Detection of Horizontal Root-fracture: Comparison of CT and Intra-oral Radiography

Objective: To compare the accuracy of intraoral radiography, multi detect helical CT (MDHCT; slice thickness: 0.63 and 1.25 mm) and limited cone beam X-ray CT (LCBCT) for the detection of horizontal tooth root fracture.

Method: Twenty-eight maxillary anterior teeth (bilateral first and second incisors) in the seven beagle dogs were extracted with local anesthesia under sodium pentobarbital anesthesia. Thirteen random selected teeth out of 28 were artificially induced to horizontal root fracture, other 15 teeth were not. After sacrificing the dogs, all teeth were excised with surrounding maxillary bone and soft tissues.  The width of the fracture line was measured using a micro-CT device, and then the specimens were examined by the above-mentioned four kinds of radiographies. The intraoral radiographs were observed on a light-box, and the reconstructed coronal images obtained by MDHCT and LCBCT were observed on a monitor. Diagnosis of root fracture was based on direct visualization of radiolucent line in each image by six oral and maxillofacial radiologists.

Result: The actual width of the fracture line was 0.243 ± 0.069 mm.  Inter-observer agreement in LCBCT was higher than those in other three radiographs.  LCBCT showed the highest sensitivity, negative predictive value, and diagnostic accuracy (true positives + true negatives) for detection of the fracture line, followed by MDHCT (slice thickness: 0.63 mm); no significant difference was noted between MDHCT (slice thickness: 1.25 mm) and intraoral radiography.  No significant difference was found in specificity or positive predictive values among the four methods.

Conclusion: LCBCT is considered more useful than other three radiographies as the diagnostic imaging of the horizontal tooth root fracture.