In this thesis we have discussed the importance of the health of preschool children's teeth. We were mainly refering to the oral hygiene which is necessary to keep teeth healthy. It is important to care about oral hygiene from the first year of children's life in the same way as we take care of the health of our whole body. Baby teeth will eventually fall out but they set the foundation for permanent teeth which is why we should not neglect them. Parents have the key role in maintaining childs teeth healthy in the first few years of their life. They encourage them to gain habit of regular oral hygiene and also teach them how correct oral hygiene looks like and why it is important. The best way to encourage them is their own example because children learn by the model even the hygiene habits. They teach them about diet, as well, which has a key role in prevention of all kinds of diseases. Correct diet protects teeth of the most common disease which is caries. In this work, we used theories of other authors, who have been exploring this theme, and compared them. By studying these theories, we got to the cognition of the cosequences which may happen if we don't take care about our oral health and got introduced with prevention of all kinds of teeth diseases. Children should be aware of the diseases and it is important to them to hear about it because it is a big encouragement to them. Even from the earliest years they know that it is better safe than sorry. In the end we thought about methods which may encourage kids to visit dentist, who is important in maintaining oral health, and performed project of introducing children with oral hygiene habits.