I believe they are an excellent choice, because they do not have quite the chemicals that composites have, they are stronger/harder and do not tend to leach their components. However, in saying this, some or all (not sure) contain aluminium oxide. But so do many other dental materials. And as there is no such thing as a metal free, chemical free dental material, one has to try and make the best choice they can. I hear that the aluminium in them (oxide) is bound up and according to Walter Clifford, one would likely get more aluminium from their own diet, than they would with a lifetime of ceramics. Not sure what to think.
There are some porcelains that maybe better and more biocompatible than others. Some claim cerec doesn't contain aluminium, some say it does. I would steer clear of any porcelain that contains a metal base, and I would tend to chose a ceramic porcelain such as Cerec or something similar. They seem to be better than the old style porcelains and more biologic dentists seem to be taking this material onboard also, not just becuase of it's mechanical properties, but also biocompatiblity. It appears to be very well tolerated.
However, that is not to say nobody has or ever will have a reaction to it, everybody is different.
They are very expensive, and to reduce cost, you should ask around (phone or email) and get an idea of cost. You can sometimes also get a reduced cost if you get 3 or more done in one session. They can cost around 800 or more a tooth (this is NZ dollars, I do not know what that is in US dollars)....They also eliminate the need for a crown. They expand and contract with heat and cold and apparently are the closest material in resembling enamel.
For those who are reactive to plastics, this may also be a healthier alternative. Some prefer composites, others prefer porcelains, there is a lot of contradictions out there, so it's very hard to anybody to make the right decision. You may find this link interesting
http://www.drheise.com/dental.htm Please scroll down to
" Selecting Biocompatible Materials" where you may get at least one idea of what materials apparently have been shown to be most tolerated long term. Keep reading from then on, it also talks about ceramics etc, which they believe (at least the ones they've mentioned) to be the best tolerated. This may help you, I hope it does.
The one thing I disagree with on that page is the fact they claim that candida should not be treated in mercury toxicity. I found candida made my mercury toxicity FAR FAR worse and without treating it, I was a basket case. I was more toxic, I was unable to detoxify properly, and unable to handle the mercury in me. The candida messed up my gut and liver, made everything, including my brain more toxic and I spent most days bedridden, severely depressed and suicidal. Treating candida probably saved my life, though I advise treating it with diet alone, rather than antifungals, as they can kill of candida aggressively, possibly releasing any contained metals from the candida itself, which can cause acute poisoning in some cases. Reducing candida naturally by a healthy sugar free, gluten free, milk free, high carbohydate free diet is the way to go. Not only does it reduce excessive yeast levels, but it aids the immunity and aids healing. The worst culprits I think are sugar and wheat/gluten.
On my serum test form, I showed to be suitable to all milling block porcelain (eg. cerec). Not one of them showed unsuitable. yet I am pretty metal and chemically sensitive, plus I tend to hold onto toxins, rather than eliminate them. I have had cerec put in pretty recently and haven't noticed much change personally, but I replaced my composites with them because they were due for change and were old and tend to shrink also. Decay can also go on underneath often without detection. I paid alot for these cerec replacements and still paying it off, but i'm trying to look at the long term picture. I get ill everytime I enter a dental office, due to vapor exposure, plus anaesthetics etc. So hopefully with these cerec replacements, I may not need to go again for many many years. Supposedly they can last near a lifetime - or about 25 years +
It really is individual choice, individual reaction. Very hard to say what is going to suit each person. I hope I made the right choice, hard to say, since I am dealing more with immune/viral related issues which have been with me since 2003, so my symptoms are much more related to infections, than anything else these days.