Fluorides have the ability to get incorporated into the tooth structure and make the teeth more resistant to dental decay. The use of fluorides may even arrest progression of caries which are in the initial stages. Fluoride when consumed during formation of teeth gets incorporated in the tooth structure and makes the enamel stronger. It also has an anti -bacterial effect on several germs that cause decay and makes dental plaque difficult to attach to the tooth.

Children between the ages of six months and 16 years may require fluoride supplements. The pediatric dentist considers many different factors before recommending a fluoride supplement. Your child's age, risk of developing dental decay and the different liquids your child drinks are important considerations. Bottled, filtered and well waters vary in their fluoride amount, so a water analysis may be necessary to ensure your child is receiving the proper amount.

Your child should use toothpaste with fluoride. Young children, especially pre-school aged children, should not swallow any toothpaste. Careful supervision and only a small amount on the brush are recommended. If not monitored, children may easily swallow over four times the recommended daily amount of fluoride in toothpaste.

Fluoride is documented to be safe and highly effective. Research indicates water Fluoridetion, the most cost effective method, has decreased the decay rate by over 50 percent. Only small amounts of fluoride are necessary for the maximum benefit. Proper toothpaste amount must be supervised, and other forms of fluoride supplementations must be carefully monitored in order to prevent a potential overdose and unsightly spots on the developing permanent teeth. Do not leave toothpaste tubes where young children can reach them. The flavors that help encourage them to brush may also encourage them to eat toothpaste.

Topical fluoride comes in a number of different forms. Gels and foams are placed in fluoride trays and applied at the dental office after your child's teeth have been thoroughly cleaned. Fluoride varnish is one of the newer forms of topical fluoride applied at the dentist office. It has been documented to be safe and effective to fight dental decay through a long history of use in Europe.
The advantages of varnish are:

Children who benefit the most from fluoride are those at highest risk for dental decay. Riskfactors include a history of decay, high sucrose carbohydrate diet, orthodontic appliances andcertain medical conditions such as dry mouth

One  may face the condition called enamel fluorosis if he or she gets too much fluoride during the years of tooth development. Too much fluoride can cause in defects in tooth enamel. This condition may also affect permanent teeth. Enamel the outer covering of the teeth appear chalky white. The enamel may become pitted, rough, and hard to clean. In sever case teeth may get brown spots. These teeth may fracture easily.

First and foremost resone to cause enamel fluorosis is drinking water. There are some endemic zone where we find excessive amount of fluoride in drinking water. If that water is consumed during developmental years by a child, he or she may get the condition.
Secondly if a child consumes excessive amount of fluoride supplements or apart from brushing child eats fluoride containing tooth paste during developmental years he or she may get this condition.

Civic authority should monitor fluoride content of water supply. If it is in the endemic zone then people should be educated not to use that water as a drinking purpose. If we fall in those endemic zone then one should have a water treatment plant that can remove minerals from water( reverse osmosis water treatment plant).  
Watch your child's use of fluoridated toothpaste as the second step. A very small amount of paste on the brush is enough for fluoride protection. Teach your child to spit out the toothpaste, not swallow it, after brushing.

Once fluoride is part of the tooth enamel, it can't be taken out. But the appearance of teeth affected by fluorosis can be greatly be improved by a variety of treatments in esthetic dentistry.