Nightguard without molding?

[vassock]

My dentist recommended I try a store-bought nightguard for my nighttime grinding. I bought one of the ones you can boil and mold. I was wondering if it's OK to use without molding. Can it cause any damage that way? What about a mouthguard that isn't ideally molded?

 

[Busybee]

You should have a custom made night guard. I don't understand why your dentist recommended a shop bought one. The wrong type/shape guard can cause more problems than it fixes.