That's a tough question to answer, because there is a always risk that your DAT scores can drop if you rewrite it, depending on the sample of the questions chosen for that writing, the candidate pool, (and your corresponding knowledge). I think I heard someone say that the highest cDAT bio score in one of the more recent sittings was a 20? (not 100% sure about this though!) Ultimately, I think it really comes down to whether you have a strong preference over schools in the US or Canada.
Personally, the financial cost of tuition in the States was a very significant drawback for me. My consensus from speaking with practicing dentists/specialists are that current choices for dental school will significantly restrict the financial viability of specialization in the future. Particularly if you want to do specialty training in Canada, majority of the programs will require you to pay tuition (apart from OMFS I believe). Even though the cost of specialization training may not seem insignificant, the net delta of what you're paying vs what you can be making as a GP to pay off student loans during the same time period is actually significant - especially when coupled with interest rates. Of course, if you're quite sure that you are able to take on the financial aspect of pursuing dental school in the states (and that doing so wouldn't restrict your choice whether to specialize or not), then NOT re-taking the DAT and applying with your current stats is the safer option. Even though its on the lower end, the candidacy pool for Canadian schools does fluctuate every cycle and you never know!
On the other hand, if you're heavily favouring Canadian schools over American ones, then the risk of re-taking the DAT may be worthwhile. That is, studying extremely hard and going for a higher DAT score - or pursuing more coursework/Masters to boost your GPA in order to increase your chances at a Canadian school. In the end, it really comes down to knowing yourself, your own financial situation, and being wise about financial choices associated with each option. After all, dental (or any professional education) is like an investment (of time, money, and more). The investor can get input from other people, but ultimately they're the only ones who can decide whether or not the investment is worthwhile pursuing! I interviewed at dental schools in both the US and Canada & I know the process can be really daunting. This is my take on your situation, but feel free to PM me if you have additional questions!