I have a splint for my tmj but fear cancer from grinding and swallowing that plastic at night?

No fear: Plastics are incredibly inert biologically and all the talk about their "causing cancer" is from scaremongers. The artificial chemicals that really cause cancer are the ones that can mutate dna -- a plastic polymer won't even gain entry to a cell. Tmj can be very troublesome and finding an effective treatment difficult -- i wish you luck and admire your courage in writing.

No cancer: I am not aware of any information that links either grinding or ingesting anything from a tooth splint causing cancer. Try to stop grinding and this won't be an issue.

Rare???: Cancer from grinding would be very rare, as far as i know. If the splint is made correctly, it is also unusual for one to break it and swallow the pieces. Anything is possible and that is a good reason not to buy over-the-counter or online mouthpieces. If you have further questions, i would seek out several opinions.

Safe: Same type of plastic used for dentures and partial dentures. Proven safety for decades.

Safe and effective: treatment to protect your teeth. There is no scientific proof that TMJ splint may cause cancer.