I was apprehensive about buying a mouthguard online, but I had been in such pain due to my night tooth-grinding and clenching that I had become desperate. The mouthguard came very quickly (thankfully!) and as I had read the other reviews about being very careful when preparing and moulding the mouthguard, I followed the instruction booklet that came with it very carefully. It moulded to my mouth perfectly and I had no problems with it.
After 1 night of wearing it I immediately felt the benefit - my jaw no longer hurt and my teeth weren't sensitive. It is very comfortable to wear and I didn't need to trim it or anything. I wear it every night and every time I nap now and it seems very sturdy after the week I've been wearing it.
It is not only beneficial for grinding, but I have a big problem with jaw clenching, and because of its shape on your upper teeth it realigns your bottom jaw to sit in the correct position, and really makes it difficult to clench. Also it doesn't create a lot of saliva which was my other concern, and it feels very safe and secure in my mouth.
I just use 1 of the guards on my top teeth, the other one I keep as a spare.
Truly fantastic product, would highly recommend!