3D resins are raw materials, not finished medical devices

Biomedical or food packaging certifications of photoreactive liquid photopolymers or 3D resins considering them as medical devices, or food grade packaging are non valid, non relevant, are misleading, do not make any sense, nor provide any warranty, nor safety, nor biocompatibility assurance for final medical device users, since most photopolymer 3D resins are cytotoxic before and even after printing unless they are custom designed in tune with appropriate printing and processing workflows to ensure their full cure, cleansing and safety. Biomedical device (and food packaging) manufacturers need to design high quality medical devices with compliant raw materials "3D resins", workflows, processes and protocols  to achieve the required biocompatibility for each class of biomedical device or food packaging system. Photopolymer 3D resins are liquid photo reactive raw materials, which photopolymerise or react with light in the printers, normally layer by layer, to cure or become printed solid materials with a specific shape. They need to be designed properly with safe non leachable / extractable ingredients after postcuring and postprocessing to ensure that they are fully cured and free of leachable / extractable contaminants, unreacted monomers, residuals and reaction byproducts.

Toxicity of biocompatible 3D resins before & after printing

Discover these recent published findings about the toxicity of Formlabs Dental 3D resins even after printing and postprocessing: 

Fig. 2

As clearly highlighted in the mentioned scientific paper published by the Northwestern University (Chicago, USA), Formlabs’ Dental SG and LT Clear printed in Form 2 SLA 3D printer were toxic, despite being certified as biomedical devices. Similarly, the resin of Graphy for direct printing of aligners also may raise concerns on potential health hazards as reported in this paper published in the European Journal of Orthodontics: Leaching from a 3D-printed aligner

"Although efficiently polymerized and BPA free, the great variability in the amount of UDMA monomer leached from the examined samples may raise concerns on potential health hazards after repeated intraoral exposure"

Reasons for biocompatibility failure

Biocompatibility and safety failure can be due to an inadequate resin design from its conception, and/or due to an inadequate postcuring and postprocessing, leaving the aligner full of soluble leachables and extractables, unreacted monomers, residuals and reaction byproducts. 

3Dresyns statement: "3D resin suppliers cannot ensure, nor grant  any warranty, as a blank cheque, of certifiability since the quality and safety of any manufactured biomedical device it is beyond its competence and control. Nevertheless, 3D resin manufacturers are responsible of making resins compliant with the quality requirements of the claimed standards, for aiding manufacturers in getting the required certifications for making biomedical devices"

Analysis and split of 3D resin and medical device manufacturer responsibilities for biocompatibility:

  • 3D resin suppliers are responsible for designing and producing resins compliant and in accordance to the applicable regulations for which they have been designed:
    • 3D resins need to be designed with safe non leachable biocompatible ingredients, after appropriate curing, printing, postcuring and postprocessing, to avoid the risk of causing cytotoxicity and potential health hazards
    • 3D resin suppliers cannot be liable nor responsible for leachables and extractables when inappropriate curing, printing, postcuring and postprocessing protocols and controls are used by medical device manufacturers in their premises and under their resposibility as final manufacturers
  • Medical device suppliers are responsible for designing and producing medical devices compliant and in accordance to the applicable regulations for which they have or should have obtained the certification (for producing the specific sort and class of the produced medical devices):
    • medical devices need to be designed with safe non leachable biocompatible raw materials "resins", after appropriate curing, printing, postcuring and postprocessing, to avoid the risk of causing cytotoxicity and potential health hazards
  • Medical device manufacturers are responsible for:
    • the appropriateness of the chosen resin, printer, post processing equipment, quality control* instrumentation, and their implementation and protocolization in their production workflow for ensuring the production of safe biocompatible medical devices
    • the final quality, including the overall performance and safety of their produced and traded medical devices, and compliancy with the relevant and applicable regulatory standards
*Note: quality control by the device manufacturer should include the analysis, elimination and control of any potential leachables and extractables during use by final customers, which depend on the polymer conversion (which depends on printer, printing and postcuring specifications), the type (their solubility and potential toxicity) and concentration of raw material residuals, byproducts, impurities, and contaminants, as well as their elimination, extraction and sterilization before commercialization, etc.  

    Conclusions

    • Non-properly designed and produced biocompatible resins, despite undertaking appropriate cleaning, postcuring and postprocessing fail the biocompatibility testing
    • Properly designed and produced biocompatible resins with the appropriate cleaning, postcuring and postprocessing pass the biocompatibility testing, but may also fail with inappropriate cleaning, postcuring, postprocessing, and controlling of the safety and quality of medical devices
    • Medical device manufacturers are responsible for implementing the right printing, cleaning, postcuring, postprocessing protocols, and quality controls in clean room production facilities to ensure maximum safety of their products

    Learn more about biocompatibility of 3D resins: