Ultrasound examination for the detection of simulated periapical bone lesions in bovine mandibles: an ex vivo study

Abstract

Aim: To evaluate the accuracy of ultrasound examination (USE) for the detection of artificial bone defects in bovine mandibles in the absence of complete erosion of the cortical bone plate and to determine the minimum cortical thickness that constitutes a barrier for ultrasound waves.

Methodology: Sixty bovine mandibular anatomical blocks were harvested and uniformly distributed amongst six experimental groups. The negative control consisted of blocks with no intra-bony defects, whereas the positive control consisted of blocks with an artificial lesion of 2 mm diameter that perforated the buccal cortical bone plate. Two experimental groups comprised blocks with small (2 mm) and large (5 mm) artificial defects created under a cortical plate thinned to varying thicknesses. Two additional groups had small (2 mm) and large (5 mm) artificial defects that did not involve the cortical plate. After USE, the scans were saved and submitted to three blinded examiners. Sensitivity, specificity, predictive values and receiver-operating characteristics (ROC) were analysed. The significance of the findings (P < 0.05) was appraised using the chi-square statistics with the Yates correction, whilst the intra- and inter-examiner agreements were evaluated through Kappa statistics.

Results: USE was associated with high sensitivity (97.3%) and negative predictive value (89%), and a perfect score for specificity and positive predictive value. The ROC curve analysis revealed an accuracy of 97.8%. The k-values were 0.86 and 0.89 for the first and second examinations, respectively, demonstrating very high inter-observer agreement. The intra-observer agreement was also high (k-value = 0.92). A significant correlation between the echographic diagnosis and the presence or absence of artificial intraosseous lesions in the anatomical blocks of bovine mandibles was observed (P < 0.0001).

Conclusions: USE was highly accurate and reliable for the detection of artificial lesions within bovine mandibles, regardless of the thickness or presence of the cortical plate.

Keywords: Endodontics; apical periodontitis; bone lesions; ultrasound examination; ultrasound imaging.