the US. system is weird, you have to complete a pre-med program and then apply for medicine .. it's considered a postgraduate degree .. dunno about dentistry but i guess its the same 
UK system is the best .. 5 years and ur done! 
and i dunno about Australia .. but i guess theyre the same as the UK .. but check their web sites or something 
I'm also planning to go into medicine InshaAllah.
In the country i live in only one medicine uni it's well known but it's fees are

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Yes it's true if you want to apply to the uni in the country i live in
to medicine program you have to apply to pre-med program first which is 2 years,
then 4 years of medicine.
If you say that uk system is 5 years that's good

I heard that some uni's in egypt accept 8 Ig's and they're Uk system with a reasonable fees,