Cavities occur as a result of tooth decay. Tooth decay is the destruction of tooth structure. Tooth decay can affect both the enamel (the outer coating of the tooth) and the dentin (the inner layer of the tooth).
Tooth decay occurs when foods containing carbohydrates (sugars and starches) such as breads, cereals, milk, fizzy drinks, fruit, cakes or sweets are left on the teeth. Bacteria that live in the mouth digest these foods, turning them into acids. The bacteria, acid, food debris, and saliva combine to form plaque, which clings to the teeth. The acids in plaque dissolve the enamel surface of the teeth, creating holes in the teeth called cavities, or caries.
Many people think cavities only affect children, but changes that occur with ageing make cavities an adult problem too. Recession of the gums (a pulling away of gum tissue from the teeth), often associated with an increased incidence of gingivitis (gum disease), can expose tooth roots to plaque. Also, sugary food cravings in pregnant women can make them more vulnerable to developing cavities.
Decay around the edges of cavity fillings is also common in older adults. Because many older adults lacked the benefits of fluoride and modern preventive dental care when they were growing up, they often have a number of dental fillings. Over the years, these fillings may weaken and can fracture, allowing bacteria to accumulate in the tiny crevices causing tooth decay.
Your dentist can discover cavities during your regular dental check-up. The tooth surface feels soft when probed by your dentist with a dental instrument. X-rays can also show cavities before they become visible to the eye.
There are a number of different treatments for cavities depending on the extent of tooth decay. If decay is not extensive, the decayed portion of the tooth is removed by drilling and replaced with a filling made of silver alloy, gold, porcelain or a composite resin.
Materials used in fillings are considered safe. Concerns have been raised over the safety of mercury-based, silver amalgams in particular, but the British Dental Health Foundation continues to support the safety of this restorative material. The British Dental Health Foundation states that there have been no reputable studies that have found conclusive evidence to prove a connection between amalgam fillings and any medical problem. Allergies to silver amalgam are rare as are allergies to other restorative materials.
If the tooth decay is extensive and there is limited tooth structure remaining, crowns will be used. If a crown is needed, the decayed or weakened area of the tooth is removed and repaired and a crown is fitted over the remainder of the tooth. Crowns are made from gold, porcelain or porcelain fused to metal.