The goal of this clinical trial is to learn if Chitosan mouthwash works to affect the recurrence of black stains in pediatric patients. The main questions it aims to answer are:

Does Chitosan mouthwash lower the number of times participants need to do a scaling and polishing cleaning sessions more than normal? Does Chitosan mouthwash will decrease the recurrence of black stains in children and improve esthetics ?

Participants will:

Take chitosan every day for 4 months Visit the clinic once every 6 weeks for checkups and data collection

Inclusion Criteria:

• 1. Cooperative child to be able to perform and tolerate different oral hygiene procedures 2. Parents providing informed consent 3. Accept 18 weeks follow up period 4. Teeth showing black stains without calculus.

Exclusion Criteria:

• 1. Patients with Allergic reactions to food & drugs containing derivatives from crustacean organisms. 2. Taking any antibiotic drugs within 2- week period before sample collection. 3. Taking any dietary supplements containing iron. 4. Teeth selected should be free of caries 5. Free of any developmental defects