I've recently started krav and my studio gave me a boil-and-bite mouth guard that is WAY too big for my apparently tiny mouth. I trimmed the ends so it doesn't make me gag, but it's still too tall, especially the inner walls. I can barely close my mouth and the guard's inner walls dig into the roof of my mouth.

My question is whether I should just boil it and assume the inner walls once softened will sort of bow inward to curve towards the center of the roof of my mouth and run alongside it instead of just digging into it, or if I should trim the inner walls so they don't come up as high into the roof? I'm afraid that if I try either one and it's not the correct approach I'll have ruined the mouth guard.

I've been trawling Google for help but all the sizing advice I can seem to find is people talking about trimming the ends, not the walls, and a bunch of results related to ill-fitting night guards for people with dental problems.


3 Answers 3


If you want a boil mouth guard and the adult version is too small I recommend going for a youth version. In general it's just plastic so you can cut it to fit if you want, but naturally starting off with a smaller mouth guard and then trimming will require less trimming than a standard adult one. So long as it clings to the teeth and you can close your mouth with a solid guard it should be good.

  • As soon as you trim it, however, you void any possible dental guarantee that the manufacturer may have on the product, because you have altered it.
    – JohnP
    Commented Sep 11, 2017 at 15:33
  • True, although I have never found those that useful as even with issues they only pay for minor stuff and usually find a way to get out of paying altogether. That's just me though as I'm sure there are some people who are more successful. I find making it fit and protecting to be far more benefit than a dental warranty on a factory product...especially if the product doesn't fit anyway.
    – mutt
    Commented Sep 11, 2017 at 16:56

I would personally recommend the Shock Doctor line of mouthguards. They are the boil and bite method for fitting, and they come in several different adult sizes as well as youth sizes.

They also have double (upper/lower) as well as the single upper. I've found them to be very comfortable and don't interfere with my breathing, and they come with a fairly hefty dental warranty, but not sure how worth it that part actually is.

Also, if you can't find a youth one that fits, some dentists will be able to custom mold a mouthpiece for you that will fit your mouth specifically, but I am not sure of the $$ cost of that.


A dentist can fit you with a guard that will fully fit your teeth and mouth. It might be on the expensive side (I have no idea on prices and/or insurance) but might save you lots of pain and possibly more dental work.


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