Restorative dentistry typically refers to the procedural use of “dental filling material”. There are several types of dental fillings used currently in the United States and the rest of the world.
There are two main classifications of filling material:
Bonded restorations are typically known as white restorations or composite fillings. They are essentially made of plastic and glass. They are bonded to the tooth with adhesive made of similar material. Once the filling has been placed into the cavity it is cured (set) into place by means of an ultraviolet light.
Bonded restorations are very sensitive to fluid contamination prior to being cured. Therefore isolation from saliva during placement is a key factor to their long-term success. Composite restorations, which are subject to fluid contamination prior to curing, will have leakage at the tooth-filling interface. This will eventually lead to decay at that interface and possibly lead to decay spreading to inaccessible areas beneath the filling.
It is vital therefore to use a rubber dam or ensure proper fluid isolation when bonding any material to the tooth.
We employ several types of composite material for bonded restorations. Each composite has its unique characteristics which make it suitable for its intended application.
For instance as the luster and polishability properties of a composite increase its strength decreases. Obviously luster and polishability are very important for proper esthetic outcomes where as strength is very important to wear. So in the anterior areas (front teeth) of the mouth highly polishable less strong composites are generally used. In the posterior areas(back teeth) of the mouth less polishable stronger composites are generally used.
Finally there exists a classification of white materials which “auto-bond” to tooth structure. They are known as glass ionomers. They have been used in dentistry for over 50 years. Glass ionomers tolerate moisture contamination very well. The downfall of glass ionomers is they are too weak for stress bearing restorations. Thus their best application is for fillings close to the gum margin where there is little stress and moisture isolation can be difficult to achieve. They also work well as a lining material under fillings to help prevent post-operative sensitivity.
Silver filing material aka dental amalgam is the most ubiquitously used non-bonded filling material in the world. Dental amalgam is safe and effacious. Its main application in our practice is for any filling where moisture control is impossible.
Amalgam seals the cavity by creating a mico-layer of silver oxide (silver rust) between the filling and the tooth. The formation of the seal can take up to three weeks following the placement of the silver filling. This is one reason silver fillings can be sensitive for a while after they are placed.
As dental materials improve we have been using less and less amalgam in our practice. Currently about 95% of the restorations we place are non-amalgam.