Neither of my kids had seen a dentist before the mandatory Kindergarten exam at 5. We didn't brush until ~2, and not regularly until 3 or 4. We don't go to yearly exams (school provides), and don't do cleanings. Kids still don't brush in the AM, but I'm trying to work that into the routine now. At 10, my daughter was one of only a couple of kids in her class that had no cavities. Son is still small. Neither kids flosses yet, which I actually find important and we'll be working on it shortly.
The trick is to a) avoid sugar, and b) space out the meals. This means no sipping on juice/milk/anything all day long, no beverages other than milk or water (no juice ever), no snacks all day long, no sweets ever until 2, and only on weekends after that (and only one or two a day). The pH in the mouth shifts to tooth-decaying after a meal, and then shifts back to tooth-remineralizing after about 20 minutes. if you snack or sip every 20 minutes, your teeth are toast. If you space food out, you'll be fine. This way of eating/drinking is also healthier.