Q. Iodine + F varnish protocol:
1. dispense 4-5 drops of povidone iodine (betadine) in a container, e.g. dappen dish.
2. dry as you would for F varnish, doesn't need to be perfect.
3. soak iodine with cotton swab (Qtip), wipe onto teeth, focusing on high risk surfaces. For posterior interproximal areas, push the Qtip a bit at the embrasure, and the iodine will flow in.
4. place F varnish immediately without any rinse or wiping.
Q. Does it stain teeth and/or composite restorations?
No. Iodine is brown, but does not stain whatsoever. It looks like it stains on cloth, but can be rinsed easily.
Q. What type of iodine do you use and how much per application?
Any drug store will have a generic ~16 oz. bottle of povidone iodine ($~16) and a brand name Betadine (~$20). They are the same. 16 oz is enough for ~400 treatments using 4-5 drops per patient. Do not buy the fancy dental foam products, they taste terrible, get everywhere, and there is no evidence that they work.
Q. How about taste?
If it is just applied to the teeth the taste is pretty subtle. If you rinsed with an entire oz, it would be very metallic. I have had a couple Asian kids complain about the flavor. Otherwise kids object to the F varnish not so much the iodine.