Dental decay is a common phenomenon to day amongst the population in some of the industrialized countries, probably due to the dietary changes which have taken place during the last 5 decades with sugar based products increasingly dominating the portfolio of processed food industry. It is estimated that practically the entire population in a country like the US suffer from some degree of tooth decay while this phenomenon is not that predominant in Europe. Dental decay is caused by bacterial plaques that develop between the teeth because of infection of the gum by microorganisms like Streptococcus mutans and some strains of Lactobacillus which thrive when the diet is rich carbohydrates mainly sugar, causing a drop in pH to about 5. At such an acidic environment the enamel material that coat the teeth are dissolved and lost damaging the tooth progressively. The legendary saying that "brush the teeth after each meal" is based on the effectiveness of removing the "food" for the bacteria left over by the meal promptly giving no cause for plaque formation. Besides almost all brands of tooth paste products contain fluorides that can help remineralization of the affected teeth.
Fluorides are known to inhibit dental decay and water used every day generally contains sufficient fluorides to afford protection to the teeth. But modern day water purification process removes practically all fluorides along with other undesirable inorganic salts to ensure its potability. After all fluoride is not proven to be an essential nutrient and there are no water standards which stipulate minimum or maximum levels permitted or mandatory. Mounting evidence about the role of fluorides in reducing tooth decay has persuaded many countries to take up "fluoridation" of water as a public health measure. Such a practice combined with use of fluoride containing tooth pastes is presumed to have halted the onslaught of dental decay in many parts of the world, benefiting over 400 million population. When water is not a convenient medium for fluoridation, others like salt, sugar, milk etc also can be candidates for mass fluoridation. Fluoride compounds Sodium Fluoride, Fluorosilicic acid and Sodium Fluorosilicate are commonly used as sources of fluoride.
As halogens are increasingly being shunned because of their carcinogenicity, fluoridation also is a suspect process in the eyes of many critics. However there is little evidence implicating this mineral in any serious health disorders. Defluoridation is still recommended when the fluoride content in water is abnormally high, especially in industrial areas, coal belts and deep under ground water. It is more or less agreed now that fluoridation of water @1 mg per liter is absolutely safe and adult human beings can tolerate a level of 0.1 mg per kg body weight. There are some organized groups still agitating for stopping compulsory water fluoridation, raising ethical and societal issues. However, if iodization of salt is accepted as a public health program to prevent mental retardation and development of goiter, there should not be any reservation about the fluoridation program too.
Fluoride absorbed by the body is circulated in the blood and when adequate fluoride intake is ensured, the saliva contains about 0.04 mg per ml of this chemical that can prevent dental decay. Under such a situation the fluoride in saliva reacts with the bacterial plaques dissolving the enamel substances and subsequently the affected teeth gets recoated with a thin layer of this solution as a part of the process of demineralization. Decay becomes a serious problem when demineralization rate exceeds remineralization pace over a period of few years. There are suggestions that Calcium present in water and Xylitol chewing gum can also retard dental decay but they can at best be complimentary to fluoridated water.
Traditional Indian practices of using neem sticks, mango leaves, charcoal powder mixed with camphor etc are known to maintain dental and gum health but very scant scientific supporting evidence is available regarding their mode of action. Most probably neem and mango may be acting as antibacterial while charcoal powder has the capacity to adsorb gases and very small particulate materials including bacteria, thus preventing the very process of plaque formation. Regular gargling with warm water after each meal has the salutary effect of flushing out residual food particles struck between the teeth and also forced removal of adhering bacteria without giving them any chance for colonization. Use of dental floss by many people serves the limited purpose of removing food particles which provide the source of food for the infectious bacteria.