I just went through a very similar thing - I will tell you what I learned. It might help:
- We use bottled (unflouridated) water for drinking, but tap (flouridated) water for cooking. My pediatrician told us that would be enough for the kids not to need flouride drops (I sort of disagree - see below).
- The danger with too much flouride is that the permanent teeth will have indelible orange and/or black spots.
- My five-year old had seven cavities when we took him to the dentist. It cost about $1000 and three trips to fix them. The dentist said there were three factors that led to the cavities:
1) Not enough flouride. He didn't knock the bottled water, but suggested a rinse, like ACT, etc.
2) Not enough flossing. We hadn't been flossing at all. The cavities were on the sides of the molars where the walls of the teeth touched and food got trapped. We started using the reach floss wand, which is easier for my kids to use than plain floss.
3) Lots of small snacks throughout the day. He said the defenses of your teeth wax and wane throughout the day, so there are times in the day (especially bedtime) when they're more vulnerable than others. He said he knows snacking throughout the day is healthier, but it's harder on the teeth. He recommended having the kids drink or swish a little water at the end of a meal (to be honest, we still don't do this).
And finally:
- There are two kinds of flouride. The kind you eat or drink (like in your water) and the kind the dentist puts on your teeth, or you get from a swish-and-spit rinse. The kind you eat/drink only helps while teeth are being formed (i.e., right now for your kids), the other kind temporarily bolsters your teeth (which is why they have to do it repeatedly).
One piece of hearsay was that after a certain amount of time, your teeth get "used to" the flouride in swish-and-spit rinses and they aren't effective anymore. But no dentist has ever said that.