The Effect of Gamma Values in Detection of Internal Root Resorption in CBCT Images: An In Vitro Study

Accurate and early diagnosis of internal root resorption is essential for determining the outcome of treatment and prognosis. Several digital processing algorithms have been introduced for the diagnosis of internal root resorption. The aim of the present study was to evaluate the effect of gamma values in the detection of internal root resorption in cone-beam computed tomography (CBCT) images.

A total of 45 healthy extracted single-rooted teeth were selected for the study. The teeth were mesiodistally sectioned at the central groove of their occlusal surface using a diamond disc (0.1 mm diameter). Internal root resorption was simulated at the cervical, middle, and apical regions of a root canal. CBCT images were prepared by gamma values (low, medium, and high modes). Data were analyzed using McNemar tests, Cohen’s kappa coefficient, and the receiver operating characteristic curve. A P value less than 0.05 (typically≤0.05) was considered statistically significant.

Sensitivity and overall accuracy of CBCT images with all gamma modes (low, medium, and high) were high, and they were slightly higher in the high gamma mode (Sensitivity: 94% and overall accuracy: 100%) than in two gamma modes (low and medium). The sensitivity and specificity of high and medium gamma modes in three regions of the root canal (cervical, middle, and apical) were at optimal thresholds compared to the low gamma mode.

Gamma modes, particularly the high gamma mode, in CBCT imaging can be adopted as a promising processing filter for the detection of internal root resorption.