Hello, I made an account to post this in the case that anyone else comes across this thread and is considering a mouth guard from Amazon. (I originally chose which mouth guard to try first based on this thread)
I highly recommend not getting one from Armor Guard (linked in an earlier comment). They are publicly rude and unprofessional when confronted with negative feedback in their Amazon reviews. They fought to not let me get a refund. Their instructions are poor relative to similar products. It will also take about a month for you to get a mouth guard from them. Alternative products offer much faster turnaround time, don't make you pay shipping costs, will adjust the guard without cost, and will give full refunds.
I will link my reviews on Amazon for Armor Guard, and for a much better product from JS Dental. The reviews give much more detail if you're interested, and they show that I was a verified purchaser.
Armor Guard:
https://www.amazon.com/gp/customer-reviews/R3B2PG2HSDN5ES?ref=pf_ov_at_pdctrvw_srp
JS Dental:
https://www.amazon.com/gp/customer-reviews/R2VYLRZE16QULG?ref=pf_ov_at_pdctrvw_srp
JS Dental has a more expensive product, but I would say it's worth it without a doubt in comparison to Armor Guard. Their instructions were much better and more professional. I got it within the 7-10 days they quoted after I sent them the mold. It fit well without adjustments, but their free adjustment services alone would be worth the price difference between the products. Unfortunately, this product did not help with my symptoms. I think I experienced something similar to what Bill Bauer did since I seemed to be clenching more after I stopped using the guard. But if you're going to try an Amazon mouth guard, it's a good option.
link to product:
https://www.amazon.com/Dental-Lab-C...0769YSBNX/ref=cm_cr_srp_d_product_top?ie=UTF8
If you have TMJ/TMD, I recommend looking into Urbanek TMJ splints. I was looking into mouth guards primarily for headache problems. I found a local dentist that was able to take a mold and order this specific splint type. I can't speak to the effectiveness of the splint yet. I will try to post an update later whether it helps or not. So far it seems to be helping. I had worse headaches when I stopped using the Amazon mouth guard (which may have been from increased clenching), and I seem to have slightly better headaches with the Urbanek splint. It's hard to tell at the moment how much of that is just day-to-day variation though.
I didn't mean for this to be an ad. I just hope this helps someone else going through a similar process later.