Brushing your dog's teeth

My partner and I recently brought our yorkie to the vet to get her yearly shots. The vet took one look at her teeth and told us that they were starting to rot. So we haven't brushed her teeth for 4 years as well and just recently we started. I hold her head firmly and she's getting used to it, but by no means does she like it. Already I've seen black plaque on her teeth disappear. We also bought her food that cleans her teeth and she eats it right up.