Hi I'm also Canadian so maybe I can help you out.
If you do a 5th year and only take courses that you can do well on, you can probably raise your GPA. If you don't, you'll have to rely on your current GPA, which is fine but unless you have strong extracurricular activities, I wouldn't recommend it. And with your current GPA, a signficant portion of your admission will depend on your DAT scores and how early you apply. My brother graduated from UofT a few years ago and got into some good schools with a ~3.4 GPAand 21AA. He said the key was to apply as early as possible for American dental schools and have a good DAT score. It makes all the difference between getting in or not (unlike Canadian schools). Here are some Canadian friendly schools my brother recommended me apply to:
-Detroit
-NYU
-Boston
-Nova
-Upenn
-Columbia
-Umich
Also, I wouldn't recommend applying to Australian schools if you ever plan to practice in the US. I heard their lincences don't work in the US and will be considered "international", so you have to do some extra school to practice in the US. I hope that helps.