAE five types of cracked teeth and presented CBCT manifestations of some typical cases. Secondly, we summarized the factors influencing the diagnosis of cracks/fractures using CBCT, namely, CBCT device-related factors, patient-related factors, and evaluator-related factors. The possible strategies to improve the diagnostic accuracy in the clinic practice are also discussed in this part. Finally, we compared the differences of root fractures with lateral canals and external root resorption on CBCT images.

Keywords: Cone-beam computed tomography; Cracked teeth; Cracks/fractures; Diagnosis; Vertical root fracture.

Figure 1.

(a, b) Axial images showing tooth 16 with a complete fracture of the mesiopalatal cusp (arrows). (c, d) Coronal and sagittal reconstruction images showing that the fracture initiates from the crown of the tooth and extends subgingivally (arrows).

Figure 2.

A case of cracked tooth progressing to split tooth (tooth 36). (a1) Periapical radiograph (PR) showing extensive bone resorption around the root. (a2) Axial image showing a mesiodistal hair-like hypodense line (arrow) that is present on the crown but disappears on the root. (a3) Coronal reconstruction image showing severe buccal and lingual alveolar bone resorption around the root. Cracked tooth with acute inflammation was diagnosed after an incision was made on the periodontal abscess; however, the patient did not undergo further treatment. (b1) PR taken 1 year after the primary referral at our hospital showing more extensive bone resorption around the root. (b2) An obvious mesiodistal fracture line (arrow) can be seen on the occlusal surface. (b3) The extracted tooth has split completely (arrow).

Figure 3.

A split tooth (tooth 25). (a1, a2, a3) Axial image showing a mesiodistal hair-like hypodense line (arrow) that is present on the crown but gradually disappears on the root. (a4) Coronal reconstruction images showing a fracture line extend from the occlusal surface to the pulp cavity (arrows). (b1, b2, b3, b4) A fracture line could be found from occlusal surface to the 2/3 root (arrows).

Figure 4.

(a, b) Axial images clearly showing a complete and displaced fracture (arrows) of the mesial root of tooth 36 with alveolar bone resorption around the root. (c) Sagittal reconstruction image showing broadening of the mesial root canal (arrow).

Figure 5.

(a) PR showing a low-density shadow around the distal root of tooth 46. (b) Sagittal reconstruction image showing alveolar bone resorption around distal root (arrow). (c) The extracted tooth showing the fracture line (arrow). (d1–d3) Subtle irregular hypodense line (arrows) on the distal root without displacement of the two fracture segments.

Figure 6.

(a–c) No obvious fracture lines can be seen in the cervical, middle, and apical thirds of the mesial root of tooth 36 on axial images. (d) Coronal reconstruction image showing vertical alveolar bone resorption on the buccal side. (e) Periodontal examination reveals deep periodontal pockets on the buccal side-of the mesial root measuring approximately 11 mm. (f) Periodontal exploration reveals a longitudinal fracture line on the buccal side-of the mesial root.

Figure 7.

(a, b) Axial images of tooth 16 showing a hypodense line (arrow) extending from the root canal to the surface of the palatal root, similar to a VRF; however, the hypodense line is present on only one slice and appears as a round hypodense canal closer to the surface of the root on the next axial slice. (c) Coronal reconstruction image clearly showing a lateral canal (arrow) of the palatal root.

Figure 8.

(a, b) Axial images showing a broad, low-density defect similar with root fracture (arrows). (c) However, sagittal and coronal reconstruction images show an irregular absence of root surface, which indicates external root resorption of palatal root (arrows) and not a vertical root fracture. (d) The extracted tooth shows that the palatal root has external root resorption(arrow).