Cleaning your dog's gums and gum line is just as important if not more important than getting those teeth cleaned. Though you may not want to stick a toothbrush in your dog’s mouth, you also don't want your dog to have periodontal disease. Dental disease in your dog is not much different than periodontal disease in humans. It causes red and puffy painful gums that eventually recede causing tooth and bone loss. Getting your dog's gums nice and clean will keep his mouth healthy, which in turn, improves his overall health. If your dog is nervous at all about brushing his gums, separate that task from brushing his teeth.
It does take some time for dogs to get used to dental cleaning at home or with a veterinarian. Your dog may not enjoy having a toothbrush in his mouth or tasting something like baking soda or dog toothpaste. Try to keep tooth and gum brushing short and simple but often enough to make a difference.