Also, I get sent a voucher once a year for each of my kids for a dental check up. From Centrelink or the Government or someone (don't look a gifthorse and all that!) - they also get low cost dentistry through the school dentist service - about $30 a time i think it is, as long as they're in full time school, so between those two I manage to get my kids' teeth checked twice a year for minimal cost. Luckily so far neither have needed anything orthodontally. Again though, I think even with private cover, you're limited as to how much of orthodontic costs you can claim back in a year.
For us adults, I just pay direct - found it works out cheaper that way than the regular private cover costs. I always make sure I tell the dentist first that I am doing this, so he doesn't do extra bits without checking first!! You can also claim something like 20% back against tax for any medical costs over something like $1500 a year - that includes other medical stuff (like my laser eye surgery last year) and also dentists stuff I understand. Check with your friendly accountant!!