How Often Do Cerec Crowns Fail?

In the hands of a skilled and competent dentist, CEREC crowns and onlays/inlays work well. However, I see alot of people coming in with poorly done CEREC restorations. It seems as though there is a steep and long/tall learning curve. Some dentists do not seem to ever get thru the learning curve. Quite often they are poorly cemented with gaps at the margins or excess cement that cannot be cleaned off. I also believe there is tendency of dentists to overprescribe CEREC crowns when a direct composite filling would work fine. Typically the patients insurance will pay 80% of $150-$330 for a filling vs. 50% of $600-$1200 for a CEREC restoration. This is a huge difference in the out of pocket expense for the patient. The dentist  has $100,000 invested in the CEREC system and has to pay that overhead so it seems like CEREC is being over-utilized. The old saying..."if all you have is an (expensive) hammer, everything looks like a nail ! "

 

CEREC crowns do not fail more often than traditional crowns.  Any crown will fail if it is not designed properly.  The crown must fit the bite both when the teeth are closed and in function.  The tooth must be prepared to provide enough thickness for the crown to maintain structural integrity.  The margins of the crown and tooth preparation must be matched so that a proper seal exists, even before cementation.  Home care is also an important factor, since a healthy environment around a crown promotes longevity.

Although the CEREC technology to provide a single visit crown in the dental office is limited in availability, a significant number of professional dental labs are using CEREC technology to fabricate their crowns. 

With todays technology, a skilled dentist using a CEREC machine will be able to fabricate a crown that is equal to any lab fabricated crown.  In fact there are many labs that are now utilizing CAD-CAM technology to fabricate their crowns.  The real factor to the longevity of the crown, if done well, is the home care and habits of the patient.

I have found over time that the most predictable type of restoration is one made out of gold.  However, many people these days dont want metal in their mouth.  Gold is almost unbreakable and can be cemented in with a traditional easy to use cement.  Cerec crowns are made out of porcelain which is in most cases not as strong as gold.  Cerec also must be bonded  rather than cemented, which means that it requires more steps that have to be followed very carefully.  It is much harder for your dentist to do a "good" cerec crown, than almost any other crown available.  So you want to make sure you are going to someone with plenty of experience with Cerec and find out if they have a warantee of any type in case something goes wrong. Also, cerec restorations tend to be more predictible in certain areas of the mouth like the front and sides vs. the very back teeth, and in people that do not grind or clench their teeth.  The beauty of Cerec is that it can be done in one visit and if done properly, under the right circumstances, it can provide a predictable, reliable result that looks great.  We have done over 1000 cerec restorations in our office and they are more reliable today than ever before.

the lifespan of a cerec or any type of crown really depends on the patient and the dentist. If the dentist is being very meticulous with the occlusal components, the life span is longer. If the bonding process is followed to the exacting specifications that are indicated, then you will get a better result. If the patient does not keep good homecare and does not visit the dentist regularly then the reults will be less predictable. It does seem that lots of education is needed for dentists to be able to fabricate esthetic cerec crowns so make sure the dentist is doing the design and milling and not cutting the preparation and leaving the room for an assistant to do the design phase (which is the hardest sometimes!)

But if the dentist using CEREC doesn't learn how to do them well, they will fracture more easily than a lab made crown.  Not all dentists are created equal, so some homework is needed.  The right material needs to be used, the tooth preparation needs to be designed correctly and the crown needs to be bonded correctly as well.

Cerec is a great product with amazing software potential. However, originally created for inlays/onlays they widened their makret by pushing Cerec crowns, "same day crowns" for general dentists. Milled Cerec crown which is done in the office and usually not even glazed in the oven, is t immediately cemented on the patient`s tooth. There is no underlying research showing that Cerec milled restorations strength, long-term success can be compaired to lab-produced metal or zirconia crowns. As a specialist I don`t believe in short-cuts and can recommend Cerec only as a temporary solution to protect to tooth before the permanent crown. 

There is no set life time for ANY Restoration. I have seen 20 year old crowns that still are good, and I have had patients coming in with a prior crown that was less than a year old and was failing. Same thing goes for cerec, all porcelain , gold, whatever crowns !

That is because there is so much involved , and variety of factors. Such as laboratory used, expertise of the dentist,  " bite issues", clinching, grinding, crowding, the extend of disease on the tooth, hygiene.,genetic factors........