Hi Runner,
Here is a link showing root caries (decay). If you are STILL getting a lot of decay discuss with your dentist the option of having fluoride trays made so you can give yourself fluoride treatments at home on a regular basis. If you continue to use the ACT be sure you are using it as directed, swishing for no less than one minute either once or twice a day (depending on the type) AFTER brushing AND flossing. Try to avoid the cinnamon flavouring as it causes the mouth to dry.
Here is the link:Root Caries