Ultra-Low-Dose versus Normal-Dose Scan Protocol of Planmeca ProMax 3 D Mid CBCT machine in Detection of Second Mesi buccal Root Canal in Maxillary Molars: An ex vivo study

Objective: The aim of this study was to compare the ability of Normal and Ultra-Low-Dose protocols of Planmeca Promax 3 D Mid CBCT unit with different voxel sizes in detection of MB2 canal.
Materials and Methods: This study was conducted on 36 extracted human maxillary first and second molars. Six acrylic models were prepared and six molars were embedded in each model using Inlay wax. Each acrylic model was then placed in a plastic container filled with water. CBCT imaging of the acrylic models containing the extracted molars was taken by Planmeca ProMax 3D Mid machine (Helsinky, Finland). Each model was scanned with three different voxel sizes (0.075, 0.1, 0.2 mm) and two different exposure protocols, namely the Normal-Dose (ND) and the Ultra-Low-Dose (ULD) protocol. Assessment of the number of MB canals was carried out by two Oral and Maxillofacial Radiologists. To verify the number of root canals of the mesiobuccal root, these roots were sectioned and visually inspected. The data obtained were tabulated and subjected to statistical analysis.
Results: Transverse sections showed that 22 molars had two mesiobuccal root canals and 14 molars had only one mesiobuccal root canal. The results showed that the sensitivity and accuracy of CBCT images increase as the voxel size decrease. However, the results revealed no significant difference (p>0.05) between the (ND) and (ULD) protocol of the same voxel size used. Both intra and inter-observer reliability showed very good agreement (0.81–1).
Conclusions: ULD CBCT protocol can be applied for the detection of MB2 of maxillary molars. The smaller the voxel size, the higher the image resolution and image quality. The 0.075 mm voxel size of both protocols is accurate enough to be used as a gold standard in laboratory studies instead of the standard root sectioning technique.