Hi Conor.
Scubasean is correct. Using proper technique is all that is necessary to place a "dive proof" filling.
That being said, you should know that even when experimenters tried to create voids under fillings, the occurence of problems related to pressure was extremely low. It is my belief that a simple void under a filling does not in itself cause a problem diving. There seems to be the need for co-incidence of pulpal inflammation in order for the tooth to become symptomatic.
There are two basic types of filling materials commonly used today. Amalgam, a mix of silver, with zinc, tin, or copper plus mercury to form a plastic mixture that hardens. Composite, a plastic with quartz or glass particles mixed in.
For those concerned with the mercury, composite is the appropriate alternative. If you want cosmetics, again, use composite. Please be aware that there are no toxicity studies of composite. We know that there are biproduces of composite that mimic estrogens. What this may cause is unknown as is any other toxic effects. Using composite to avoid the mercury in amalgam is simply trading one unknown for another.
If you want long term durability, use amalgam.
Both filling materials have drawbacks. Amalgam has poor edge strength and chips occur at the interface between the filling and the tooth. Amalgam exhibits microleakage when first inserted. The leak is "sealed" by corrosion products. With time, however, the corrosion progresses and may result in a fracture of the tooth. The initial shrinkage may cause temporary temperature sensitivity which usually goes away in 1-2 weeks...when it happens. Placement over a sedative lining cement will reduce the incidence of this.
Composites also shrink when hardened. Since it is now common to "bond" them to the tooth, the filling remains attached to the tooth but stress is created which pulls on tooth structure. This stress may cause sensitivity.
Additionally, composites are EXTREMELY technique sensitive. The filling must be placed in a dry environment...but the tooth can be moistened with one of several wetting agents. Failure to do so can cause severe sensitivity.
Composites and amalgams are both rated to last approximately the same length of time. In reality, amalgams last much longer. Composites are more likely to get recurrent decay than amalgam. They are a second choice in areas of the mouth that receive high chewing forces or are subjected to a lot of clenching. While the composite can be bonded to tooth and can make a tooth almost as strong as it was before filling, it wears at a greater rate than silver amalgam.
The choice is the patient's with guidance from their dentist. I would prefer to have the stronger filling material.
For teeth that have been filled a number of times or for teeth which have large fillings, crowns or onlays are more appropriate.
Let me know if you have more questions.
Regards,
Laurence Stein, DDS
:doctor:
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