What is a medical device?

The FDA defines a medical device as an article intended for diagnosis, cure, mitigation, treatment or prevention of disease, or to affect the structure or function of the body, without achieving its primary purpose through chemical action and without being metabolized to achieve that purpose.

FDA reference definition

• What is a medical device? (FDA definition reference)

Why a 3D resin is not a medical device as supplied

A 3D resin is a starting raw material that can be used to manufacture medical devices, but it is not a medical device “as supplied”. In photopolymer additive manufacturing, the starting material can undergo significant physical (liquid → solid) and chemical (photopolymerization) changes, and these changes directly influence the final part.

FDA: additive manufacturing is a material–process–device system

FDA highlights that:

• Starting materials change during manufacturing and can significantly affect build success and final device properties (see FDA guidance, page 15).
• Post-processing affects performance and must be documented, with monitoring and control of validated process parameters (page 17).
• Material identification and control matter: source, purity, and documentation (e.g., CoA / MSDS) support review (page 24).
• Degree of cure must be evaluated for polymer crosslinking processes to confirm the material is fully cured and within specifications (page 25).
• Residues must be reduced/controlled to levels that do not adversely affect quality or safety, including worst-case geometry conditions (page 26).

Reference document:

• FDA: Technical Considerations for Additive Manufactured Medical Devices

European Commission perspective

In the EU framework, regulatory obligations apply to the medical device placed on the market (and the responsible manufacturer), not to its constituents or raw materials. 3D printed parts may be used to produce medical devices, and manufacturers must ensure compliance with the applicable legislation, including conformity assessment, technical documentation, declaration of conformity and CE marking.

Key EU references

• Directive 93/42/EEC (Medical Devices Directive, MDD)
• Conformity assessment procedures for 3D printing and 3D printed products used in a medical context (European Commission, COVID-19 guidance)

From MDD to MDR

With effect from 26 May 2021, Regulation (EU) 2017/745 (MDR) replaced Council Directive 90/385/EEC (active implantable medical devices) and Council Directive 93/42/EEC (medical devices). The core principles remain, and the MDR expands requirements and clarity for many areas.

• Regulation (EU) 2017/745 (MDR)
• Council Directive 90/385/EEC (Active implantable medical devices)
• Council Directive 93/42/EEC (Medical devices)

Conclusions

Photopolymer 3D resins are photo-reactive starting materials, not finished medical devices. Because they undergo physical and chemical transformation during printing and post-processing, the final safety and performance of a printed medical device depend on the validated workflow used by the device manufacturer (printer + parameters + cleaning + post-curing + post-processing + quality controls).

To manufacture safe devices, the overall workflow specifications and controls must be designed, implemented and verified to ensure consistent quality, performance and biocompatibility for the intended use.