Sterilization of printed parts


#1

I’d like to use some of the parts I’ve been printing in an operating room, meaning they need to be sterilized. I know certain FDM materials can be sterilized, does anybody have any experience or insight about the FormLabs resin and it’s properties relating to this?

Thanks in advance


#2

Aside from the mystery oils in the resin, these parts are quite sharp when they unexpectedly break. Maybe consider using castable resin and going to real metal?


#3

Believe it or not, I have the same question for OR use. Let me know if you get any info. My assumption based on material information that I can find so far is that this is some type of acrylic.


#4

OK. Medical plastics designer here. You have several things to think about.
Putting aside the biocompatability issues, and assuming it is not coming in contact with a patient, because these resins are not good for this. There are far too many residuals of the photo initiator left in the resin to pass any cycotoxicity test.

For sterilization there are several methods. The most common are:

  1. Steam autoclave normally 137degree high pressure steam. You might get your part to survive it once, and you will need to allow plenty of time for it to normalise afterwards because the resin is hydrophillic and will take on the water in these conditions. This will make the resin go like toffee/caramel and distort, but it will re harden, if you can keep in in the right shape.
  2. Ethylene Oxide. This will be no problem for the resin to survive, but you will need to be concerned about residuals. These are the potentially harmful chemical by products of the EtO that are left deep inside the plastics. Again one cycle is probably fine. Most plastics are limited to two cycles in their lifetime before the residuals are considered too high.
  3. Gamma radiation. This will destroy the polymer cross-linking in your resin, resulting ultimately in dust. Most suited to metal instruments.
  4. Cold gas plasma. This is the most recent and most appropriate if you can get access. It is a surface based treatment, so you have to be careful that all surfaces are exposed, but it does very little damage and is cheap. It is less widely available however.

Hope this helps.
Andrew


#5

Appreciate the detailed response Andrew. Prints themselves will not touch the patient but tools that touch the prints may then get used to implant. Most of our sites have access to plasma but they require a manual or validated process to sterilize specific materials. Unfortunately I don’t have the resources right now to go through and test/validate a procedure for this resin.

Hopefully somebody with the resources (FormLabs? :wink: ) will see the potential for this type of application and create support for it!


#6

Has anyone had any luck regarding sterilizing the clear resin? I have a model I want to take to the OR next week and am looking into EtO and H2O2 sterilization as options. While the new dental resin would be ideal, the non-transparent finish makes this suboptimal.


#7

EtO is the big question for the dental resin (which I’ve asked. I can guarantee you that anything with a water (steam or H2O2) will absorb into the acrylic. It is very hygrophylic! But if it’s a single exposure, and does not have high dimensional tolerences… you may be fine with it.


#8

Dental is definitely designed to be sterilized.

Why is a transparent finish important for your application?


#9

We are printing hollow vascular models to allow catheters, guidewires and stents to be placed inside and still be visible.


#10

If they are just used as models, why do they need to be sterilized?


#11

We would like to be able to handle the models while scrubbed in a case to guide what we do.


#12

Does anyone have a definite answer for this then?
We too are currently considering printing a part which will have to be sterilized with an autoclave,
but we’re uncertain if any of the resins available can withstand the process multiple times.
Would the dental resin do the trick?


#13

Reviving this thread as I am curious if there is any new information.
Can any resins be sterilized using peroxide based systems?


#14

Check out the Formlabs Dental SG resin. It is designed to survive the autoclave sterilization process and is biocompatible. Be sure to check exactly what you need for biocompatibility - their master file includes testing for cytotoxicity, genotoxicity, systemic toxicity, sensitization and irritation.

I would not use a peroxide based sterilization process on any of these materials. I don’t know if Formlabs has run any testing for that, but I can’t imagine there wouldn’t be a lot of residuals hanging around.


#15

I’m going to be putting water through a device I’ve made over a long period of time. I will not be able to dry the parts between tests. Would Dental SG be the best bet if all of the others are hydrophylic? Or are there other options? Tough or Durable?


#16

I have an interest in working with a printed part that needs to be sterilized several times. How many autoclave cycles would a part resist? It seems like the clear resin would only resist one or two cycles. How about the dental SG resin? How many times can I autoclave it?
Thank you!