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Are implants made with a 3D printer good enough?

Quality control of additively manufactured medical products using computed tomography

PTBnews 3.2019
03.06.2019
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additive manufacturing implantology in medicine and dentistry coordinate metrology

Medicine is placing high expectations on implants and auxiliary materials that are manufactured specifically for each individual patient. This can be done by means of additive manufacturing (3D printing), which allows nearly any complex shape to be produced. Before starting to use such implants widely, the medical sector and certification bodies demand proof of the fact that their high quality is matched and will remain stable over time. Within the scope of a European project, MetAMMI, PTB has provided the basis for the quality control of medical implants and auxiliary materials produced by additive manufacturing.

Trial of a dental drilling guide 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

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 inserting 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 shown 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.

Contact

Fabricio Borges de Oliveira
Department 5.3
Coordinate Metrology
Telefon: +49 531 592-5258
Opens window for sending emailfabricio.borges(at)ptb.de