**4.3. Precision attachment design**

Often facial prostheses are retained using precision attachments including osseointegrated implant retained magnets, bars and clips. In these situations, external markers, or bosses, are

**Figure 4.** (a) Images illustrating the use of external markers, or bosses, to detail the position of precision attachments to aid retention of the prosthesis. (b) Translation of the geometric position of the attachment points for the precision at‐ tachments within the prosthesis (Approx. part Dim: 40 × 24 × 25 mm). (c) Checking of CAD design to check no interfer‐ ence of surface geometry caused by incorporation of precision attachments.

used to identify the position, angulation and orientation of any attachments that need to be incorporated into the data incorporated in to the process. Their position can then be translated through the design and manufacturing process into the final prosthesis (**Figure 4**).
