I have a friend who got into griffith Dentistry in 2005 after completing BScience at Sydney uni with a finishing GPA of approx. 4.5. He failed a few subjects in BScience so had to repeat a year (That sucks!) and his UMAT score was very average.
Mind you, he absolutely smashed the interview (but you only get an interview based SOLEY on your umat score) so he must have just scraped in with that umat mark. He had also been a dental assistant for a few years, which would have helped with the interview.