Hi,
I also did dental materials a few years back and am now going into my fourth year year of dentistry this september. I personally hated the first year and regretted it so much, but then after that I actually really enjoyed it once I had sort of accepted the fact that I had to do it as a means to an end. I agree with pretty much everything on the pros/cons list above but would also say that the fact that you are doing an engineering degree makes you stand out against other applicants when it comes down to applying. In my year I think the majority of people that applied are now studying dentistry so there is quite a good chance of getting in. Some universities can be a little bit odd about the course, saying there might not be enough biology in it (I know Kings said that to some people, yet me and one other still got interviews), but I dont know if the course has changed since I was on it in terms of content.
If you have any questions, don't hesitate to ask!