Inclusion Criteria:  1- An age range of 10-24 years ( age of young adolescents and youth as described by the WHO was selected (WHO, 2019). 2. The presence of at least one visible WSL in the buccal surface of permanent teeth with ICDAS II score of 1, or 2. 3. Completion of an informed consent to participate in the study  Exclusion Criteria:  1. Patients receiving the following medications: tetracyclines, any other medication known to stain teeth or any medication causing dry mouth and/or limiting salivary flow. 2. Patients receiving any antibiotic within 1 month prior to each saliva sample collection 3. Selected tooth with microcavities or dentinal involvement due to loss of enamel tissues. 4. Selected tooth with a restoration adjacent to the lesions to avoid false- positive readings. 5. Selected tooth with fluoride application &lt; 3 months prior to study treatment. 6. Selected tooth with discolouration, enamel hypoplasia or fluorosis. 7. Patients with multiple cavitations to avoid variability in microbiological analysis.