Dental caries is a common oral disease. The process of caries formation is a cycle of remineralization and demineralization with various stages being either reversible or irreversible.

White spot lesions (WSLs) are defined as enamel surface and subsurface demineralization, without cavitation. These manifestations represent the first clinical observation of the progression of dental caries, with the possibility of being reversed.

WSLs are characterized by a white, chalky, opaque appearance and are commonly located in pits, fissures, and smooth surfaces of teeth. However, after the placement of fixed orthodontic appliances, there are an increasing number of plaque retention sites due to the presence of brackets, bands, wires and other applications, which make oral hygiene more difficult, and limit naturally occurring self-cleansing mechanisms. As a consequence, there is an increased risk of demineralization and, conclusively, of WSLs forming on smooth surfaces, if there is no effective plaque removal

The clinical characteristics of these lesions include loss of normal translucency of the enamel because of altered light properties with a chalky white appearance, particularly when dehydrated; a fragile surface layer susceptible to damage from probing, particularly in pits and fissures; increased porosity, particularly of the subsurface, with increased potential for uptake of stains; reduced density of the subsurface, which may be detectable radiographically, with transillumination or with modern laser detecting devices; and potential for remineralization, with an increased resistance to further acid challenge particularly with the use of enhanced remineralization treatments.

It is possible to find numerous therapies for WSLs, for instance, hygiene education, fluorides, phosphopeptide compounds, xylitol and infiltrative resins, microabrasion and/or bleaching, and preparation and restoration. The professional application or prescription of fluorides for home use includes: gels, toothpastes, mouthwashes and varnishes. The fluoride ions are revealed in three ways: sodium monofluorophosphate, sodium fluoride and amine fluoride. It has been found that high fluoride concentrations promote WSL remineralization However; it occurs in the enamel surface and inhibits the ions' movement through the subsurface, affecting the subsurface remineralization and therefore, the light reflection

Inclusion Criteria:

• The patients have at least 3 WSLS.
• The patients aged between 16 and 25 years old
• The patients with good general health and no systemic disease.

Exclusion Criteria:

• Presence of enamel hypoplasia or dental fluorosis.
• Presence of carious cavity.
• Allergy to fluoride gel being used in this stufy
• Patients who have a significant medical history, including pregnancy and breast feeding and smokers.
• Patients who have evidence of reduced salivary flow or significant tooth wear.
• Patients who had participating in concurrent clinical trials or who had recently participated in other clinical trials of an investigational drug or device.