Dentalife promotes chewing in those hard-to-reach places thanks to its unique combination texture, shape and dimension. It will massage the gums and help to reduce tartar build up.
That said, if your dog has a large buildup of tartar already, you may need to have their teeth cleaned first. Your vet will be able to offer the best advice and course of action here.
Just like humans, brushing is still the best way to keep the mouth healthy, although this can be easier said than done with some dogs. Always use a toothpaste that is formulated for dogs (human toothpaste is a no-go!)
For more helpful information on brushing your dog's teeth, take a look at this article.