If you have been clenching your jaw tight enough to damage your teeth even with a nightguard, you face a problem. You need to get crowns to repair the damage to your teeth, but you then might end up damaging the crowns as you continue to clench your jaw in your sleep or during stressful periods in your life. It seems like a no-win situation, but there really is a solution—in fact, more than one.
Crowns are typically made of materials like porcelain because those look the most natural, but you can also get a crown made of gold. Gold is a very gentle material that doesn't react with people's mouths as much as other metals do. Gold crowns are actually alloys, so there are other metals like silver in there, but even then, the chances of an allergic reaction are still lower than with other materials. Gold is also resistant to damage from jaw clenching -- damage can still happen, of course, but you're less likely to suffer it with a gold crown. The drawbacks are a high initial cost (the longevity of gold crowns eventually makes them good deals), plus the fact that you have a distinctly un-toothlike tooth visible in your mouth when you smile.
Another tactic is one you're likely already trying, but you can put new effort into it: looking at what's causing stress in your life. If you haven't already done so, start keeping a record of daily events and of who you see during the day, and whether you ended up clenching your jaw in your sleep, in the car during a traffic-filled commute, or in another situation. Even if you've been trying to address the clenching, now you really have to step up the effort to find the cause because the clenching has started damaging your body. That can't go on; you can't just keep getting new crowns every few months because you've chewed through the last one.
If you're really having trouble stopping the clenching, and you're afraid your new crowns will only fail instead of protecting your teeth, you may want to look at Botox. The American Academy of Facial Esthetics notes that one treatment of Botox can soothe bruxism, aka tooth grinding and clenching, for about three or four months. That would allow you to get new crowns without the fear that they'd be damaged again quickly.
Make a consultation appointment with your dentist again to go over the possible solutions that would keep crowns intact. You really can find a way to do this. Contact a clinic like Carpenter Dental to learn more.