Quality control of additively manufactured medical products using industrial computed tomography

To find out how reliable medical implants and auxiliary materials from a 3D printer really are, numerous specimens (implants, medical guides and regular-geometry objects) were produced within the scope of the project. In this context, various materials and techniques of additive manufacturing were used. The examination focused, in particular, on those characteristics that may be relevant for the function of a given implant such as its shape, surface, density and mechanical properties. To this end, different measurement methods were used (use of Archimedes' principle, coordinate metrology, computed tomography with X-rays and THz radiation). It turned out that the quality of an implant depends, in particular, on the material and on the manufacturing technique used.

Practical cases from everyday work in hospitals were also investigated within the scope of the project. One of these investigations dealt with drilling when implanting dental implants. In such surgical interventions, it is important to prevent adjacent dental roots or nervous tissue located in the lower part of the jaw from being damaged. The drilling angle and the drilling depth must therefore be checked very accurately. In order to ensure stable and accurate drilling, dental drilling guides are used.

In cooperation with a dental surgery, medical physicists and dental technicians, several dental drilling guides produced by additive manufacturing were used to drill holes for implants into lifelike artificial jaw models. Subsequently, the drilling depth and the drilling angle were determined by means of industrial computed tomography. The results have showed that the drilling depth differed by less than 2 mm, and the drilling angles by less than 6°. If the deviations are kept that small, no physical damage to the patient is to be expected.


Fig. 1: Trial of a dental drilling guides produced by additive manufacturing for the drilling of holes to fit dental implants into artificial jaw models with only few abutment teeth. The drilling angle α and the drilling depth were measured by means of computed tomography.