3D Printed Products: What FDA expects you to know
The regulatory classification of your device will most likely be the same regardless of the manufacturing methods, but for 3D printed products (additive manufacturing) FDA stresses the importance of Design Control and therefore, design validation. Some companies who have a Class I device may consider that the quality system regs (21 CFR 820) don’t apply to them but many Class I devices are not “GMP-exempt”. And although Design Controls do not apply to Class I devices, process validation certainly still may [ref 21 CFR 820.70 and .75].
We recommend the use of a process flow chart to identify the steps in manufacturing that may involve the elements of 3D printing. It is particularly important in the flow chart to identify any use of software in the process element. Handing off data from one software system to another is one element of 3D printing where verification or validation may be required. From this flow chart an pFMEA should be derived to assist in the understanding of risks associated with the process step. This risk analysis then can pinpoint the nature of evaluation that may be necessary to assure process performance and a safe device. Even if your product is Class I and exempt from Design Controls, it is prudent to understand that “design requirements drive the processes”.
An example of how a design requirement can drive a process requirement is the tolerance required for certain medical products. For example, if we’re building an oral appliance that must fit around a patient’s teeth, the tolerance of the 3D printer will need to produce a part sufficiently refined to fit around the teeth. Variations of a millimeter could mean the device simply won’t fit. The FDA guidance points out that “pixilation” of features (where an otherwise smooth surface is printed as a series of steps) could be quite uncomfortable in a patient’s mouth. FDA admonishes that for “patient-matched” devices, there should be a “clear understanding of clinically relevant design parameters, the pre-determined range of these parameters, and which parameters can be modified for patient-matching.”
When a medical or dental device incorporates patient imaging data, there are considerations to make, not the least of which is whether the minimum image features (such as image resolution) is adequate. Some software includes a smoothing or image processing algorithm that can alter the output. And manufacturers may need to keep in mind the time elapsed between the image and the manufacturing, since tissues and wound defects can change over time. Understanding the “handoff” (known as file conversion steps) between the image software and the 3D printer is crucial.
Understanding the file format conversion steps will help you plan the level of validation that will be necessary. By defining the crucial dimensions and geometry for your device and understanding how the file conversion might negatively impact the critical attributes and performance criteria will form the basis of the risk analysis and subsequent validation plans. This will also help to anticipate when revalidation may be required if the software versions were to change.
In our next installment we’ll decipher the elements of build preparation software and how it can have an impact on your device qualification.