One hundred children with white spot lesions on their teeth were divivided into 5 groups of different remineralizing agents to assess their effect on color change and remineralization

Children having at least one tooth clinically diagnosed by white spot lesion were randomly allocated to five groups.

Group one: No treatment was applied (negative control). Group two: Fluoride gel was applied for 5 minutes (positive control). Group three: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (MI paste) was applied for 5 minutes.

Group four: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) + fluoride (MI paste plus) were applied for 5 minutes.

Group five: Nano hydroxyapatite paste (Apagard primo toothpaste) was be applied for 5 minutes.

All children involved in this study were instructed to brush their teeth under the supervision of the researcher before the application of the studied agent.

Each agent was applied to the labial surfaces of each tooth affected with white spot lesion for 5 minutes after cleaning and drying with a cotton roll using an applicator tip. After each application, children were instructed not to eat or drink for one hour. This application was be repeated in-office after one then after two weeks then after six weeks.

Participants received a sterilized pouch containing a sterile container with one of the pastes according to the study group for home application. The application of the paste was carried out under parental supervision and was asked to apply each of the pastes at home three times a day till the end of the study

Inclusion Criteria:

1. Presence of at least one tooth affected by white spot lesion.
2. Good oral hygiene and regular tooth brushing at least twice daily.

Exclusion Criteria:

1. Unwillingness to be randomly assigned to 1 of the 3 treatment groups.
2. Presence of abnormal oral, medical, or mental condition.
3. Presence of any milk-related allergies.
4. Presence of dentin caries or enamel hypoplasia on maxillary anterior teeth.
5. Presence of periodontal pockets around maxillary anterior teeth.

Blinding to the child participants and legal guardian of each participating child, inter examiner and statistician. The operator and the child were blinded to the intervention from the beginning till teeth polishing. Blinding cannot be done during application of remineralizing agents because of clear visual differences between these agents.