Fluoride gel for braces

[casuus]

I currently have braces and got told by my dentist to use a fluoride gel for my teeth every week to avoid the brackets staining my teeth and get weird yellow spots once my braces get removed. But I heard that fluoride is bad for your testosterone and can lower your full skull development potential during puberty. Is anyone familiar with the severity of fluoride exposure during puberty and if there are any alternatives I can do to not get weird stains when I remove my braces.