The aim of the study is to evaluate the efficacy of intensive and biannual application of  Duraflor Halo fluoride varnish in reducing  caries incidence among school children 6 to 8 years. groups so that each group contained 150 children. The

Groups will be formed so that each group will contain 25 children.
The groups will be as follows:
Group 1 (control): Children for whom fluoride varnish will not have been applied.
Group 2 (varnish): Children for whom fluoride varnish will have been applied.

At the baseline examination, children from both groups will have received oral prophylaxis followed by appropriate oral hygiene instructions. Children from the varnish group will have been subjected to intensive application of sodium fluoride varnish (Duraflor Halo Varnish) three times during one week (once every two days). After oral prophylaxis, the teeth will have been dried with an air syringe, and fluoride varnish will have been applied on all teeth using a disposable brush, taking care not to apply it to the soft tissue. The varnish will then be allowed to set for 10 seconds according to the manufacturer’s instructions.

Children who will have received fluoride varnish applications will have been asked to abstain from brushing or flossing for the entire day and will have been instructed to avoid chewing on hard foods, consuming hot drinks, or using products containing alcohol. Children from the control group will not have received varnish applications.

All the children in the control and varnish groups will have been examined clinically at the beginning and at the end of the experimental year. Each child will have been subjected to an ADA Type III oral examination using a mouth mirror and probe. Caries status in primary teeth [DEFT (decayed, extracted, filled teeth) and DEFS (decayed, extracted, filled surfaces)] will have been recorded according to WHO criteria.

Since there will have been a possibility of physiologic exfoliation of primary anterior teeth due to the age group included in the study, to control the bias caused by exfoliated carious incisors, caries status of posterior teeth will have been recorded separately. Caries status for primary posterior teeth (canines, first and second primary molars) will have been recorded as DEFTP (decayed, extracted, filled posterior teeth) and DEFSP (decayed, extracted, filled posterior surfaces) according to WHO criteria. Caries status in permanent teeth [DMFT (decayed, missing, filled teeth) and DMFS (decayed, missing, filled surfaces)] will have been recorded according to WHO criteria.

Two bitewing radiographs will have been obtained for each child at the beginning and at the end of the study. A No. 2 X-ray film will have been placed in the mouth with the help of an intraoral bitewing X-ray film holder to record interproximal surfaces of posterior teeth. A magnifier will have been used to aid in diagnosing incipient proximal lesions from the obtained bitewing radiographs. Radiographically identified proximal carious lesions will have been recorded as RDT (radiographic decayed primary teeth), RDS (radiographic decayed primary surfaces), RDT (radiographic decayed posterior permanent teeth), and RDS (radiographic decayed posterior permanent surfaces).

Using the data recorded on caries at the beginning and at the end of the experimental year, increments in caries will have been calculated.

Oral hygiene status of each child will have been recorded before oral prophylaxis at the beginning and during the one-year follow-up visits as the OHI-S (Oral Hygiene Index-Simplified) index according to WHO criteria. This will have been done to control the bias exerted by oral hygiene status on caries increment.

All the children included in the study will have been examined, and their data will have been recorded respectively by the same examiner.