There has been a lot of progress made in the area of filling materials for teeth with small areas of decay. Previously, silver amalgam was the major choice for dentists. One downside of these silver fillings is that they are held in mechanically and the dentist has to undercut the preparation to get it to lock in to the tooth. This results in the removal of good tooth structure to get it to mechanically lock in to the tooth. Because they did have to make a larger opening to put in a silver filling, dentists were many times reluctant to fill the smaller cavities, waiting until the cavities were bigger to put in larger fillings. The larger a silver filling gets, the more discrepancy there is in the coefficient of expansion. This means the metallic fillings will expand and contract more than the tooth structure it is in when making contact with hot and cold foods. When this happens over an extended period of time, often times the teeth will crack or the margin between the filling and tooth will break down, causing leakage. The biggest problem found with baby boomers who received these large silver fillings when they were young is most of them needed crowns as they grew older. So now there is a push to perform less invasive dentistry and the composite resins have come a long way from previous generations. The composite tooth color restorations wear more like tooth structure now and they bond to the tooth so the dentist doesn’t need to rely on undercuts. This allows us to remove just the decayed area itself and bond the filling into the tooth, preserving more structural integrity to the tooth.
Because we are taking care of decay at an earlier stage and using fillings that bond to the tooth that have a coefficient of expansion that is more similar to the tooth structure, there are fewer cracked teeth caused by the restoration, the fillings are smaller so they last longer, and cosmetically they blend to look more like a natural part of the teeth.
When fillings get to be a certain size, regardless of the material, you are exceeding the limits of that material for it to be an effective restorative product. In this case, porcelain restorations can be shaped and cast to fit in or on the tooth and bonded to the tooth. This solution can be effective for teeth that need full coverage to protect where they have been cracked or broken. Often times now we don’t have to do a full crown when we can do different shaped restorations that bond to the teeth and maintain more structural integrity to the tooth.