I wouldn't fill your schedule with general education courses in science by any means, but taking a few of them that might be easy, especially when you're otherwise filling up on sciences, could be a GPA booster.
ex. take 3 science classes (actual science classes--upper level BCP's), 1 class you need for your major that isn't hard, and 1 general education science class that isn't hard and interests you (nutrition and food and health courses is a good pathway to go on for dentistry I think, and nutrition counts as "science" though not BCP)
That's a bit of schedule balancing, but it gives you 2 not hard classes that will give you more room to focus on the 3 science classes you're taking, plus the food science class if it's in the nutrition department will count for science GPA. Also I wouldn't recommend taking more than one lab class per semester unless it's a pure lab class. So if you're taking a 4 credit prereq with a lab attached, I wouldn't recommend taking another prereq with a lab attached in the same semester. I guess what it boils down to is don't stack too many labs. You could take a pure lab class like Molecular Bio lab, though. What I mean by pure lab class is a class that is just a lab and just composed of writing lab reports with possibly a presentation or two. That's what I've learned about composing a balanced schedule anyway.
If 3 science classes is too much for you, take 2 and then take another class for your major instead of adding another easy "science." I wouldn't take more than one easy "science" per semester. And maybe not even every semester.