This is actually a really good question and something i dont think i have written so much about... mainly because i dont have so much to say about it. I have been quite lucky with my teeth... when i was younger i pretty much never brushed my teeth, i sucked my thumb for several years so my top teeth were pushed out, but once i stopped sucking my thumb they went back to normal. For several years i purged several times a day for long periods. I spent months drinking 2-4l diet soda per day, i have eaten alot of sweet stuff and still do.... and during my recovery and time at Mando i had to drink about 1-1,5l juice per day...so my teeth? Well im surprised that they look the way they do. They are eroded and not as nice as they could be considering i drink coffee, diet soda (at times) as well as eating lots of chocolate. But i have never had a hole in my teeth, luckily. (Also to mention that my CF care/medicine erodes my teeth -_-')
First off, purging is one of the worst things for your teeth. All the acidity erodes them and can lead to holes, sensitivity and lots of pain. If you purge then your dentist can be one of the first people to find out about it, that was one of the reasons i didnt go to the dentist for a very long time as i didnt want them to find out about my purging. But then also if you dont eat alot i know that can mess up your teeth its like bacteria and acidity forms as well as having very bad breath. (This is something you can google if you want to know more as i dont know loads about this, its just that i have heard it from a doctor in a documentary). But then things like diet soda, lots of acidic juice, coffee, sugar can all mess up your teeth. In recovery it is recommended to drink juice and milk as well as eating more sweet stuff - this is to help you overcome your fear foods. To overcome your fear of sugar, carbs, fat, processed food etc and like i have written in a previous post when you are in recovery it is NOT the same as being recovered. The same rules dont apply. However your dentist might say otherwise. My dentist didnt like the fact that i had to drink so much juice and eat ice cream and pasteries and such when i was in recovery... But she gave me a tip to always rinse my mouth with water afterwards. So that can be a tip for you all if you drink soda/coffee/juice or sweet things.
But over brushing your teeth isnt good either... just like if you eat/drink acidic things or you just purged then DONT brush your teeth, that will make it even worse. Instead wait a while before brushing your teeth.
I would suggest that you eat what is on your meal plan/you keep eating sweet foods, you dont need to eat them everyday, not even in recovery. However you might eat sweet things more frequently than if you werent in recovery ,but this is just a phase in your life and when you are a normal weight or when foods arent fear foods then you dont need to eat them as often, just as much as your body craves it. Whether that is once a week or once a month. But you want to overcome the fear of all foods and have a healthy relationship with food, even if your dentist might tell you that you should never eat candy or sweets. Everything in moderation. Just make sure to try to keep your teeth as healthy and clean as possible for your own sake as well as your dentist sake, haha!! :)
Below are some more links if you want to read about the damage that eating disorders can have on your teeth:
Effects on your teeth
Eating disorder and effect on your teeth