The most common - and most preventable - problem affecting children's teeth is dental decay or caries.
Causes and risk factors
The problem is caused by sticky deposits called plaque that collect, in particular, around the gum line, the edges of fillings and the grooved surfaces of the teeth.
Plaque is made up of food debris, saliva and the bacteria that are normally present in the mouth, and convert food into acids.
If plaque is allowed to collect over time it will harden into a substance called tartar. Both tartar and plaque contain acids which, over time, can dissolve away the protective, hard enamel coating of the tooth, and create holes, or cavities.
Most cavities form over a period of months, or even years.
They are usually painless, but they can grow very large, and damage the much softer internal structures of the tooth such as the dentin and the pulp, which is found at the core.
If they remain untreated, they can kill the nerve and blood vessels of the tooth, and ultimately the tooth itself.
Eating a diet rich in sugar and starch increases the risk of tooth decay, and sticky foods can be a particular problem because they are more likely to remain on the surface of the teeth.
Frequent snacking also increases the amount of time that acids are in contact with the teeth.
In the absence of good oral hygiene, it doesn't take long for damage to begin. The acids generated by the breakdown of food stuff in the mouth can begin to attack the tooth enamel within 20 minutes of a meal.
It is thought that tooth decay only became a widespread problem with the establishment of sugar plantations in the 18th century, and worsened with the subsequent widespread cultivation of sugar beet in Europe.
The most obvious sign of tooth decay is toothache, particularly after hot or cold foods or drinks. However, pain may not be present until decay has reached an advanced stage.
Pits or holes may also be visible in the teeth.
Most tooth decay is discovered at an early stage during a routine check up.
A serious complication can be the development of a tooth abscess - the build up of pus resulting from a bacterial infection of the centre of the tooth.
Infection may spread out from the root of the tooth and to the bones supporting the tooth.
Plaque and tartar also irritate the gums, and lead to a gum disease called gingivitis which often leads to dental loss even if the tooth itself is healthy.
Treatment and recovery
The best way to keep your teeth in health condition is to ensure that you have a healthy diet without large amounts of sugars and that you clean your teethregularly to get rid of any plaque build up.
Most dentists recommend that you clean your teeth at least twice a day. Using a toothpaste containing fluoride is probably a good idea as this provides the teeth with added protection from the effects of acid.
Flossing between the teeth is also a good idea, as is rinsing out your mouth after eating sticky foods or sugary drinks.
It is also important to have a regular check up at the dentist - most suggest once every six months to a year.
Unfortunately, even good oral hygiene does not prevent decay as the bacteria congregate in areas inaccessible to brushes and floss.
Once the structure of a tooth has been damaged by decay, there is no way to repair it. However, if decay is picked up at an early stage its progression can be blocked. Decayed material can be removed, and replaced with a restorative material such as silver alloy, or plastic. This is known as a filling.
If the decay is more extensive, then another option is a crown. The decayed or weakened area is removed and repaired and a covering jacket - the crown - is fitted over the remainder of the tooth.
If the nerve in a tooth has died, either from decay or a blow, then a dentist will consider root canal work.
This involves removing the centre of the tooth, including the nerve and blood vessel tissue.
The root is then filled with a sealing material, and the process is completed with either filling or possibly a crown.