Question:
            Dr Antolak,  I read your article in the Senior Living Newspaper and I have several questions.  I have two crowns, close to the front of my mouth,  which are starting to chip off at the gum line.  One dental crown is combined with gold, the other with silver.  I have my teeth cleaned twice a year but the doctor never says anything about the chipped crowns.  Both crowns were done in his office years ago.  You stated in your article that dental crowns are very strong, then why are mine chipping?  What can be done other than replacement crowns?  What is the price of a dental porcelain crown?  I am a senior citizen with no dental coverage.  Sincerely H.E. Row  Roseville.
 

Answer:
Dear Mrs. Roe,  Thank you for submitting your question to me.   You bring up some fundamental questions that should be addressed to your cosmetic dentist.  First of all, does he know that you are unhappy with the appearance of the crowns? I have found throughout the years of treating fearful patients that communication is so critical and the lack of communication can result in serious misunderstandings.  It may be possible that he knows that you are in a financial limited position and the crowns may be functioning ok.  He may not want to burden you with additional costs due to the high cost of dentistry.  There are certain levels of breakdown that can take place and are still considered functional.  I would recommend telling him that you are unhappy with the appearance of the crowns and ask him what can be done with them. 
The following may be possible answers to your question:
The tooth colored crowns can be patched up with tooth colored composite resin to cover the open areas under the crown.
He may state that the crowns are doing just fine and he may keep an eye on them to see if they get worse.
He may recommend that the porcelain crowns be replaced if the level of breakdown is to the point of disrepair. 
 

Now to answer your question about why they may be chipping:
When teeth are stressed and the crowns break down and are moved side to side/or if you grind on the ends of them, they flex at the gum line.  This flexing movement may slowly chip the porcelain away at the gum line and over time this may lead to grooves where the tooth meets the bone.  You may even notice this type of groove on other areas of your teeth.  These are known as abfractions.
 

Abfraction lesions can be confused with recession in that they both are responsible for increased areas of tooth exposure.  The difference is that abfractions usually leave a deep groove just above the gum line. Recession appears as a smooth area of thinned tooth and gum tissue next to each other.  Recession can be caused by using a hard toothbrush and brushing very vigorously.