Assuming you’re not doing the post-bacc to help boost your grades, just get your requirements done. I wouldn’t waste money on classes that aren’t required to apply. If you can handle doing everything you need in 1 year, I’d go for that. It also doesn’t need to be a formal post-bac program. Mine was a mix of non-matriculant coursework at my alma mater and online coursework elsewhere. Depending on where you want to apply for dental school, they may or may not accept online coursework though.
Disclaimer: I have no experience in admissions. I did take a post-bacc.