My dogs get their dental care mainly from a (mostly) raw diet.
My small dog (17lbs) gets a variety of raw meaty bones and is probably similar in size to your dog. He gets chicken feet, chicken necks, chicken drumsticks, lamb femurs, pork necks, whole sardines, beef and pork ribs, among other things. Sometimes I feed these bones frozen, sometimes thawed. Some of these are too big to be consumed in one meal, however I give him the whole bone, allow him to chew down/eat an appropriate amount, and then take it from him (always trade, don't just take! Don't want to create resource guarding problems). I do this because it is less of a choking hazard if he eats a large bone in a few sittings versus cutting them into portions, but to each their own. I'm just paranoid.
Feeding raw bones is also great for enrichment and mental stimulation, on top of dental benefits. Chewing is a great way for dogs to destress and compress.
Another thing I've found good for my dog's teeth, his front teeth especially, is the Lickimat. They're on amazon for relatively cheap. I smear this with raw ground meat or sometimes mashed banana, greek yogurt, peanut butter, etc, and then freeze it. My dog chews mostly with his back teeth and doesn't really pick meat off of bones with his front teeth, and this has done a great job at removing tartar from his front teeth.
It should also be mentioned that dental issues can be genetic and are especially common in small breeds. My 9 year old rottie mix has immaculate teeth while my 3 year old small mutt has some tartar issues even though the rottie has only been eating raw for 2-3 years and my small dog has eaten raw his entire life. So it's never a bad idea to also implement regular brushing, on top of raw bones.