Fluoride is effective in preventing cavities and tooth decay and in preventing plaque from building up and hardening on the tooth’s surface. A fluoride treatment in a dentist’s office takes just a few minutes. After the treatment, your child may be asked not to rinse, eat, or drink for at least 30 minutes in order to allow the teeth to absorb the fluoride. Depending on your child’s oral health or the doctor’s recommendation, a fluoride treatment may be required every three, six, or 12 months.