For patients with a high caries rate or high-risk assessment for caries (undergoing orthodontic therapy), concentrated topical fluorides may be prescribed for home use. Topical concentrated agents for home use include 0.5% acidulated phosphate fluoride, 1.1% sodium fluoride gel and 0.4% stannous fluoride gel. Stannous fluoride gels are preferable for younger children because a 0.4% stannous fluoride preparation is approximately one-fourth as concentrated as 0.5% acidulated phosphate fluoride. The gel is available without a prescription. The patient is instructed to brush a small amount of gel on the child’s teeth before bedtime. Expectoration is encouraged however no eating or drinking for 30 minutes. Depending on the formulation and concentration of the product, application is daily or weekly.