“pre-dental” is not really a course, anymore than “pre-medical” is. You apply to undergraduate to study any course, and take the required subjects (usually two semesters each of bio, chem, organic chem, physics and English). Often, students who are headed towards a health career will major in a biological science, but it is not necessary.
You do NOT need to start with an American HS diploma, You don’t even have to have an American undergraduate degree, though it can help your odds of being accepted to a US Dental School.
What is usually the issue for international students is $$.
Instead of relying on word of mouth, work on your search skills. Run “international students US Dental School” and the 1st thing my search engine pops up is a posting by the American Dental Education Association (.org) which clarifies all of the above.