My two front crowns keep break. Bad product? (photo)

There are a few reasons why a crown would keep coming off.  One is if there's not enough tooth structure underneath to retain the crown in place, another is the type of cement used.  One more contributing factor is your bite.  If you have a deep bite anf keep biting hard into the crown then the crown will come off.  You need to have this re-evaluated by your dentist and look at other options.

To answer your question about your porcelain crowns cracking, I need to give a little background information.There are two basic kinds of porcelain crowns, or caps as you call them, and then sub-categories. There are porcelain fused to metal crowns that practically never crack, and there are all-porcelain crowns which are strong enough for the front teeth but can crack sometimes when used on molars. But now, even with all porcelain, there are zirconia ceramics that are extremely strong.And then there is a wide variety of patients, as far as the strength of their bites. There are some that I call “gorilla bites” that will break things in their mouth really easily. That happens with fewer than 1% of patients. Most practices will have a handful of those patients, and they can break a tooth clean off, but the porcelain fused to metal crown will stay intact.What I want to say with all of this is that, even with good dentists, there is often a learning curve of dealing with real patients where they do what they were taught in dental school but the patient still breaks things. The way to tell if you have a good dentist or not is their attitude about this. If this makes them upset and they take extra pains to get it right and they fix things at their expense, then I would stay with the dentist. Maybe the dentist used all-porcelain and it really should have been porcelain fused to metal on this particular tooth. If I were the dentist, I would apologize for the mistake, and replace the crown, maybe waiving your portion of the cost if there is dental insurance involved, or even doing it completely for free. However, you seem to be saying that the dentist is trying to brush it off as normal, which makes it sound like this happens a lot with this dentist. If I were the patient, this would not be acceptable to me.Now most dental insurance companies will not pay for a new crown if the old crown on the tooth is less than five years old. But a crown really should last considerably longer than that if it is done well – 10, maybe 20 years or even more.And then, it isn’t that uncommon for a tooth that has a crown to also need a root canal treatment, either before the crown is done or afterward. But if this happened a lot to you and the crowns weren’t done for decay but as part of a bite reconstruction, then I would question the work.