About FDA´s Technical Considerations for Additive Manufactured Medical Devices

Let´s analyse the FDA´s  Technical Considerations for Additive Manufactured Medical Devices:

• "Final device performance is tied to the material,machine, and post-printing processes. The interaction between the material and machine ...need for a robust process validation and acceptance protocol appropriate to the risk profile of the final device...printing and process parameters should be captured and validated, which can include individual machine validations." (page 3-4)
• "For class II and class III devices and select class I devices, manufacturers must establish and maintain procedures to control the design of the device in order to ensure that specified design requirements are met per 21 CFR 820.30 Design Controls. Manufacturers must also establish and maintain procedures for monitoring and control of process parameters for validated processes to ensure that the specified requirements continue to be met." (page 6)
• "Placement, orientation, and packing density of devices or components within the build volume may be integral to individual device or component quality... Build orientation of each device or component can also impact its functional performance by affecting the anisotropic properties of the device or component. Similarly, many machines have areas of the build volume where they function optimally and areas where they do not. For example, printing may be sub-optimal in the regions near the outer edge of the build volume and optimal at the center. The affected region may be different for every machine, even between machines of the same model." (page 12)
• "The build path, the path traced by the energy or material delivery system (e.g., laser or extruder), can impact the quality of the final finished device or component...it is important to maintain consistency of the build path between identical devices and components... some machines may allow portions of a device or component to have different energy delivery or build path specifications that do not change the geometry of the component or device but may influence the final device performance ... maintaining proper calibration and performing preventative maintenance have been identified as key factors to achieve low rejection rates of devices and components from an individual machine ... optimal settings and parameters for a single model of a machine can vary greatly when printing different devices or components. Furthermore, optimal settings and parameters can vary between machines of the same model even when printing the same devices or components". (page 14) 
• FDA considers photopolymer 3D resins as starting raw materials used for making medical devices, but not as medical device as supplied: "the starting material may undergo significant physical and/or chemical changes. As such, the starting material can have a significant effect on the success of the build cycle, as well as on the properties of the final finished device." (page 15)
• The specifications of the incoming materials (e.g., powders, liquid monomer/polymer systems) may be different from the properties of the finished devices... when any material specification is changed, the effect on the build process and the final device should be well-understood and documented." (page 16)
• "Final device performance and material properties can be affected by post-processing steps of AM (i.e., manufacturing steps occurring after the printing process). These steps could include removing manufacturing residues from the device, heat treatments of the device to relieve residual stress, and final machining. All post-processing steps should be documented and include a discussion of the effects of post-processing on the materials used and the final device. As stated previously, manufacturers must establish and maintain procedures for monitoring and control of process parameters for validated processes to ensure that the specified requirements continue to be met." (page 17)
• "Validation of medical devices and their manufacturiong process needs to be performed by medical device manufacturers" (page 18)
• "Mechanical properties of the device may be impacted by orientation and location, it is important to ensure that production processes are properly developed, conducted, controlled, and monitored in order to ensure that devices or components are not adversely affected by fabrication orientation." (page 23) 
• "For AM processes that use polymer crosslinking, the percent crosslinking and degree of curing should be evaluated to ensure that the AM process results in a material that is fully cured and within specifications." (page 25)
• "Manufacturing material means any material or substance used in or used to facilitate the manufacturing process, a concomitant constituent, or a byproduct constituent produced during the manufacturing process, which is present in or on the final finished device as a residue or impurity not by design or intent of the manufacturer. There is also an increased risk of residual manufacturing material, such as excess starting material or support material, remaining on the final finished device. Since residual manufacturing material may negatively affect the performance of the device, you should describe the process used to ensure removal of residual manufacturing materials to a level where they do not affect the safety and effectiveness of the device." (page 26)
• "When a manufacturing material could reasonably be expected to have an adverse effect on device quality, the manufacturer must establish and maintain procedures for the use and removal of such residual manufacturing material to ensure that it is removed or limited to an amount that does not adversely affect the device's quality... Therefore, only devices that are sufficiently cleaned of residual manufacturing materials should be provided to the end user." (page 26)

Conclusions

The FDA clears or approves finished medical devices, not specific materials , nor their raw materials, for general use in the manufacture of medical devices, including materials that may be used in the manufacture of 3D printed devices.

Materials used in formulating or constructing medical products are evaluated within the context of FDA’s evaluation of the safety and effectiveness of the medical product for its intended use.

Like devices made using other manufacturing processes, devices made using 3D printing technology are subject to regulatory requirements. Fulfilling Quality System (QS) requirements for a device is determined by its regulatory classification or regulation to which it is subject, if applicable. 

Medical devices are classified into Class I, II, and III. Regulatory control increases from Class I to Class III. The device classification regulation defines the regulatory requirements for a general device type.