hey,
I applied for Undergraduate entry in the 2007 BDS program. I don't know about the Postgraduate programs, but for the Undergraduate course, yes, there is a 15 minute interview in English (they simply 'ask' you in the interview if you can speak Cantonese).
They basically don't even ask much. There's a panel of 3 professors sitting in front of you, and each one asks one question or so.
First of all, they ask you to "tell us about yourself".
They then go onto asking you (well for the undergraduate program at least) "why do you want to study Dentistry, and what do you like about Hong Kong?"
They also asked me if I was studying another degree, and I told them yes, so they asked me what it was, so if you're wanting to apply for Postgraduate entry, I'd say they might ask something like "what was ur previous degree? why do u want to do dentistry now?" (or something like that)
Then comes very brief questions like
"Do you plan to practice in Hong Kong?"
"Do you have Hong Kong Permanent ID?"
"Do you speak Cantonese?"
I don't know if it's the same for all candidates, but for my interview, they assumed different roles where one professor was nasty and challenging and shaking his head constantly, the second was challenging but not nasty, and the third one was more silent and neutral. I guess maybe they wanted to see how well the candidate functions under pressure.
I took the chance, and flew over to take the interview, because I really want to do Dentistry - if it's really what u want to do, why not go for it. And it's a short interview, so don't spend time looking heaps deep into really hard questions they could ask, because the interview is really short, and they'll prob just ask basic questions like the ones I typed above.
Hope that helps, and best wishes!
wj =)