Cavities are a very common dental problem that nearly everyone has had to deal with at some point in their lives. Cavities are exactly what they sound like they are: holes that appear in teeth due to decay. These can cause serious problems unless they can be filled by a dentist. Bacteria can gain access to the interior structure of a tooth through a cavity and cause further damage which can become severe and virtually irreparable over time. Fortunately, there are relatively simple methods that a dentist can use to fill cavities in teeth.