Fig. 2

IRD measuring technique on PAN (a) and CBCT (b) with overlapping structures in PAN. a Outer surfaces of implant and neighboring root (dotted white line) are assessed on PAN images. At the area of smallest distance, i.e. greatest overlapping distance, between implant and adjacent root surface the local implant thread was used as reference point for IRD measurement (red line). b Outer surfaces of neighboring implant and root were assessed at the level of the reference thread on axial CBCT images. IRD represents distance between implant and adjacent root surface at the level of the reference thread (red line)