Tooth decay or dental caries occurs when in a cavity form in teeth. It occurs when bacteria in your mouth produce acids that erode away at a tooth. If decay goes untreated, this can cause pain, abscess or even tooth loss. The dentist will examinine your teeth to establish if there is any tooth decay. If it is early decay that is within the enamel (the outer layer of the tooth) then a filling may not be needed but just preventative measures such as flouride application and oral hygiene instructions together with dietary advise. If the decay is deeper then treatment options will be discussed so that you can make an informed choice. Depending on the extent of decay, treatment options can include: a conventional filling, root canal therapy or a tooth extraction.