It is absolutely imperative you wear business casual during ISAC, with the exception of scrubs during anatomy lab. This is the prime time when ALL faculty is watching.
For females, dress pants or pencil skirts for the bottom, and blouses or dress shirts for the top. Flats are the most comfortable to walk around in. For rainy days, you are allowed to wear boots. H&M is your best bet for affordable business casual clothes.
For the pre-dentals, start expanding your wardrobe now because once you're in dental school, it'll be professional attire, not business casual.