Dental problem needs treatment but no insurance. Is there any dentist here? Want to know about crumbling crown.

Dentist here... As a dentist, i can help you and answer questions about your crowns. What is your question? Is the crown of your tooth crumbling from an old filling? Or have you had a dental crown (or cap) made for your crown in the past, that now is causing you a problem? Dental issues can be expensive to fix, but they do not go away on their own. They tend to get worse and most costly as time goes on.
Check dental clinics. Dental students need practice and in some school/clinic setting, many patients with dental problems can be cared for free of charge at these places! some do beatiful work! they are dental students, but are supervised by highly trained dentists/orthodontists so your care is generally safe! dental care is expensive, so getting these done for free is a no brainer! good luck.
Proper care. Unfortunately good dental care is expensive. Quick fixes and dental bargains often turn out to be the most costly outcomes along with the grief and aggravation when one experiences problems along the way. Find a dentist who comes highly recommended and whom you trust and who makes sense regarding the diagnosis and treatment plan. In the end you will save money and be happier with the outcome.
Lots of options. I think you have some options, but you may need to travel outside of marina del rey 5-20miles. I've seen crowns advertised in certain parts of socal for as low as $300 in the local pennysaver or even craigslist. Not sure who the dentists are, but at least you have options on less expensive dental care. I also know of an insurance plan with $135/yr premium and $350/crown copay with 2 cleanings $25.