The goal of this clinical trial is to compare the treatment effect of vitamin D supplementation and topical fluorides in the population having vitamin D deficiency and Initial Carious Lesions (ICL) on the progression of ICL in teeth. This study aims to observe the changes in the International Caries Detection and Assessment System (ICDAS) scores, the concentration of salivary proteins, and cariogenic microbes, six months after the interventions.

• Group A will get vitamin D supplements and oral hygiene instructions (OHI).
• Group B will get vitamin D supplements, topical fluorides, and OHI.
• Group C (Control), the vitamin D sufficient group will get topical fluorides and OHI.

The study investigator will conduct a multi-centered randomized clinical trial in the outpatient department of Operative Dentistry, in three units of Dow University of Health Sciences (DUHS), with parallel treatment assignment to an experimental, active comparator, and control groups. The investigator will recruit study participants aged 12 to 45 at moderate risk of dental caries, specifically those with vitamin D deficiency. Additionally, participants must have at least two clinically diagnosed teeth with initial carious lesions (ICL). Each participant will be enrolled for six months in this trial.

The investigator will obtain data on vitamin D deficiency from Dow Diagnostic Laboratory. Dental caries risk will be assessed using a caries risk assessment (CRA) form, while ICL will be evaluated through the International Caries Detection and Assessment System (ICDAS) scores. The investigator will collect the samples of participants' saliva to analyze salivary proteins using the enzyme-linked immunosorbent assay (ELISA), and cariogenic microbes through polymerase chain reaction (PCR).

Participants will be assigned to one of three groups randomly:

• Group A participants will be vitamin D deficient with caries, receiving vitamin D supplements and Oral hygiene instructions (OHI).
• Group B participants will be vitamin D deficient with caries, receiving vitamin D supplements, topical fluorides, and OHI.
• Group C participants will be vitamin D sufficient to be considered as controls for comparison, receiving fluoride application and OHI.

The investigator will assess study outcomes by observing changes in ICDAS scores, salivary protein concentrations, and count of cariogenic bacterial species (Streptococcal mutans and Lactobacilli).

Inclusion Criteria:

• Patients of all genders and ages ranging from 12-50 years, having at least two teeth with clinically diagnosed Initial Carious Lesions at Moderate Risk of Dental Caries, after written informed consent.
• Patients having vitamin D deficiency.

Exclusion Criteria:

• Patients who have heavy calculus, gingivitis, or periodontitis.
• Patients using desensitizing toothpaste or mouthwash up to six weeks before the study.
• Patients who have severe intestine or kidney disease, malabsorption syndrome, or any other conditions affecting vitamin D metabolism.
• Patients on antibiotics or probiotics therapy for the last month
• Pregnant females.
• Patients with poor oral hygiene and with excessive dietary exposure to acids and carbohydrates.