[rl3]

Not to be a downer, but was any thought given to the safety of the plastic(s) used?

This is something that's in your mouth a lot and constantly exposed to saliva.

The Dimension 1200es mentioned doesn't appear to be specific to medical applications.[0] The product page lists the only compatible thermoplastic being ABSplus-P430. The MSDS for that basically says the stuff is dangerous in molten form, and beyond that there's very little data.[1] The same company makes "Dental and Bio-Compatible" materials for use with their other products, and these appear to have considerably more safety data.[2]

>The aligner steps have been printed, in addition to a “riser” that I added in order to make sure the vacuum forming plastic (sourced from ebay) ...

As another commenter pointed out, the vacuum forming plastic is probably the primary concern because the 3D printer was just used to create the molds. The specific type of vacuum plastic isn't mentioned.

Regardless, very neat project.

[0] http://www.stratasys.com/3d-printers/design-series/dimension...

[1] http://www.stratasys.com/~/media/Main/Files/SDS/P430_ABS_M30...

[2] http://www.stratasys.com/materials/material-safety-data-shee...

[dezork]

I used Keystone PROFORM .030" Retainer Material. Keystone is a dental supplier, so I trust the plastic is biologically inert.

[amelius]

This whole issue should be mentioned in the article, just in case anybody ignorant wants to do this with unsuitable materials.

[dezork]

Good point. I'll add some info about this.

[rl3]

Nice. The only other risk then would be interaction or contamination between the retainer material and the printed mold during the forming process (high heat), but that's probably grasping at straws.

The SDS for the retainer material in case anyone's interested:

http://dental.keystoneindustries.com/wp-content/uploads/2016...

The toxicology section is entirely devoid of data, but I doubt that means anything since the product is purpose-built for dental use in the first place. Safety Data Sheets are more oriented towards immediate and occupational hazards anyways.

[justinclift]

Taulman Nylon 680 FDA would probably be suitable too, for anyone using a more generic 3D printer. :)

[johnloeber]

This is a great point to raise. OP, please make sure that both the plastic you used, and the chemicals released as saliva gradually breaks down the plastic, are not going to be harmful. You wouldn't want long-term exposure of your gums to harmful agents. But that's probably the only concern.

Regardless: great job. I'm very impressed by this project -- I love seeing applications of 3d printing. Especially one like this turns an expensive (and slow!) medical procedure into something that can be done easily at home, or cheaply in the office of a trained professional.

[additively]

> I love seeing applications of 3d printing.

So do we over at Additively (your post made me signup after just reading HN for a while). We publish showcases such as the commercial application of the posted aligners on our site - more curated showcases will be published soon.

https://www.additively.com/en/showcase

Edit: That's the commercial 3d printing use case mentioned (Invisalign isn't the only one):

https://www.additively.com/en/showcase/en/steiner-werkzeugma...

[snarfy]

The plastic used in real Invisalign is HDPE, the same stuff used in plastic water bottles. It can be 3d printed. Real Invisaligns are 3d printed with HDPE (I was a patient).

[Vexs]

Hm, It's not really being too heavily "interfaced" with the body. I wouldn't stick it under your skin, but this would probably be fine I think. I'd also think that most things are unsafe in molten form, heh.

[Fomite]

If it's friendly toward bacterial growth, you might not want it near your gumline. Oral infections can get nasty fast.

[Eduard]

Rubbing drugs on gums is a popular way of administration, as the substances get easily absorbed into blood vessels here.

[pyre]

Well, people put BPA in plastics even though it was known to be toxic because the thought was that the material would bind the BPA in place (i.e. it would always stay in the material).