dog-specific bones
Merrick pet foods, which we feed our babies, carries a whole line of bones that are very meaty and hold up to even the most rigorous chewing. Don't leave them completely unattended while they're chewing any bone, though...you just never know. We usually buy a couple every time we restock on dog food, so they probably go through two a month, maybe? Last time I took our girl to the vet the doctor just raved about the state of her teeth and I'm sure that's the reason, because we don't brush or do anything else. I can't recommend Merrick products strongly enough (though, quite spendy...but I'll never have to pay to put these two through college!!)