Problems with fluoride administration - short

Hello, could you please correct the two paragraphs below?

One of the issues we faced was determining the right amount of fluoride concentration for children. To decide this, we did extensive research so as to remain with the upper and lower boundaries in order to avoid the development of fluorosis which occurs when excessive fluoride is ingested during the formation of the teeth.

The other issue we faced was that we needed to find young subjects that actually wanted to refrain from eating fluoride rich foods such as grapes, potatoes, shellfish, spinach, raisins for two months. Only with these restrictions could they become eligible for our baseline examination. This was a challenge because not many children enjoy having dietary restrictions. Since fluoride is present in most foods, the restrictions were necessary.

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I altered this so as to make it sound more like a formal scientific journal. If you were going for a more informal tone, some of the corrections would not be necessary, for example, replacing "kids" with "children".

I updated my facebook.

Recently I updated my Facebook for the first time in 4 years. It brought back memories for me. I was so busy taking care of my kids that I couldn’t check it regularly.

My friends made the same comments to me as that day.

Although I can’t meet them now, I ‘m so happy to connect with them on Facebook.