Table 1 Evaluation items selected for STL image quality evaluation

Critical anatomical reference point (CARP)

For the evaluation of the image quality of an STL, specific cranial anatomical landmarks were necessary. The purpose of these anatomical landmarks was to make it possible to differentiate between different levels of STL image quality. For example, the different degrees of clarity of the delineation of the orbital foramina and the mandibular canal could be used as a means to evaluate STL image quality.

Ring artifact

For the evaluation of the image quality of an STL, the presence or absence of a ring artifact could be used as an evaluation item of image quality. The presence of these concentric rings could hamper the design process and be indicative of reduced STL image quality.

Overall impression of STL

For the evaluation of the image quality of an STL, the overall impression of the designers who used the STL for prosthesis design, could be indicative of STL image quality. Their experience on the ease of use of an STL in the design of the prosthesis could make a valuable contribution to the evaluation of STL image quality.

Composite evaluation item(s) that include all CARP measurements

For the evaluation of the image quality of an STL, a composite measurement (description) may be an advantage because the sum of all the CARP measurements could be a more comprehensive measurement (description) of STL image quality.

Composite evaluation item(s) that include all CARP measurements and presence or absence of ring artifact measurement

For the evaluation of image quality of an STL, a composite measurement (description), which includes the presence or absence of ring artifact, may be an advantage because the sum of all these measurements could be a more comprehensive measurement (description) of STL image quality.