Fillings and Cavities are two words that will be forever attached at the tooth. Fillings are the common aid to that familiar pain that we have all experienced at some point, the cavity. You can usually tell when you have a cavity because you will be sensitive to hot and cold and of course, sweets. Cavities are formed when acid found in plaque erodes through the two outer layers of the tooth, the enamel and the dentine. Once this erosion has taken place it is time for a trip to the local dentist for a filling.