Fig. 4

Selection of ROI. a T0 selected ROI on the cropped OPG with a size of 30 × 90 pixels on the mesial surface of the implant. b Selected ROI of 30 × 90 pixel size on the distal surface of the implant in the T0 cropped image. c Selected ROI of 30 × 90 pixel size on the mesial surface of the implant in the same location as the T1 image in the T1 cropped image. d ROI selected in the T1 cropped image with a size of 30 × 90 pixels on the distal surface of the implant in the same location as the T1 image