Are the mouthguards on the internet as good as the one from the dentist?

No: The ones from your dentist are custom made devices utilizing models which are fabricated from impressions taken of your teeth. They are thus considerably more precise and expensive. The over the counter, internet ones are basically boil and bite devices, not well fitting, need to be replaced often, sometimes come in small and large and you use the size that is the closest.

Not really: There are many types of mouthguards for grinding and clenching. Over the counter ones actually may be too thick and throw the muscles into more spasms. Dentists can make custom made, well fitting mouthguards, either upper or lower (i like the lower ones.) the guards can be made of soft plastic or hard acrylic...Depends on severity of grinding. For daytime clenching, other types are indicated.

No: The ones that your dentist make are costum and have a better fit and functionality. Over the counters or the ones on the internet are more for temporary basis.

No: You need a hard nightguard adjusted especially to your bite.

No: But, the cost between the two is often too much for someone to spend on the custom fabricated guard.

Not even close: "One size fits all" is an oxymoron. Does a suit bought over the Internet fit as well as a custom made suit? Your Dentist has years of training and experience. Your computer has a screen. 'nuf said.