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Objectives To predict temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDWR) from condylar shape, position, and dimensions obtained from CBCT images. Methods This cross-sectional study was performed on 17 patients suffering from temporomandibular disorders diagnosed by history taking according to the chart of the American Association of orthodontists, clinical examination according to the Helkimo index and MRI. CBCT and MRI examinations were performed within one-week interval. Disc position, diagnosed by MRI was used as the gold standard. TMJs with posterior disc displacement or anterior disc displacement without reduction were excluded. Qualitative and quantitative analyses were performed on CBCT images to find the correlation between condylar variables and ADDWR. A logistic regression model was created to estimate ADDWR from condylar dimensions (height, width and depth). Results Condylar shape and condylar position in the glenoid fossa were significantly correlated with ADDWR (P < 0.05). Condylar width, height and depth were significantly smaller in condyles with ADDWR compared to condylar dimensions in normal disc position. Logistic regression analysis could be used to predict the probability of anterior disc displacement with reduction from condylar dimensions. Conclusion Condylar shape, position, and dimensions assessed by CBCT are significantly correlated with ADDWR of the TMJ. Substituting the values of condylar width, height and depth in the equation suggests the probability of ADDWR.

Objectives To compare the difference in mandibular canal (MC) visibility using three different cone beam computed tomography (CBCT) acquisition protocols: high resolution (HR), standard resolution (ST) and Quick scan+ (QS+). Methods Twenty-five human dry mandibles were scanned by one CBCT machine; i-CAT FLX (Imaging Sciences International, Hatfield, PA, USA), using three different acquisition protocols: high-resolution (HR), standard (ST) and Quick scan+ (QS+). DICOM data were transferred to a third party software Ondemand 3D (Cybermed Co., Seoul, Korea). The fusion module was used to superimpose images derived from different acquisition protocols to standardize the areas to compare the MC visibility. Comparison was performed at nine selected cross sections extending from an area distal to the third molar posteriorly to the first premolar anteriorly. Two expert radiologists evaluated the degree of MC visibility using five-scale scoring system. Results There was a statistically significant difference between the three acquisition protocols (HR, ST, QS+) at all investigated areas regardless of dentition status (p value < 0.001-0.034) except at the MR1M area where there was no statistically significant difference (p value = 0.094). HR protocol showed the highest prevalence of fully and partially corticated MC at almost all investigated areas while QS+ protocol showed the highest prevalence of invisible MC and clear and unclear noncorticated MC at almost all investigated areas. Conclusions QS+ protocol of i-CAT FLX CBCT machine is a recommended low-dose CBCT acquisition protocol for MC visibility at dentulous posterior mandibular regions while ST protocol is recommended at edentulous areas.