I picked up a pack of 10 (count them 10) interstitial toothbrushes at the 99¢ store. One of the best dollars I ever spent. Brand name: "Aim interdental brush". They work just about as well as flossing (I still keep some floss stick around for the occasional piece of stuff that gets stuck that these don't get out). Their business end looks like a tiny artificial Christmas tree, with a small plastic handle.