Probably the most important thing to have in a beautiful smile is that ALL of your visible teeth should be one colour.
Old worn out fillings can impart significant discoloration to a tooth. This becomes even more evident if there are bacteria leaking around the filling. Corrosion by-products of a silver filling placed near the front of the mouth can leave the tooth bluish or even black in colour. The simple replacement of this material with a new modern tooth coloured material can restore a tooth to its original beauty.
Why replace old fillings?
Dark old fillings impart a displeasing dark colour to the tooth structure surrounding them, and for many people, this is a good enough reason to replace them. However, there are other reasons to consider replacing them.
As a white filling becomes ‘unglued’ from the tooth surface, bacteria can leak in around it. At the start of this process, you will see a brown line around the filling. In time these stain producing bacteria will surround the filling to further discolour the tooth. Eventually, they will destroy tooth structure as decay.
The problem is worse around a silver filling as it’s very difficult to see the early stages of this process, and x-rays aren’t always helpful.
Excessive tooth structure loss due to decay associated with white and silver fillings will lead to stress on the nerve of the tooth and cause further weakening of the remaining structure.
Stopping this leakage process early on will serve to preserve more tooth structure. Root Canal Treatments (RCT), crowns or even tooth extraction is the eventual consequence of severe structural loss.
Old amalgam fillings that have been in place for longer than ten years should often be looked at for replacement. This is because the statistics suggest the likelihood of fractures being involved with the remaining tooth structure that surrounds the fillings after this time is quite high. To make matters worse, it’s very difficult to diagnose such fractures as they will rarely show up on x-rays, and they only cause symptoms when they are about to completely break through – very often too late for the tooth.
What do we replace old fillings with?
The material that we restore a tooth with is dependent on the amount of tooth structure that remains after all old filling material, decay and fractures are removed. The rigidity of the remaining structure and whether it can support itself, or if it needs further protection is what we try to assess.
There are three basic options:
If 60% or more of your tooth structure remains, composite resin is generally a very durable and long-lasting restoration option. It has been shown that when there is more than 40% of your tooth structure lost, 90% of its strength is lost.
Porcelain Inlays and Onlays
If only 40% to 60% of your tooth structure remains, they would be better protected with Porcelain inlays or onlays. These are much stronger that Composite resin restorations. They are produced in a laboratory and take two visits to complete. At the first visit, an impression is taken of the prepared tooth which is sent to lab. A temporary inlay / onlay is placed to protect your tooth until the next visit. At the second visit, the temporary restoration is readily removed, and the new porcelain restoration is bonded into place.
If only 40% or less of the tooth structure remains, there will not be enough structure to support an inlay / onlay, and a crown is a better option. The crown is produced in a very similar fashion to the inlay / onlay, but it more completely encapsulates the remaining structure. Therefore, it provides a greater splinting effect.
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