An extraction can also serve as treatment for dental caries. The removal of the decayed tooth is performed if the tooth is too far destroyed from the decay process to effectively restore the tooth. Extractions are sometimes considered if the tooth lacks an opposing tooth or will probably cause further problems in the future, as may be the case for wisdom teeth. Extractions may also be preferred by people unable or unwilling to undergo the expense or difficulties in restoring the tooth. Epidemiology
Worldwide, approximately 3.6 billion people have dental caries in their permanent teeth. In baby teeth it affects about 620 million people or 9% of the population. The disease is most common in Latin American countries, countries in the Middle East, and South Asia, and least prevalent in China. In the United States, dental caries is the most common chronic childhood disease, being at least five times more common than asthma. It is the primary pathological cause of tooth loss in children. Between 29% and 59% of adults over the age of 50 experience caries.Treating dental cavities costs 5–10% of health-care budgets in industrialized countries, and can easily exceed budgets in lower-income countries.The number of cases has decreased in some developed countries, and this decline is usually attributed to increasingly better oral hygiene practices and preventive measures such as fluoride treatment. Nonetheless, countries that have experienced an overall decrease in cases of tooth decay continue to have a disparity in the distribution of the disease.
Some neurotransmitters may make the receiving cell more sensitive, while others tend to make the receiving cell less sensitive. Laboratory studies suggest that an imbalance between these chemicals may underlie myoclonus. Some researchers speculate that abnormalities or deficiencies in the receptors for certain neurotransmitters may contribute to some forms of myoclonus. Receptors that appear to be related to myoclonus include those for two important inhibitory neurotransmitters: serotonin, which constricts blood vessels and brings on sleep, and gamma-aminobutyric acid (GABA), which helps the brain maintain muscle control. Other receptors with links to myoclonus include those for benzodiazepines, drugs that induce sleep, and for glycine, an inhibitory neurotransmitter that is important for the control of motor and sensory functions in the spinal cord. More research is needed to determine how these receptor abnormalities cause or contribute to myoclonus. Treatment
Concerning more serious conditions, the complex origins of myoclonus may be treated with multiple drugs, which have a limited effect individually, but greater when combined with others that act on different brain pathways or mechanisms. Treatment is most effective when the underlying cause is known, and can be treated as such. Some drugs being studied in different combinations include clonazepam, sodium valproate, piracetam, and primidone. Hormonal therapy may improve responses to antimyoclonic drugs in some people. Some studies have shown that doses of 5-hydroxytryptophan (5-HTP) leads to improvement in patients with some types of action myoclonus and PME. These differences in the effect of 5-HTP on patients with myoclonus have not yet been explained.