If a dentist noticed oral leukoplakia would they 100 percent tell you? ive had white film on my tongue for years but go to dentist every 6 months

We hope so: White film on tongue is white film on tongue, not likely to be leukoplakia. You should be able to scrape or brush this off with floss, tongue scraper or brush (stick tongue out, place whatever on tongue near back and then pull tongue back in mouth). Leukoplakia will not wipe/scrape off and looks more like white adherent skin - think what a callous looks like after swimming. See Dentist if needed.

Of course 100%: Leukoplakia generally developed due to irritation from tobacco, rough teeth, fillings, or crowns rub against your tongue. Most patches improve on their own. However, a biopsy is always warranted. See your dentist for evaluation and treatment if needed.