Reconsideration of the horizontal tube-shifting technique in the intraoral radiography of maxillary molars.

Objective: The horizontal tube-shifting technique can be adopted to separate overlapping buccal roots of the maxillary molar from the palatal root. A simulation study was performed to determine an appropriate tube-shift angulation when adopting three-dimensional computed tomography imaging.

Methods: Cone-beam computed tomography images of 21 volunteers were used for simulation. Adopting image analysis software, maximum intensity projection (MIP) three-dimensional images of maxillary molars observed from directions similar to the direction of an intraoral radiography X-ray beam were reconstructed. The orthoradial projection angle was taken as the baseline and the tube-shifting technique was then simulated to separate superimposed buccal roots from the palatal root.

Results and conclusion: The tube-shift technique was considered applicable to maxillary molars for 29/42 teeth (69%) in the case of a mesial tube shift and 40/42 teeth (95.2%) in the case of a distal tube shift. The specific shifting angle suitable for observing the buccal root apex of the maxillary molar without overlapping was obtained.