Lumineers and Teeth Grinding

The short answer is yes, there's a higher risk of Lumineer fracture or separation if you grind your teeth.  Whether or not your Lumineers will be damaged from not wearing your nightguard depends on your bite and the amount of pressure that exists between your front teeth when you bite down.  That's something that your dentist can determine.  My advice is that after having invested thousands of dollars in your Lumineers, you should not risk it and try to get used to wearing your nightguard.  You should also have your dentist make sure the guard itself is not placing excessive pressure on the front teeth.

any type of porcelain veneer is likely to chip, crack, or de-bond if habitual griding of the teeth occurs. A night guard should be worn every night and every time you take a nap. There are many kinds of night guards if you are having trouble adjusting the one you currently have.