The aim of the present study is to evaluate the presence of fluoride in saliva after applying professional use products on the surface of dental enamel. The absorption of the fluoride ions from the oral fluids in the sound enamel is low and limited at a neutral pH. If the fluoride ions are present in the mouth at the time when the pH is decreasing and the carious lesion is starting, their effect is to inhibit the demineralization of the enamel by promoting the remineralization. The study was carried out with 20 student’s of10-15 year-old children from School. All of them had good oral and general health, and normal salivary flow. The fluoridated gel was applied in individual trays made after the imprint of the dental arches. The fluoride concentration was measured in the salivary samples collected before the fluoridation and after, at 15 minutes, 1 hour, 2h, 12h. The high fluoride concentration in saliva after the use of Fluoride gel may be important on dental caries prevention in children or adults, especially for individuals with compromised salivary flow or the ones who live in deficient fluoride areas. However, further clinical research is necessary to clarify this issue.