Tooth decay is not dissimilar in appearance to bad spots in a potato. It is soft and yellow/brown but unless there is a lot of decay there may not be an actual cavity. A tooth is a bit like a pumpkin too, really hard on the outside and softer the further in you get. If tooth decay is only in the hard enamel it can heal out and we don’t fill those teeth. However as it burrows deeper into the softer parts of the tooth fillings become necessary. It is important to realise though that fillings don’t strengthen teeth - Nothing is ever as good as the original! If a tooth is filled too much it can be like a shopping bag being stuffed until it bursts. This is when crowns become necessary to save teeth.
is the old, black metal material that almost all of us have in our back teeth. It was strong and lasted well but because it is black and contains mercury, we don’t use it any more. In fact we don’t even have it.
is plastic and works nicely in small cavities. It is routinely used for front teeth. If composite fillings are big and there is hard chewing done on them, they fail after a few years; new decay easily formes under them.
is a white fillings material that can be used in back teeth. The advantage is that new decay doesn’t form too easily under it but on the other hand glass ionomer is brittle and hard chewing fractures the material.
has worked well for many years and is strong and seals well. The down side though is the cost and some people just don’t like gold in their teeth. Still for back teeth it is an option.
is also strong and last well. It can be colour matched to be indistinguishable from the tooth but the cost is high.