Segmentation of a CT or CBCT scan is the semi-automatic and manual separation and retention of certain tissue types, in our case the bone structures, teeth and dual-scan markers. A qualitative segmentation can only be done if the C(BC)T images are of good quality. Unfortunately, that is not always the case. Compare the red with the green CT scan, both submitted to design an AMSJI. It goes without saying that a good fit depends solely on the scan, on no other factors, as these are checked in the company with Zeiss metrology. An AMSJI that does not fit depends on the quality of the CT, not on the manual adjustment of the segmentation by the engineer...