My dentist advised me to wear braces for the next two years, the not-easily-removable type. My question is whether I can use the Mikvah with the braces? Whether my immersions would be Kosher? (I am 35, with two kids, the little one is not-yet weaned).

Shalom U'verachah, If they can be removed they should be removed before going to the mikvah. If they cannot be removed then you must clean them well and can then go to the mikvah. Kol Tuv