I started grinding my teeth after having a child, because children do that to you.
I tried a few "custom fit" dental guards from Amazon and came close to liking none. They all shrank and shriveled up to something that lacked any credibility. The dentek one that came with a tray was almost there, but the tray was one-size-fit-all and I felt like my mouth was a bit wider than the tray, because the end result felt very pinch-y once I tried it on for the night.
So I thought I would give this one a try, and I've been wearing it for a month straight now.
It doesn't require molding or boiling and is not very intrusive. The adjustment on one side of mine broke after the first night, which meant it would slide and become longer during the night, but it wasn't a bit problem and I'll keep an eye out once I buy a replacement to see if it was just a fluke breakage. I can't say if it's really working, as teeth grinding is a very gradual process and mine was never severe enough where I would wake up with jaw pain and headaches, but I do see bite marks on the padding so it's doing something.
I would give this a try if the boiling type frustrates you as much as it did me.
