Basically, a cavity is a hole in the tooth. It has 3 main stages:
Incipient decay – the beginning. This is the only stage where you can stop it from getting any bigger! It is still localized in the enamel and with good brushing, flossing and good dietary habits it can be stopped (arrested decay).
Small to large cavity. This phase can last up to 4 years, until it progresses towards the pulp (the nerve). During this time, you may or may not experience pain or sensitivity. The sooner you fix it, the better off you are! The solution is a simple filling.
Decay has reached the pulp chamber. At this point in time there is serious damage to the tooth and you will experience pain and/or infection. The remedy is root canal therapy or extraction of the tooth.
As a cavity progresses, the treatment gets more complex, time consuming and costly. This is the reason we advocate good home oral care: brushing and flossing – regular dental check-ups and cleanings: with X-rays taken once a year – and good dietary habits such as decreased sugar intake, enough calcium and vitamin D etc.
Special mention: Recurrent decay. This is decay under an older restoration. There are billions of bacteria in our mouth, constantly attacking the tooth. Even if you receive good quality fillings, they need to be maintained and cleaned. The average lifespan of a filling is 8-12 years. Every time you need to replace a filling, the size will increase. Therefore, the sooner you fix them, you extend the life of the tooth.