yes gum disease can be horrifying. u can get the CET small brush from the internest; it's really tiny; also my vet recommended to use the baby toothbrush; they have tiny heads and they are cheap
i aslo use the Bluto's Yummy Gum Brush that i apply with a qtip; and biotene maintenance gel that i apply with my finger; besides using the CET toothpaste vanilla/min with the brush. you can get most of these on amazon. good luck
Amazon.com: Bluto's Yummy Gum Brush: Home &...