Can plain, unsweetened soy milk cause tooth decay for my toddler?

Tooth Decay: Too much emphasis is placed on sugar being the cause of tooth decay. All sources of carbohydrates cause tooth decay! the stickiness and concentration of sugars determines how cariogenic the food may be. The true cause of decay specially in toddlers is the lack of daily dental home care by parents. It is not like a stinky dipper screaming to be change. You as parent must make it a priority.

Yes: Almost any food when not brushed away will feed cavity-causing bacteria in the mouth. Even things that aren't "sweet". Some of the only exceptions are fodds which are sugar and starch-free such as nuts, broccoli, lettuce, etc. Brushing and good oral-hygiene is critical for toddlers (and adults!).

Yes: It is less likely to cause decay than fruit juices but it can still cause tooth decay.