This article focuses on what causes the most common oral cavity diseases (dental caries and periodontitis). Since their main etiological factor is bacterial plaque, the basic preventivě pillar for these diseases, as well as periodontitis treatment is the correct and efficient Ímplementation of personál oral hygieně. This consists of both mechanical and chemical plaque removal twice a day using oral hygieně devices and professional cleaning during routine dental check-ups. An integrál part of prevention is to use the cariostatic and bacteriostatic effect of fluoride in toothpastes or applied as part of a fluoride programme. One other important preventive measure is dietary advice to cut down on food and liquids containing fermentable carbohydrates.

        Key words: prevention, oral microbiota, plaque, dental caries, periodontitis, oral hygiene