Testing of biocompatible 3D printed resins

Our 3D resins for dental, orthodontic and biocompatible medical applications have been designed to comply with the applicable Standards for which they have been intended, after appropriate tuning, printing and post processing with the right equipment and quality control instrumentation, protocols, and workflows.

Tuning refers to the required adjustment of the 3D resin with tuning addtives, such as photocatalysts and resolutioners (as well as with colors and functional additives), to the chosen printer and post processing equipment by the medical device manufacurer, which determine the dosages and types of tuning additives and their effect on the final biocompatibility of 3D printed medical devices. 

Our 3D resins are tuned to different printer specifications to facilitate their printability with the different printer specificatons. Nevertheless, their biocompatibility cannot be ensured, nor granted as a blank cheque since the biocompatibility of any 3D printed biomedical device depends on the whole 3D printing and postprocessing system, not on the 3D resin as supplied. 3D resins are raw materials, not medical devices. which depending on their tuning, printing and post processing equipment and manufacturing may pass or fail the different biocompatibility testing. Not all printers and post processing equipment meet the minimum quality requirements for printing biocompatible 3D resins.

3D resin manufacturers are responsible for making resins as biosafe as possible and compliant with the quality requirements for their intended use, for aiding medical device manufacturers in passing the relevant ISO testing standards and in getting the required certifications for making high quality biomedical devices with appropriate printers and post processing equipment and good manufacturing practices.

The applicable ISO testing standards are used for measuring extractables & leachables for 3D printed medical devices with photopolymer resins are ISO 10993-17 and ISO 10993-18, while USP 661 is used for plastic packaging systems( pharmaceuticals, biologics, dietary supplements, and devices) and their materials of construction. 

The following testing standards are used for testing the overall biocompatibility of 3D printed medical devices with photopolymer 3D resins and with other 3D printing materials:

ISO 13485:2016 Medical devices. Quality management systems. Requirements for regulatory purposes
ISO 20795-1:2013 Dentistry. Base polymers:
  • Ultimate flexural strength ISO 20795-1
  • Young´s or Flexural modulus ISO 20795-1
  • Sorption  ISO 20795-1
  • Solubility ISO 20795-1
  • Residual monomer ISO 20795-1
    • ISO 10993-1: 2018 Biological evaluation of medical devices. Part 1: Evaluation and testing within a risk management process
  • Biocompatibility: cytotoxicity ISO 10993-1
  • Biocompatibility: mutagenicity ISO 10993-1
  • Biocompatibility: erythema or edema reactions ISO 10993-1
  • Biocompatibility: sensitizer ISO 10993-1
  • Biocompatibility: systemic toxicity ISO 10993-1

    • ISO 10993-2:2006, Biological evaluation of medical devices — Part 2: Animal welfare requirements
    ISO 10993-3, Biological evaluation of medical devices — Part 3: Tests for genotoxicity, carcinogenicity and reproductive toxicity
    ISO 10993-4, Biological evaluation of medical devices — Part 4: Selection of tests for interactions with blood
    ISO 10993-5, Biological evaluation of medical devices — Part 5: Tests for in vitro cytotoxicity
    ISO 10993-6, Biological evaluation of medical devices — Part 6: Tests for local effects after implantation
    ISO 10993-7, Biological evaluation of medical devices — Part 7: Ethylene oxide sterilization residuals
    ISO 10993-9, Biological evaluation of medical devices — Part 9: Framework for identification and quantification of potential degradation products
    ISO 10993-10, Biological evaluation of medical devices — Part 10: Tests for irritation and skin sensitization
    ISO 10993-11:2017, Biological evaluation of medical devices — Part 11: Tests for systemic toxicity
    ISO 10993-12, Biological evaluation of medical devices — Part 12: Sample preparation and reference materials
    ISO 10993-13, Biological evaluation of medical devices — Part 13: Identification and quantification of degradation products from polymeric medical devices
    ISO 10993-14, Biological evaluation of medical devices — Part 14: Identification and quantification of degradation products from ceramics
    ISO 10993-15, Biological evaluation of medical devices — Part 15: Identification and quantification of degradation products from metals and alloys
    ISO 10993-16, Biological evaluation of medical devices — Part 16: Toxicokinetic study design for degradation products and leachables
    ISO 10993-17, Biological evaluation of medical devices — Part 17: Establishment of allowable limits for leachable substances
    ISO 10993-18, Biological evaluation of medical devices — Part 18: Chemical characterization of materials
    ISO/TS 10993-19: Part 19: Physico-chemical, morphological and topographical characterization of materials.
    ISO/TS 10993-20: Biological evaluation of medical devices — Part 20: Principles and methods for immunotoxicology testing of medical devices
    ISO/TR 10993-22:2017: Biological evaluation of medical devices — Part 22: Guidance on nanomaterials
    ISO 10993-23: Biological evaluation of medical devices — Part 23: Tests for irritation
    ISO 14971:2007, Medical devices — Application of risk management to medical devices

    Medical device classification (source EU UDI Helpdesk): 

    "Medical devices are classified into four risk groups, according to the classification rules: I, IIa, IIb, and III (depending on the risk during use).In Annex IX of EU Directive 93/42/EEC, the classification principles are laid down in great detail. The manufacturer is responsible for applying the classification rules, which are determined by the products' intended intent.

    1. Class I Devices: Low risk, non-invasive, everyday devices or appliances are classified as class I devices. The manufacturer is required to complete technical file for such devices.Fact sheet on class I devices
      1. Class Is Devices: Class Is devices are comparable to class I devices. Additionally, they include sterile devices in this sub-group. These devices also require a technical file, as well as an application to a European Notified Body for manufacturing certification in accordance with sterility requirements.
      2. Class Im Devices: Similar low-risk measuring devices. The manufacturer must provide a technical file and be certified by a European Notified Body for manufacturing in accordance with metrology regulations.
    2. Class IIa Devices: Class IIa devices generally include low to medium risk and refer mainly to devices installed within the body in the short term. Class IIa devices are those which are installed within the body for only between 60 minutes and 30 days. Requirements are technical files and a conformity test carried out by a European Notified Body.
    3. Class IIb Devices: Slightly more complex than class IIa devices, class IIb devices are generally medium to high risk and will often be devices installed within the body for periods of 30 days or longer. Identical compliance route to class IIa devices with an added requirement of a device type examination by a Notified Body.
    4. Class III Devices: Class III devices are strictly high risk devices. The steps to approval here include a full quality assurance system audit, along with examination of both the device’s design and the device itself by a European Notified Body."
    For more info read: MDCG 2021-24 Guidance on classification of medical devices

    Related 3Dresyns web documents: