The printing and production of biocompatible medical and dental devices with 3D printed resins require appropriate experticise, equipment, and quality control assurance, including appropriate sofware, printers, printing, and post processing and quality control equipment, including properly designed and implemented biocompatible manufacturing protocols and workflows.
Ideally, liquid 3D resins need to be designed and tuned in accordance with appropriate printing and post processing units, protocols, and workflows for achieving maximum biocompatibility.
- Constant power printers and light boxes without suffering from light power decay upon usage are needed to ensure and warranty the quality and safety of 3D printed biomedical devices:
- printers and light boxes with too low light and variable power can yield to low polymer conversions leaving excessive unreacted monomers and extractables due to undercuring, which compromise safety and biocompatibility since free unreacted monomers, leachables, and extractables can leach out and be extracted during usage
- 3D printed biomedical devices need to be fully cured and free of extractables before commercialization and usage since residual leachables and extractables can be extracted, eg by the saliva of the mouth in dental and orthodontic applications
- Extractables can have a bitter taste and cause irritation and other potential hazards, which depend on the hazards of the chosen liquid resin as supplied. Read the MSDS of the 3D resin to identify the health hazards of the liquid 3D resin as supplied to identify the potential risks and hazards for users unless full curing and cleansing is ensured before usage
- a thermal oven (optional, needed in method 2 is used)
- quality control instrumentation to ensure that biomedical devices comply with the relevant quality and safety specifications
Cleaning and post processing biocompatible protocols
The Instructions for Use IFU for ultra gloss and transparency can be used for printing and post processing clear and colored prints for medical applications. Opaque colored prints exhibit light postcuring limitations since light cannot penetrate the prints. Consequently, thermal cleansing, ideally by dipping prints, firstly in Cleaning Fluid UNW2 Bio and secondly in water, is required to increase monomer to polymer conversion and eliminate extractables and leachables.
The optimum time and system for fully curing the resin needs to be determined by experimentation since depends on many variables beyond our control, such as the printer, printing, and light box specifications and settings, light power, wavelength, exposure times, total energy dosage, etc.
Attention needs to be drawn to monitor and prevent the light power decay upon usage of printers and light boxes to prevent excessive and uncontrolled quantities of uncured monomers trapped in the medical devices.
When instructions are followed without cutting corners prints with excellent gloss, transparency, surface quality, light fastness, mechanical strength, and safety can be successfully made. The cleansing yield depends on the cleaning time and chosen temperature. The higher the temperature the shorter the time needed for fully cleansing the prints. Some 3D resins have been designed to withstand high temperature (eg boiling water / 100ºC) without mechanical degradation and yellowing. At the boiling temperature of water or higher the cleansing yield is increased resulting in increased polymer conversion and removal of extractables, leachables, contaminants, and byproducts.
Some 3D resins can suffer a significant decrease of mechanical strength when boiled in water. In these cases, use lower temperatures (eg 60~70ºC and longer cleaning time to prevent any potential decrease of mechanical strength. Excessive temperature and time of dipped prints in water or in Cleaning Fluid UNW2 Bio can decrease the gloss and clarity of some 3D printed resins.
Biocompatible prints will not be ready for use until maximum polymer conversion and full cleansing are achieved. Biocompatible prints should be free of extractables and leachables. The safety and biocompatibility of prints are responsibility of medical device manufacturers since their quality and safety depend on the design, implementation, quality assurance and "in house" production of their products with the right printing and post processing protocols and controls.
3D resins as supplied are liquid photoreactive systems, which can be compliant after proper printing and post processing, but not certified as pretending to be medical devices, since 3D resins are raw materials, not printed medical devices.
Depending on how medical devices are printed and post processed they may end up being safe or not. Full elimination of unreacted monomers, leachables, and extractables needs to be ensured by medical and dental device manufacturers before commercialization for preventing any potential health hazards and ensuring maximum safety for final consumers.
3D printed medical devices fall within the scope of specific EU product legislation, such as the EU Medical Device Regulation MDR 2017/745. Therefore, manufacturers of medical devices must ensure that their 3D printed products meet the requirements of the applicable EU legislation, carry out the necessary conformity assessment procedures, compose a technical file, draft the EU declaration of conformity and affix the CE marking, before placing them on the EU market.
3Dresyns can help you to choose (and if needed to design) compliant 3D resins and certified production workflows to meet the final specifications and requirements of your in house printed and produced biomedical devices, including dental, orthodontic, and implant devices.
3Dresyns offers consulting services to help medical device manufacturers to design and implement appropriate protocols and workflows to manufacture biomedical devices compliant and certifiable by the relevant applicable regulations (FDA and ISO, class I, II, III, IV, etc). For more info read:
For more info about biocompatible 3D printed resins read:
- About Certification of biomedical devices and food packaging
- What is a medical device?
- 3D resins are raw materials, not finished medical devices
- Safety Benefits of our 3Dresyns
- Responsibilities of manufacturers of 3D resins for medical uses
- About the importance of tuning 3D resins in accordance with appropriate printing and postprocessing units/protocols for maximum biocompatibility
- Effect of printing specifications on biocompatibility and mechanical properties
- Effect of fine tuning on biocompatibility and mechanical properties
- Effect of printers on biocompatibility, safety and mechanical properties
- Key variables affecting mechanical performance of 3D prints
- Tg, HDT, and mechanical properties depend on printing specifications
Learn more about Sterilization of 3D printed resins for medical devices