It depends what university you want to go to. In NSW there is only 1 undergraduate dentistry course, at CSU orange. Entry is based on ATAR or university results and interviews, so you can enter straight from high school. University of Sydney also has a dentistry course however it is graduate entry, so you must already have a bachelors degree and entry is based on results from your undergrad degree, the GAMSAT (like the UMAT but for graduate entry), and interviews. USYD does have a bachelor of oral health also which is an undergrad degree, and entry is based on a combination of ATAR, a PQA exam and interview. This course is what I am currently doing and it is part of the faculty of dentistry, but qualifies you as a dental hygienist or dental therapist, not a dentist.
There are a few undergrad and graduate entry degrees available at other universities around the country but I am not confident on the exact details of these so I advise you check out the UAC guide or just search around online.