We often see patients with cracked teeth.  Did you ever wonder what might be the cause?  When growing up if we had a cavity most of us received an amalgam (silver-mercury) filling to restore it.  Amalgam (silver-mercury) fillings were common.  The problem with silver-mercury fillings is what they are made of and how they are used to fill a tooth.  Usually the decayed area of the tooth is removed leaving a “hole” behind.  Silver-mercury filling material is them mixed and placed in the hole.  No adhesive is used so there is no seal provided to the tooth.  Without a seal, saliva and other materials can slowly leak under and around the edges of the filling.  As this occurs over time slowly the tooth can get a new cavity deep underneath the filling.  This new decay can go undetected for years not being seen through the tooth or even visible in an x-ray until it is too late.  When chewing on the tooth suddenly the silver filling can shift causing the tooth to crack.  Also, once you realize that silver-mercury fillings are made up of 50% mercury you can understand how they crack teeth.  What happens to mercury in a thermometer on a cold or hot day?  It expands and contracts depending on the temperature.  Well, silver-mercury fillings do the same thing when we eat something hot or cold.  They also expand or contract 6 times more that the tooth.  Expansion and contraction of the silver-mercury filling inside the tooth pushes against the parts of the tooth eventually causing it to break.  We often recommend removing silver-mercury fillings for these reasons.  A variety of other options such as, porcelain restorations, gold restorations and composite restorations are available to restore your tooth to its natural strength and appearance.