Fillings and Bonding
COMPOSITE RESIN FILLINGS (WHITE FILLINGS)
Composite restorations have a natural, tooth-like appearance and are used primarily on anterior teeth, although many patients now prefer to have composite fillings placed on posterior teeth. A major advantage of this type of restoration is that they match the tooth colour and are aesthetically pleasing.
Composites are made of a mixture of plastic and acrylic materials such as polymer matrix, quartz and lithium aluminium silicate. Polymerisation is a process in which a resin material changes from a plastic state into a hardened restoration. They are also capable of bonding directly to the tooth structure reducing the possibility of leakage.
The length of time that it takes to perform a composite resin restoration depends on the size of the restoration. Some restorations will only involve one surface and may not require anaesthetic, so the appointment may only take 10 to 15 minutes. When the procedure involves more surfaces of the tooth, the procedure may take longer. A composite resin restoration will restore the tooth to its original function with an aesthetically pleasing result.
SILVER (AMALGAM) FILLINGS
Amalgams are commonly known as silver fillings. They do contain some silver; however, they are a mixture (or alloy) of metals that are bound together, or in other words, amalgamated. Traditional amalgam fillings were bound together by using mercury; however, many of the newer amalgam materials do not use mercury. Amalgam fillings have been used for many years and are often the preferred treatment for posterior fillings.
The average biting force in the posterior jaw is approximately 170 lb. of pressure. A dental restoration must be able to withstand such forces. Amalgam fillings do not change easily under stress and are soft, pliable and easily shaped into the prepared cavity. The amalgam then hardens quickly to form a very strong dental restoration able to endure the stress associated with chewing and biting. With specialised dental bonding systems, it is possible to create a bond between the amalgam and the tooth structure. This reduces the possibility of leakage or recurrent decay forming beneath the restoration.
Metals, as those used in amalgam restorations, are excellent thermal conductors. They rapidly transmit heat and cold through the tooth. Amalgam fillings help to protect the pulp against sudden temperature changes. The retention of this type of dental restoration is excellent and can last many years within the mouth.